UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D. C. 20460 May 22, 2006 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES MEMORANDUM SUBJECT: Benefits and Cost Analysis of PCNB and Alternatives for Use on Golf Course Turf ( Tees, Greens, Fairways), Cotton, Potatoes, Green Beans, and Cole Crops ( Cabbage, Brussels Sprouts, Cauliflower) ( DP# 328903, DP# 328904)

FROM: Leonard Yourman, Plant Pathologist Biological Analysis Branch Tara Chandgoyal, Plant Pathologist Biological Analysis Branch David Donaldson, Economist Economic Analysis Branch THRU: Arnet Jones, Chief Biological Analysis Branch Biological and Economic Analysis Division ( 7503P)

Tim Kiely, Acting Chief Economic Analysis Branch Biological and Economic Analysis Division ( 7503P)

TO: Jill Bloom, Chemical Review Manager Special Review and Reregistration Division ( 7508P)

Product Review Panel Date: May 3, 2006 SUMMARY The Agency has identified PCNB ( quintozene) and its metabolites as being persistent and bioaccumulative in the environment. In addition, there is evidence of long range transport through the air due to PCNB volatility. The Agency is interested in identifying alternatives to 2 PCNB that promote effective disease management at acceptable monetary costs, without the environmental burden associated with PCNB use.

As part of the reregistration review of PCNB, BEAD conducted an assessment for the benefits and costs associated with PCNB and its alternatives for uses on golf course turf ( tees, greens, and fairways), cotton, potatoes, green beans, and three cole crops ( cabbage, Brussels sprouts, and cauliflower). These sites were identified by the Agency as the highest usage sites for PCNB in terms of percent crop treated and overall amount of active ingredient ( a. i.) applied ( according to EPA proprietary data and USDA National Agricultural Statistics Service). Although adverse environmental effects from PCNB use may be associated with other use sites ( including peanuts, peppers, dry beans, onions, ornamentals, and seed treatments of several crops), the crops examined in this assessment were considered to be of the highest priority for review.

Among the crop sites examined in this assessment ( golf course turf, cotton, potatoes, green beans, and cabbage, Brussels sprouts, and cauliflower), BEAD has identified effective and feasible alternative fungicides for treating diseases that currently can be treated with PCNB. The exception to this is the use of PCNB for treating clubroot of cabbage, Brussels sprouts, and cauliflower. There does not appear to be a chemical alternative to PCNB for this disease. Cultural practices, such as a seven year rotation or increase of soil pH, may not be sufficient or feasible alternatives if the causal pathogen is present in the soil. Otherwise, for the crops examined in this assessment ( except for clubroot of cole crops), all crop diseases that can be managed with PCNB are equally effectively managed with alternative fungicides.

Resistance management problems do not appear to be of concern for alternatives to PCNB. Generally, the typical once per season application of fungicides for the diseases examined in this assessment reduces the likelihood of pathogen resistance. In addition, for turf, the numerous alternative fungicides that are available have different modes of action and are generally tank mixed to allay pathogen resistance. In fact, there are reports ( see Johnston and Golob, 2003) that the pink snow mold pathogen has developed resistance to PCNB on a small number of sites with long time use of PCNB.

For turf, there are numerous alternative fungicides that are highly effective and economically feasible. For pink and gray snow mold treatment, for which PCNB is most commonly used, current recommendations from extension specialists, based on years of research, indicate that combinations of fungicides are more effective than individual products. While PCNB has been a mainstay for snow mold management, there are currently numerous fungicides available ( including azoxystrobin, fludioxonil, flutolanil, trifloxystrobin, propiconazole, iprodione, chlorothalonil), with different modes of action, that golf course superintendents can rely on to manage these diseases, at least as effectively as with PCNB. In addition, PCNB is known to cause phytotoxicity in some situations, while alternatives have not caused this problem.

For cotton, Rhizoctonia damping off control is the primary disease for which PCNB is used. BEAD assessed results of 26 fungicide trials conducted in several locations and over four growing seasons and identified azoxystrobin and iprodione as having at least comparable efficacy and cost to PCNB. 3 For potato, PCNB is primarily used to manage Rhizoctonia solani, but azoxystrobin and flutolanil are equally effective. In some locations, PCNB is used for control of white mold of potato, but boscalid, fluazinam, thiophanate methyl, and iprodione are equally effective. For both of these diseases, there are effective alternatives to PCNB at comparable costs.

For managing wirestem of cole crops, azoxystrobin is an effective and economical alternative to PCNB for field and transplant applications. In addition, fluidioxonil is a seed treatment that is effective and economically feasible for controlling wirestem disease. For managing clubroot of cole crops, PCNB appears to be the only available chemical treatment that is feasible for effective management of the disease where the pathogen occurs in soil. Cultural practices require a six or seven year rotation in non cruciferous crops and may not be a practical alternative for farmers who have infested acreage.

For managing white mold on green beans, effective and economical alternatives are boscalid, azoxystrobin or pyraclostrobin, dicloran, iprodione, and thiophanate methyl. For Rhizoctonia root and stem rots of green beans, effective and economical alternatives to PCNB are azoxystrobin or pyraclostrobin, iprodione, and chlorothalonil.

GOLF COURSE TURF ( Tees, Greens, and Fairways)

PCNB has been a long time treatment primarily for pink and gray snow molds, although it is labeled for some other turfgrass diseases as well  dollar spot, brown patch, large patch of Zoysia, and leaf spot. Use of PCNB for snow mold management constitutes the highest overall usage of PCNB in the U. S. ( EPA proprietary data and USDA NASS). It has provided reliable snow mold management options for golf courses troubled by these diseases and it is relatively inexpensive ( Nelson, 2004). Pathogen resistance to PCNB is not common, but has been observed in areas that have had high disease pressure and long time use of PCNB ( Johnston and Golob, 2003). Phytotoxicity resulting from PCNB treatments has been observed, especially when used at high rates or in warm weather ( Johnston and Golob, 2003; Schumann, 2003; Schumann, 2002; Vincelli, 2001). Research over the years has identified alternatives to PCNB and field trials have been published ( commonly in Fungicide and Nematicide Tests) defining fungicide programs that usually include two or three fungicides in combination.

Diseases The major diseases for which PCNB is used are pink snow mold ( Microdochium patch, Fusarium patch), caused by the fungal pathogen Microdochium nival and gray snow mold ( also called Typhula blight), caused by the fungi Typhula incarnata and T. ishikariensis. Snow molds occur in cool, moist conditions of alternating snow and rain ( Johnston and Golob, 2003; Vincelli and Powell, 2006; UI, 1997).

Other diseases for which PCNB is used are dollar spot ( Sclerotinia homoeocarp), brown patch ( Rhizoctonia solani, R. zeae), large patch of Zoysia ( R. solani) and leaf spot/ melting out ( Bipolaris spp. and Drechslera spp.). 4 Fungicides for Disease Management For both pink and gray snow molds, there are several combinations of fungicides that can provide equal or better efficacy compared to fungicide combinations that include PCNB ( usually used at rates less than the 16 lb PCNB per acre when PCNB is used alone). In additiion, combinations of fungicides without PCNB have greater efficacy than treatments with PCNB used alone ( Johnston and Golob, 2003; Schumann, 2003; Gregos and Jung, 2003; Li et al., 2003; Anderson et al., 2003; Schumann et al., 2002).

Tests conducted on established golf courses by golf course supervisors in five locations throughout Massachusetts, in the fall of 2002, found effective disease control with various combinations of fungicides, with and without PCNB ( Schumann, 2003). Based on trials conducted in 1995, 1996, 1999, 2000, and 2001 ( Schumann, 2003) several effective fungicide combinations were identified that effectively managed snow molds ( Table 1). The fungicide combinations reported by Schumann ( 2003) are similar to results reported by others ( Johnston and Golob, 2003; Gregos and Jung, 2003; Li et al., 2003; Anderson et al., 2003). To avoid phytotoxicity a tank mix of iprodione and chlorothalonil was considered as effective as PCNB for snow mold management ( Vincelli, 2006). 5 Table 1. Fungicide combinations and recommended rates of products that offer winter long protection from pink snow mold and gray snow mold without, and with, PCNBa Active ingredient( s) Product name ( rates per 1000 ft2) b Fungicide Treatment Without PCNB Propiconazole + Chlorothalonil Banner Maxx ( 3 fl oz) + Daconil 4F ( 8 fl oz) Propiconazole + Fludioxonil Banner Maxx ( 3 4 fl oz) + Medallion 50WP ( 0.5 oz) Propiconazole + Fludioxonil + Chlorothalonil Banner Maxx ( 3 4 fl oz) + Medallion 50WP ( 0.5 oz) + Daconil WS 6F ( 5.5 fl oz) Propiconazole + Flutolanil Banner MAXX ( 4 fl oz) + ProStar 70WP ( 4 or 6 oz) Propiconazole + Trifloxystrobin Banner MAXX ( 2 fl oz) + Compass 50WG ( 0.2 oz) Triadimefon + Flutolanil Bayleton 50WP ( 6 oz) + ProStar 70WP ( 4 oz) Triadimefon + Trifloxystrobin Bayleton 50WP ( 2 oz) + Compass 50WG ( 0.25 oz) Iprodione + Chlorothalonil Chipco 26019FLO 2F ( 4 fl oz) + Daconil 2787 4F ( 8 fl oz) Iprodione + Chlorothalonil Chipco 26019FLO 2F ( 4 fl oz) + Daconil Weather Stik 6F ( 5.5 fl oz) Iprodione + Chlorothalonil Chipco 26GT 2SC( 4 fl oz) + Daconil Weather Stik 6F ( 5.5 fl oz) Azoxystrobin + Propiconazole Heritage 50WDG ( 0.4 oz) + Banner MAXX ( 3 or 4 fl oz) Azoxystrobin + Propiconazole + Chlorothalonil Heritage 50WDG ( 0.4 oz) + Banner MAXX ( 2 fl oz) + Daconil Weather Stik 6F ( 5.5 fl oz) Azoxystrobin + Iprodione Heritage 50WG ( 0.4 oz) + Chipco 26GT 2SC ( 8 fl oz) Azoxystrobin + Chlorothalonil Heritage 50WG ( 0.4 oz) + Daconil Weatherstik 6F ( 8.0 fl oz) Azoxystrobin + Chlorothalonil Heritage 50WG ( 0.4 oz) + Daconil Ultrex 82.5WDG ( 3.2, 5, or 7.5 oz) Fludioxonil + Chlorothalonil Medallion 50WP ( 0.5 oz) + Daconil Weather Stik 6F ( 5.5 fl oz) ( Thiophanate methyl + chlorothalonil) Spectro Thiophanate methyl Topsin M Fungicide Treatment With PCNBc Propiconazole + PCNB Banner MAXX 1.24MEC ( 3 fl oz) + Turfcide 400 ( 9 fl oz) Triademefon + PCNB Bayleton 50WP ( 2 oz) + Turfcide 400 ( 10 fl oz) Triadimefon + Trifloxystrobin + PCNB Bayleton 50WP ( 2 oz) + Compass 50WG ( 0.25 oz) + Turfcide 400 ( 6 fl oz) Iprodione + Chlorothalonil + PCNB Chipco 26GT 2SC ( 4 fl oz) + Daconil Weather Stik 6F ( 5.5 fl oz) + Turfcide 400 ( 8 fl oz) Chlorothalonil + PCNB Daconil Weather Stik 6F ( 5.5 fl oz) + Turfcide 400 ( 8 fl oz) Chlorothalonil + PCNB Daconil Ultrex 82.5WDG ( 3.7 oz) + Turfcide 400 ( 9 fl oz) Chlorothalonil + PCNB Daconil Ultrex 82.5WDG ( 3.5 oz) + Turfcide 400 ( 8 fl oz) Azoxystrobin + PCNB Heritage 50WG ( 0.4 oz) + Turfcide ( 6 fl oz) Flutolanil + PCNB ProStar 70WP ( 4 oz) + Turfcide 400 ( 6 fl oz) ( Thiophanate methyl + chlorothalonil) + PCNB Spectro + Defend PCNB Used Alone PCNB Defend 75 WP ( 8 oz) (= 0.375 lb PCNB per 1000 ft2, or 16.335 lb/ acre) a Based on results from trials conducted in 1995, 1996, 1999, 2000, and 2001 ( Schumann, 2003). b Pesticide application rates for turf are typically calculated for 1000 square feet, rather than on a per acre basis. Multiply by 43.56 to calculate rate per acre. Rates shown are amount of product, not a. i. Since percent of a. i. in individual products vary, comparison of product amount requires calculating amount of a. i. for each product. c PCNB in combination with other fungicides is typically used at rates < 12 fl oz of product, which is equal to < 0.375 lb PCNB/ 1000 ft2 (= 16.335 lb per acre), based on 4 lb PCNB per gallon of product. 6 For treatment of diseases that may be treated with PCNB there are effective alternatives determined by extensive fungicide trials over several years. Based on performances of fungicides from 672 reports in Fungicide and Nematicide Tests, Vincelli ( 2006) rated the efficacy of ( mostly) individual fungicides for turf diseases in a University of Kentucky extension publication, Chemical Control of Turfgrass Diseases, 2006. While combinations of fungicides are frequently recommended ( see Schumann, 2003), these ratings provide an insight into comparative efficacy. Efficacy ratings were "++++" = excellent, "+++"= good to excellent, "++"= fair to good; ratings followed by " ½ " were intermediate between two categories. Alternatives were available for PCNB for all of the diseases.

For pink snow mold, fludioxonil was rated "++++", iprodione + chlorothalonil was rated "+++ ½ " ( as was PCNB), and several fungicides were rated "+++" ( iprodione, propiconazole, pyraclostrobin, thiophanate methyl, trifloxystrobin).

Vincelli states that " PCNB has proven to be an outstanding fungicide for controlling pink snow mold  However, application of PCNB has been shown to cause notable phytotoxicity to certain cultivars of creeping bentgrass and to Poa annua under some conditions. Superintendents can expect a similar level of disease control without the risk of phytotoxicity from a mixture of iprodione and chlorothalonil, each at their labeled rates. Indeed, the tank mix often provides a greater level of disease control than either product alone." See Table 1 for effective fungicide combinations for managing pink ( and gray) snow mold.

For gray snow mold, Vincelli states that " although gray snow mold is rarely a problem in Kentucky, this mixture [ iprodione + chlorothalonil] also controls that disease, should it occur."

For brown patch, there were several fungicides available that were rated "++++" ( e. g., azoxystrobin, pyraclostrobin, trifloxystrobin), "+++ ½ " ( fludioxonil, flutolanil, polyoxin D), or "+++" ( chlorothalonil, iprodione); PCNB was rated "++".

For dollar spot management, PCNB was not included in trials to a sufficient extent to receive an efficacy rating, but boscalid, myclobutanil, propiconazole, thiophanate methy, and triadimefon were rated "++++". Iprodione was rated "+++ ½ " , and chlorothalonil and fenarimol were rated "+++".

For large patch of Zoysia, which affects Bermudagrass as well as Zoysia, azoxystrobin, flutolanil, and triadimefon were rated "++++", as was PCNB.

For leaf spot/ melting out ( Bipolaris spp. and Drechslera spp.) iprodione was rated "++++" and azoxystrobin was rated "+++ ½ " . Chlorothalonil was rated "++ ½ " and PCNB was rated "++".

PCNB Use on Golf Course Turf Approximately 500,000 lbs of PCNB are applied to turf per year with application occurring predominantly in northern states ( EPA Proprietary Data). Though PCNB targets several pests, the majority of PCNB is applied to turf for control of snow mold. Table 2 shows the top ten states where PCNB is used. 7 Table 2. Leading States where PCNB is used on golf course turf State Percent of Total U. S Golf Courses that Apply PCNB Michigan 11% New York 9% California 8% Wisconsin 7% Washington 7% Minnesota 7% Ohio 7% Colorado 5% Pennsylvania 4% Oregon 4% Source: EPA Proprietary Data.

Costs of PCNB and Alternatives, and Golf Course Level Impacts The following focuses on the costs of PCNB alternatives that have been identified as providing equal or better control of the major pests controlled by PCNB and provides a summary of increased costs that might result from changing to these alternatives. The Agency's understanding of impacts to golf courses currently using PCNB is then provided. The primary focus of our analysis is on the control of snow mold, but many of the same pesticide products are used widely to control brown patch, dollar spot, large patch of Zoysia, and leaf spot/ melting out. Given that the control of these pests are relatively similar in cost to snow mold control, the conclusions drawn for snow mold control will apply generally to all PCNB use sites.

PCNB and other fungicides used for snow mold control are most effective when applied concurrently with other fungicide active ingredients. For this reason, the most informative measure available to compare the costs of PCNB and its alternatives is the cost of tank mixes of fungicides containing active ingredients that provide snow mold control. Table 3 shows pesticide costs, with and without PCNB, for selected tank mixes that provide effective snow mold control ( see Table 1). 8 Table 3. Cost of pesticide combinations for snow molds. Active Ingredient Tank Mix and use rate per 1,000 square feet Cost per 1,000 Square Feeta Propiconazole + Fludioxonil Banner Maxx ( 3 4 fl oz) + Medallion 50WP ( 0.5 oz) $ 17.70 Propiconazole + Fludioxonil + Chlorothalonil Banner Maxx ( 3 4 fl oz) + Medallion 50WP ( 0.5 oz) + Daconil WS 6F ( 5.5 fl oz) $ 21.20 Propiconazole + Flutolonil Banner MAXX ( 4 fl oz) + ProStar 70WP ( 4 or 6 oz) $ 26.05 Propiconazole + Trifloxystrobin Banner MAXX ( 2 fl oz) + Compass 50WG ( 0.2 oz) $ 9.95 Triadimefon + Flutolonil Bayleton 50WP ( 6 oz) + ProStar 70WP ( 4 oz) $ 40.60 Triadimefon + Trifloxystrobin Bayleton 50WP ( 2 oz) + Compass 50WG ( 0.25 oz) $ 15.25 Iprodione + Chlorothalonil Chipco 26019FLO 2F ( 4 fl oz) + Daconil 2787 4F ( 8 fl oz) $ 9.95 Iprodione + Chlorothalonil Chipco 26019FLO 2F ( 4 fl oz) + Daconil Weather Stik 6F ( 5.5 fl oz) $ 7.85 Azoxystrobin + Propiconazole Heritage 50WDG ( 0.4 oz) + Banner MAXX ( 3 or 4 fl oz) $ 20.20 Azoxystrobin + Propiconazole + Chlorothalonil Heritage 50WDG ( 0.4 oz) + Banner MAXX ( 2 fl oz) + Daconil Weather Stik 6F ( 5.5 fl oz) $ 19.75 Azoxystrobin + Iprodione Heritage 50WG ( 0.4 oz) + Chipco 26GT 2SC ( 8 fl oz) $ 19.65 Azoxystrobin + Chlorothalonil Heritage 50WG ( 0.4 oz) + Daconil Weatherstik 6F ( 8.0 fl oz) $ 16.10 Azoxystrobin + Chlorothalonil Heritage 50WG ( 0.4 oz) + Daconil Ultrex 82.5WDG ( 7.5 oz) $ 16.30 Fludioxonil + Chlorothalonil Medallion 50WP ( 0.5 oz) + Daconil WeatherStik 6F ( 5.5 fl oz) $ 12.00 Propiconazole + PCNB Banner MAXX 1.24MEC ( 3 fl oz) + Turfcide 400 ( 9 fl oz) $ 11.30 Triademefon + PCNB Bayleton 50WP ( 2 oz) + Turfcide 400 ( 10 fl oz) $ 13.15 Triadimefon + Trifloxystrobin + PCNB Bayleton 50WP ( 2 oz) + Compass 50WG ( 0.25 oz) + Turfcide 400 ( 6 fl oz) $ 17.50 Iprodione + Chlorothalonil + PCNB Chipco 26GT 2SC ( 4 fl oz) + Daconil Weather Stik 6F ( 5.5 fl oz) + Turfcide 400 ( 8 fl oz) $ 10.85 Chlorothalonil + PCNB Daconil Weather Stik 6F ( 5.5 fl oz) + Turfcide 400 ( 8 fl oz) $ 6.55 Chlorothalonil + PCNB Daconil Ultrex 82.5WDG ( 3.7 oz) + Turfcide 400 ( 9 fl oz) $ 6.00 Chlorothalonil + PCNB Daconil Ultrex 82.5WDG ( 3.5 oz) + Turfcide 400 ( 8 fl oz) $ 5.50 Azoxystrobin + PCNB Heritage 50WG ( 0.4 oz) + Turfcide ( 6 fl oz) $ 13.25 Flutolonil + PCNB ProStar 70WP ( 4 oz) + Turfcide 400 ( 6 fl oz) $ 14.75 Source: Cost data taken from EPA Proprietary Data. Rate information from Table 1. a Pesticide application rates for turf are typically calculated for 1000 square feet, rather than on a per acre basis. Multiply by 43.56 to calculate rate per acre. Rates shown are amount of product, not a. i. Since percent of a. i. in individual products vary, comparison of product amount requires calculating amount of a. i. for each product.

When adjusted for typical tank mix fungicide combinations and use rates typical of snow mold control, the predominant PCNB use site, tank mixes containing PCNB range in cost from $ 5.50 to $ 17.50, and alternatives that do not contain PCNB range in cost from $ 7.85 to $ 40.60. The cost of PCNB application is similar to many of the alternatives, though at the upper end of the cost range, alternatives are significantly more expensive.

Maintaining high quality playing surfaces is important for the golf industry's economic viability. However, the Agency does not, at present, have the necessary information to gauge the impacts of costs increases on representative golf courses or the golf industry. For this reason, our analysis of the economic impact of switching from PCNB to a PCNB alternative can not explicitly consider the direct impacts to golf course economic viability. Nonetheless, given that there are PCNB alternatives available that provide equal or better snow mold control at a 9 comparable cost, we anticipate that switching from PCNB to its alternatives will not significantly reduce the economic viability of golf courses using PCNB.

Conclusion BEAD has identified several effective fungicides that are alternatives to PCNB for managing pink and gray snow molds on tees, greens, and fairways of golf courses. Effective fungicide treatments without PCNB have been identified through numerous studies and are comprised of tank mixes of two or three fungicides of different chemistries. While PCNB can be an effective component of tank mixes to manage snow molds, other fungicides for tank mixing are available to golf course managers to manage these diseases as effectively as PCNB, and in several cases, more effectively than when PCNB is used. In addition, use of alternatives avoids the phytotoxic effects experienced in some turf cultivars ( Vincelli, 2006).

While successful disease management can be more difficult on tees and greens due to the intensively managed nature of these areas, there are several very effective fungicide alternatives to PCNB available to golf course superintendents for tees, greens, as well as fairways. In addition, there are effective fungicides available for the successful management of brown patch, dollar spot, large patch of Zoysia, and leaf spot. PCNB has been widely used because of relatively low costs. Several of the available PCNB alternatives are of a substantially higher cost than many combination products containing PCNB. However, there are also several alternatives that will result in similar or moderately higher costs than PCNB, and potentially provide more effective control and lower risk of turf damage due to phytoxicity. Given data limitations, we were unable to directly evaluate the impact of possible pesticide cost increases to the economic viability of golf courses. However, based on our evaluation of treatment costs and our finding that there are numerous available and similarly priced effective alternatives, we anticipate that if PCNB is no longer available, golf courses that currently use PCNB would not experience substantial negative impacts.

References for Golf Course Turf Anderson, M. A., Ross, R. B., and Tompkins, D. K. 2003. Fungicidal control of overwintering diseases in eastern British Columbia, Canada, 2001 2002. Fungicide and Nematicide Tests 58: T059.

Gregos, J. and Jung, G. 2003. Evaluation of fungicides for the control of pink snow mold and Typhula light in annual bluegrass, 2001 2002. Fungicide and Nematicide Tests 58: T019.

Johnston, W. J. and Golob, C. T. 2003. Snow mold control in the intermountain northwest. USGA [ United States Golf Association] Turfgrass and Environmental Research Online 2 ( 23): 1 9. http:// usgatero. msu. edu/ v02/ n23. pdf Li, D., Ross, J. B., and Tompkins, D. K. 2003. Snow mold control trials on creeping bentgrass in eastern British Columia, Canada, 2000 2001. Fungicide and Nematicide Tests 58: T058. 10 Nelson, M. 2004. Carving an edge in snow mold. United States Golf Association Green Section Record. March/ April ( 2004). http:// turf. lib. msu. edu/ 2000s/ 2004/ 040306. pdf Schumann, G. 2003. UMass snow mold fungicide trial results and real world results from superintendents 2002 2003. University of Massachusetts Extension. http:// www. umassturf. org/ publications/ online_ pubs/ snow_ mold_ summary_ 03. pdf Schumann, G. L., Anair, R., and Ebdon, J. S. 2002. Evaluation of fungicides and application timing for preventive control of snow mold on creeping bentgrass, 2000 2001. Fungicide and Nematicide Tests 57: T19.

UI ( University of Illinois). 1997. Reports on Plant Diseases: Snow molds of turfgrasses. RPD 404, UI Extension IPM. http:// www. ipm. uiuc. edu/ diseases/ series400/ rpd404/ index. html Vincelli, P. and Powell, A. J. 2006. Chemical control of turfgrass diseases 2006. University of Kentucky Extension Service. http:// www. ca. uky. edu/ agc/ pubs/ ppa/ ppa1/ ppa1. pdf Vincelli, P. 2001. More on phytotoxicity risk with PCNB. Kentucky Pest News, U. KY Extension. Dec. 10, 2001, number 938. http:// www. uky. edu/ Ag/ kpn/ kpn_ 01/ pn011210. htm# lawmor.

COTTON A total of 400,000 lb of PCNB were applied in furrow to cotton on 4% of the total acres in the U. S. ( USDA NASS, 1998 2001, 2003). It is most commonly used as an in furrow treatment applied to the soil as the planter is dropping seed. Azoxystrobin, iprodione, and PCNB are the three fungicides available for in furrow treatments for control of Rhizoctonia seedling disease. Fungicide resistance has not occurred for Rhizoctonia damping off of cotton and Rhizoctonia spp. are generally considered of low risk of developing resistance to fungicides ( FRAC, 2005). Therefore, fungicide efficacy is the main concern for farmers in attempting to manage this disease.

Rhizoctonia Seedling Disease PCNB has been used to manage Rhizoctonia seedling disease, which is a post emergence damping off disease caused by Rhizoctonia solani. It can be a problem for cotton growers in some locations, especially in the south ( UG, 2006; Mueller, 1996). This disease is primarily a problem when planting takes place in cool and wet weather and, therefore, may occur only in localized growing areas. Crop rotation might reduce populations of pathogens, and other cultural practices, such as a well prepared seedbed, which can help create optimal soil temperatures for planting to improve crop stands ( UT, 2005). However, common soil pathogens can infest rotation crops such as corn, peanut, and soybeans and growers usually rely on fungicide seed treatment and where needed, in furrow fungicide treatments ( Mueller, 1996). 11 Planting treated seed in optimal conditions greatly reduces the incidence of seedling diseases ( UG, 2006). Warmer temperatures and soils greatly increase germination and seedling emergence and reduce damping off incidences. In North Carolina, it was estimated that 5% losses occur in cotton due to the combined effects of various damping off diseases, including Rhizoctonia damping off ( Koenning, 2004).

Fungicides for Rhizoctonia Management Seed treatment. Fungicide seed treatment is standard practice for cotton seed, and can help to reduce the incidences of damping off diseases. Nearly all commercial cotton seed sold for planting is treated with fungicides to help manage damping off diseases ( Mueller, 1996). Several effective fungicides are available for cotton seed treatment for control of Rhizoctonia damping off, including carboxin ( Vitavax ® ) , carboxin + PCNB, triadimenol ( Baytan ® ) , triadimenol + thiram, 2( thiocyanomethylthio) benzothiazole ( Argent ® ) , chloroneb ( Nuflow ® M), fludioxonil ( Maxim ® ) , and azoxystrobin ( Protégé ® ) ( TAMU, 2005). In fungicide trials in Texas, " all fungicide treatments performed similarly and better than the seed without fungicide protection" ( TAMU, 2005).

In furrow treatment. Much research has been conducted on cotton to identify alternatives to PCNB for in furrow treatment of Rhizoctonia damping off. BEAD reviewed results of the 26 infurrow fungicide trials ( Table 4) published in Fungicide and Nematicide Tests from 2001 to 2005 ( see reference list for cotton, below) that compared the efficacy of azoxystrobin, iprodione, and PCNB against Rhizoctonia damping off. These 26 trials showed that azoxystrobin, iprodione, or both were at least as effective as PCNB in managing Rhizoctonia damping off in furrow based on seedling stand, skip index, and yield ( measured by either seed cotton or lint).

In furrow treatments involve application of a fungicide or tank mix of fungicides into the seed furrow while planting seed, followed by covering the seed with the treated soil. Depending on disease pressure and location, costs and benefits of in furrow treatments are calculated by farmers before planting. " As significant yield losses to seedling disease are sporadic in Georgia, the Cooperative Extension Service does not recognize the need for an additional fungicide treatment for each and every cotton field" ( UG, 2006). Research in Texas ( TAMU, 1996), the largest cotton growing state, suggests that the cost of in furrow fungicide treatment must be weighed with the likelihood of damping off disease for the expense to be warranted. " Cost of infurrows is generally higher, in the $ 10.00 per acre range, compared to approximately $ 2.00 per acre for two of the better seed treatments in combination. In furrows also have not outperformed the better seed treatments in tests on the High Plains" ( TAMU, 1996). Where high disease pressure is present ( frequently in wet locations), in furrow applications of fungicides appear to be useful ( UT, 2005).

For the fungicides available to treat Rhizoctonia damping off, azoxystrobin is typically used at rates ranging from 0.08 to 0.12 lb per acre. Iprodione is typically used at rates ranging from 0.16 to 0.20 lb per acre. PCNB is used at rates ranging from 1.0 to 1.5 lb per acre, with a season maximum of 2.0 lb per acre. 12 A product ( Messenger ® , EPA reg. no. 69834 2) containing 3% harpin protein was an in furrow treatment in six of the trials reviewed ( McLean et al., 2002a, 2002b, 2002d, 2002g, 2003a, 2003b). Results appeared promising, although the label does not include recommendations for in furrow application. In addition, water used for dilution has to be of such quality ( e. g., chlorine content, salts) not to de activate the product. Further testing may help define this product's usefulness for managing Rhizoctonia damping off.

Table 4. Comparison of efficacya against Rhizoctonia and other damping off diseases with azoxystrobin ( A), iprodione ( I), and PCNB ( P) for in furrow application in cotton based on plant stand, gaps in planted rows, and yield. Number Plant standb Skip indexc Yieldd ( lb/ Acre) Fungicide trial citation 1 ( Ae= If) > Pg Not tested Not tested Colyer and Vernon, 2003 2 A= I= P Not tested Not tested Colyer and Vernon, 2004a 3 A= I= P Not tested Not tested Colyer and Vernon, 2004b 4 ( A= P) > I A= I= P A= I= P ( seed cotton) Lawrence et al., 2004a 5 A= I= P A= I= P A= I= P ( seed cotton) Lawrence et al., 2004b 6 ( A= P) > I A= I= P A= I= P ( seed cotton) McLean et al., 2001 7 A= I= P A= I= P A= I= P ( seed cotton) McLean et al., 2002a 8 ( A= P) > I ( A= P) > I A= I= P ( seed cotton) McLean et al., 2002b 9 A= I= P A= I= P I > ( A= P) ( seed cotton) McLean et al., 2002c 10 A= I= P A= I= P A= I= P ( seed cotton) McLean et al., 2002d 11 A= I= P A= I= P I > ( A= P) ( seed cotton) McLean et al., 2002e 12 A= I= P A= I= P A= I= P ( seed cotton) McLean et al., 2002f 13 ( A= P) > I ( A= P) > ( A= I) ( A= P) > I ( seed cotton) McLean et al., 2002g 14 A= I= P A= I= P ( A= P) > ( P= I) ( seed cotton) McLean et al., 2003a 15 A= I= P A= I= P I > ( A= P) ( seed cotton) McLean et al., 2003b 16 ( A= P) > I ( A= P) > I ( A= P) > I ( seed cotton) McLean et al., 2003c 17 A= I= P A= I= P ( A= I) > P ( seed cotton) McLean et al., 2003d 18 A= I= P) Not tested A= I= P ( lint) Padgett and Price, 2001 19 A= I= P Not tested A= I= P ( lint) Padgett and Price, 2002 20 ( A= P) > I Not tested A= I= P ( lint) Padgett and Price, 2003 21h A= P Not tested A= P ( seed cotton) Padgett and Price, 2004 22h A= P Not tested A= P ( lint) Phipps and Maitland, 2002 23i I= P Not tested I= P ( lint) Phipps, 2004 24h A > P Not tested A > P ( lint) Phipps and Rideout, 2005a 25 A > I > P Not tested A > I > P ( lint) Phipps and Rideout, 2005b 26 ( A= I) > ( I= P) A= I= P A > ( I= P) ( seed cotton) Seebold and Horten, 2003 a Efficacy ratings are based on findings of statistical significance provided in the results reported in Fungicide and Nematicide ( F& N) Tests ( see References for Cotton section, below). b Number of plants in a defined row length  scale varies according to the trial. c Gaps within a row  scale varies according to the trial. d Based on yield of cotton seed or lint as specified ( in parentheses) for individual fungicide trials. e Azoxystrobin f Iprodione g PCNB h Iprodione was not included in this trial. i Azoxystrobin was not included in this trial.

U. S. Cotton Production Cotton is a major crop in the United States, with a total annual value of production averaging over $ 4.5 billion ( see Table 5). There are two varieties of cotton grown in the U. S. Upland 13 cotton is grown predominantly from Texas in the west, throughout the southeast to the Atlantic Coast, extending as far north as Kansas and Missouri. Pima cotton is a higher value, longer staple cotton grown in California, Texas, Arizona, and New Mexico. Table 5 shows the area harvested, production, and the value of production by state for both types of cotton, averaged over the years 2001   2005.

Table 5. Cotton are harvested, production and value: 2001 2005 ( average). State Area Harvested 1,000 Acres Production 1,000 Bales* Value of Production 1,000 Dollars Texas 4,810 5,955 1,221,090 Georgia 1,324 1,971 431,468 Mississippi 1,228 2,191 451,680 Arkansas 974 1,917 410,207 North Carolina 838 1,261 267,356 California 734 2,088 677,228 Louisiana 590 961 204,751 Tennessee 567 958 201,810 Alabama 548 795 167,303 Missouri 395 744 156,329 Arizona 242 649 148,033 South Carolina 239 338 73,504 Oklahoma 195 258 54,325 Florida 101 122 27,058 Virginia 92 152 30,906 Kansas 66 71 15,841 New Mexico 62 114 29,828 United States 13,003 20,547 4,568,718 Source: United States Department of Agriculture, National Agricultural Statistics Service: Crop Production 2003 Summary, Crop Production 2005 Summary, Crop Values 2003 Summary, Crop Values 2005 Summary. * A standard bale weighs 480 pounds. 14 PCNB Use on Cotton PCNB is a widely used fungicide in U. S. cotton production with the majority of PCNB use on cotton in past years centered in the southern and southeastern portion of the U. S. ( Table 6). This is where upland cotton is the dominant variety. Areas where PCNB is used in cotton production is in the USDA Farm Resource Regions of Eastern Uplands, Eastern Seaboard, and Mississippi Portal ( Farm Resource Regions, 2000).

Table 6. PCNB use in cotton by State: 1998, 1999, 2000, 2001, and 2003 average State Total A. I. Percent Crop Treated Number of Applications A. I. per Application A. I. per Year Mississippi 87,600 12 1.10 0.51 0.59 Arkansas 68,250 12 1.00 0.58 0.58 Alabama 65,500 17 1.05 0.63 0.67 Tennessee 62,500 17 1.00 0.64 0.65 Louisiana 48,670 11 1.03 0.68 0.73 Georgia 35,000 4 1.50 0.44 0.66 North Carolina 28,250 6 1.00 0.60 0.61 South Carolina 4,000 3 1.00 0.60 0.60 All Program States 399,800 4 1.02 0.59 0.63 Source: Agricultural Chemical Usage, Field Crop Summary, 1998, 1999, 2000, 2001, and 2003 ( USDA, NASS). Notes: Sum of States may not equal All Program States due to rounding. All Program States are those states that USDA NASS surveys for pesticide use on a given crop. They survey states that account for at least 80% of the total production.

Cost of PCNB and Alternatives Our analysis has found that there are two comparable alternatives to PCNB in furrow use in cotton that will provide, at minimum, equal control of the pests targeted by PCNB. These alternatives are azoxystrobin and iprodione. The per acre application rates and costs of PCNB and these alternatives are given below.

PCNB is typically applied in cotton at 0.5 to 1.0 Lb of a. i. per acre ( the label maximum application rate is 2 lbs a. i. per acre) ( USDA, NASS). Given per acre application costs of the product formulations under the brand names Ridomil and Terraclor, and typical application rates and use patterns in cotton production, the cost of PCNB is estimated to range from $ 6.00 to $ 7.50 with the typical per acre application cost at $ 6.50 per acre ( EPA Proprietary Data, and Mississippi State University, 2005).

Azoxystrobin is applied in cotton at 0.07 to 0. Under the 10 lbs a. i. per acre ( U. S. EPA Data). Given the per acre application costs of the product formulations under the brand names Quadris, and typical application rates and use patterns in cotton production, the per acre application cost of azoxystrobin is estimated to range from $ 9.00 to $ 11.50 with the typical per acre application cost at approximately $ 10.00 ( EPA Proprietary Data, and Mississippi State University, 2005). 15 Iprodione is applied in cotton at 0.14 to 0.17 lbs a. i. per acre ( EPA Proprietary Data). Given per acre application costs of the product formulations under the brand names Rovral, and typical application rates and use patterns in cotton production, the per acre cost of iprodione is estimated to range from $ 5.50 to $ 7.00 with the typical per acre application cost at approximately $ 6.50 ( EPA Proprietary Data, and Mississippi State University, 2005).

Grower Level Impacts This section provides the impacts that cotton producers would be expected to experience if PCNB is no longer available Information used in this assessment is based primarily on cost of production data from the USDA Economic Research Service, and covers the USDA Farm Resource Regions of Eastern Uplands, Eastern Seaboard, and Mississippi Portal, which are the areas where PCNB is most widely used in U. S. cotton production.

Our analysis assumes that there are equally effective alternatives to PCNB, and that there will be no yield or quality losses to growers that switch from PCNB to these alternatives. It is also assumed that there are no additional application costs that will arise from using alternatives instead of PCNB. Given these assumptions, changes in operating costs associated with using PCNB alternatives are the sole source of grower level impacts that could result if cotton producers switch from using PCNB to the identified alternatives.

Cotton producers receive revenue through the sale of cotton and through government support as authorized by the Farm Bill of 2002. Table 7 presents data describing the typical cost and returns resulting from the sale of cotton for cotton producers in the relevant Farm Resource Regions ( 2000).

Table 7. Cotton costs and returns per acre for southern seaboard, Mississippi portal, and eastern uplands production regions, 2003 and 2004 average Description / Production Region Southern Seaboard Mississippi Portal Eastern Uplands Total operating costs 324.8 413.09 287.12 Total costs 509.81 625.10 437.50 Yield, Cotton: ( pounds) 793.00 980.50 787.50 Yield, Cottonseed: ( pounds) 1283.00 1,587.00 1274.00 Revenue from Cotton 428.22 558.89 448.88 Revenue from Cottonseed 60.63 77.14 61.38 Total Revenue 488.85 636.02 510.26 Net Operating Revenue 164.05 222.93 223.14 Source: Cotton Production Costs and Returns per Planted Acre, Excluding Government payments, 2003 2004, USDA, Economic Research Service, http:// www. ers. usda. gov/ data/ CostsandReturns The portion of cotton producers' revenues derived from government payments are based on several factors. These factors are described below and are used in combination with cotton production data to estimate government payment by production region. Our estimates are based 16 on information from the United States Department of Agriculture, Economic Research Service ( USDA ERS).

Eligibility for payments is based on historical cotton yield and acreage. The base yield for the program is 93.5 percent of the 1998   2001 average, and base acreage is based on 85 percent of cotton acreage for the same time period. A cotton grower is eligible for government payments on 85% of their base acreage. For government payments, the yield on that base acreage is assumed to be 93.5% of the base yield. Because our estimates of the impacts are on a per acre basis, we approximate base yield and acreage by multiplying the average per acre yields ( shown in Table 7) by 0.935 for base yield and by multiplying that by 0.85 to approximate base yield on a per acre basis. This calculation gives the per acre pounds of cotton eligible for government payments.

We then approximate the value of government payments to cotton producers by subtracting the market price from the target price ( the target price equals $ 0.724 per pound for upland cotton). This number is then multiplied by the base yield ( on a per acre basis) and is a per acre approximation of government payments received by cotton producers. Cotton growers also receive direct and marketing loan program payments, but because the marketing loan price is generally close to the market price and because the market price rarely exceeds the target price, these payments are captured in the above calculations. Table 8 shows our estimates of government support payments for the relevant Farm Resource Regions.

Table 8. Estimated per acre government support payments to cotton producers, by farm resource region Description / Production Region Southern Seaboard Mississippi Portal Eastern Uplands Yield eligible for support payments 630.24 779.25 625.87 Difference between market price and target price 0.18 0.15 0.15 Per acre support payment 115.96 120.00 96.38 Note: Calculations were made using yield data shown in Table 7.

Grower level impacts of switching from PCNB to alternatives are measured on a per acre basis and are reflected in the change in a typical producer's net operating revenues ( net operating revenue is equal to total revenue minus operating costs). Changes in net operating revenues are shown in the Table 9. The information shows the impact of switching from PCNB to azoxystrobin because the per acre costs for PCNB and iprodione are approximately the same, which means that there are no measurable impacts of switching from PCNB to iprodione 17 Table 9. Farm level per acre impacts of switching from pcnb to azoxystrobin, by farm resource region Southern Seaboard PCNB Azoxystrobin Percentage Change1 Net Operating Revenue2 $ 164.05 $ 161.05  2% Net Operating Revenue ( Including Support Payments) 3 $ 280.01 $ 277.01  1% Mississippi Portal PCNB Azoxystrobin Percentage Change1 Net Operating Revenue2 $ 222.93 $ 219.93  1% Net Operating Revenue ( Including Support Payments) 3 $ 342.93 $ 339.93  1% Eastern Uplands PCNB Azoxystrobin Percentage Change1 Net Operating Revenue2 $ 223.14 $ 220.14  1% Net Operating Revenue ( Including Support Payments) 3 $ 319.52 $ 316.52  1% Source: Information shown in the table is based on operating cost and revenue data from Tables 7 and 8, and pesticide cost data from above section, " Cost of PCNB and Alternatives". Note: The per acre cost of iprodione is approximately the same as PCNB. For this reason, there are no measurable impacts of switching from PCNB to iprodione. 1. Percentage change represents the change from PCNB to Azoxystrobin. 2. " Net operating revenue" equals total revenue ( excluding government payments) minus operating costs. 3. " Net operating revenue ( including support payments)" equals total revenue ( including government payments) minus operating costs.

Given that azoxystrobin and iprodione are equally effective alternatives to PCNB, and that they are both similarly priced on a per acre basis to PCNB, we do not anticipate that the impacts of switching from PCNB to either alternative would be significant. In the case of iprodione, there are no measurable impacts. Though azoxystrobin is more costly on a per acre basis, the added costs would decrease net operating revenues by no more than 2% in any of the regions evaluated, and would lead to a reduction in net revenues ( including government support payments) by no more than 1% in any of the regions.

Conclusion Azoxystrobin, iprodione, and PCNB currently are the three choices of fungicides available to farmers for in furrow treatment of cotton for Rhizoctonia damping off. This assessment reviewed extension information and results of 26 published fungicide trials that were conducted over a four year period. These trials compared efficacy of azoxystrobin, iprodione, and PCNB and showed that, overall, azoxystrobin or iprodione were at least as effective as PCNB for disease management. Resistance to these fungicides is not a concern for managing Rhizoctonia damping off disease. Iprodione provided effective management of Rhizoctonia damping off at a cost similar to PCNB. Azoxystrobin is more expensive than PCNB but, when compared to 18 cotton producers overall economic situations, the anticipated impact of substituting azoxystrobin for PCNB is minor.

References for Cotton EPA Proprietary Data, 2002, 2003, and 2004.

Farm Resource Regions. 2000. USDA Economic Research Service. http:// www. ers. usda. gov/ publications/ aib760/

FRAC ( Fungicide Resistance Action Committee). 2005. Pathogen risk list ( Dec. 2005). http:// www. frac. info/ frac/ index. htm.

Koenning, S. 20004. Cotton seedling disease. North Carolina State University Plant Pathology Department. Cotton Disease Information Note No. 1. http:// www. ces. ncsu. edu/ depts/ pp/ notes/ Cotton/ cdin1/ cdin1. htm.

Mississippi State University, Department of Agricultural Economics, Budget Report 2005 01, December 2005, " Cotton 2006 Planning Budgets."

Mueller, J. D. 1996. Cotton seedling disease control. Clemson University Extension, Edisto Research & Education Center. www. clemson. edu/ edisto/ cotton/ seedling. pdf.

TAMU ( Texas A& M University). 1996. Plant pathology document. http:// plantpathology. tamu. edu/ Texlab/ Fiber/ Cotton/ cotton. html TAMU. 2005. Fungicidee Seed Treatments for Cotton. http:// ag cares. tamu. edu/ pdf/ fungseedtreatcot. pdf.

UG ( University of Georgia). 2006. Cotton disease and nematode management. 2006 Georgia Cotton Production Guide. Univ. Georgia Extension. http:// www. griffin. peachnet. edu/ caes/ cotton/ 2006cottonguide/ cottondiseasemanagement. pdf http:// www. griffin. peachnet. edu/ caes/ cotton/

USDA, ERS. 2002. Farm Bill, Title I, Commodity Programs. http:// www. ers. usda. gov/ Features/ Farmbill/ titles/ titleIcommodities. htm.

USDA, NASS. 1998, 1999, 2000, 2001, and 2003. Agricultural Chemical Usage, Field Crop Summary. http:// usda. mannlib. cornell. edu/ reports/ nassr/ other/ pcu bb/# field.

UT ( University of Tennessee). 2005. http:// www. utextension. utk. edu/ fieldCrops/ cotton/ cotton_ images/ 2005 cotton diseasecontrol pdf 19 Citations for in furrow fungicide trials published in Fungicide and Nematicide ( F& N) Tests:

Colyer, P. D. and Vernon P. R. 2003. Evaluation of fungicides for seedling disease control in cotton, 2002. F& N Tests 58: FC032.

Colyer, P. D. and Vernon P. R. 2004a. Evaluation of fungicides for seedling disease control in cotton on clay soil, 2003. F& N Tests 59: FC020.

Colyer, P. D. and Vernon P. R. 2004b. Evaluation of fungicides for seedling disease control in cotton, 2003. F& N Tests 59: FC019.

Lawrence, K. S., Jones, J. R., Usery, S. R., and Norris, B. E. 2004a. Evaluation of selected infurrow fungicides for management of cotton seedling disease in the Tennessee Valley region of Alabama, 2003. F& N Tests 59: ST024.

Lawrence, K. S., Jones, J. R., Usery, S. R., and Moore, D. 2004b. Evaluation of selected infurrow fungicides for management of cotton seedling disease in central Alabama, 2003. F& N Tests 59: ST023.

McLean, K. S., Campbell, H. L., Palmateer, A. and Moore, D. 2001. Evaluation of selected infurrow fungicides for control of Pythium spp. and Rhizoctonia solani seedling disease in central Alabama, 2000. F& N Tests 56: FC18.

McLean, K. S., Palmateer, A. J., Greer, N. W. and Moore, D. 2002a. Evaluation of in furrow fungicides for control of cotton seedling disease in central Alabama, 2001. F& N Tests 57: FC18.

McLean, K. S., Palmateer, A. J., Greer, N. W. and Moore, D. 2002b. Evaluation of in furrow fungicides for control of cotton seedling disease in central Alabama, 2001. F& N Tests 57: FC18.

McLean, K. S., Palmateer, A. J., Greer, N. W. and Moore, D. 2002c. Evaluation of selected infurrow fungicides for control of Rhizoctonia solani seedling disease of cotton in central Alabama, 2001. F& N Tests 57: FC25.

McLean, K. S., Palmateer, A. J. Greer, N. W. and Norris, B. E. 2002d. Evaluation of in furrow fungicides for control of seedling disease of cotton in north Alabama, 2001. F& N Tests 57: FC18.

McLean, K. S., Palmateer, A. J., Greer, N. W. and Moore, D. 2002e. Evaluation of Terraclor, Rovral, and Quadris for control of cotton seedling disease of cotton in central Alabama, 2001. F& N Tests 57: FC17. 20 McLean, K. S., Palmateer, A. J., Greer, N. W. and Moore, D. 2002f. Evaluation of in furrow fungicides for control of Rhizoctonia solani seedling disease of cotton in central Alabama, 2001. F& N Tests 57: FC16.

McLean, K. S., Palmateer, A. J., Greer, N. W., and Norris, B. E. 2002g. Evaluation of in furrow fungicides for Rhizoctonia solani seedling disease of cotton in north Alabama, 2001. F& N Tests 57: FC14.

McLean, K. S., Palmateer, A. J., Hutchinson, J. L., and Norris, B. E. 2003a. Evaluation of selected in furrow fungicides for management of cotton seedling disease in the Tennessee Valley region of Alabama, 2002. F& N Tests 58: FC010.

McLean, K. S., Palmateer, A. J., Hutchinson, J. L., and Moore, D. 2003b. Evaluation of selected in furrow fungicides for management of cotton seedling disease in central Alabama, 2002. F& N Tests 58: FC012.

McLean, K. S., Palmateer, A. J., Hutchinson, J. L., and Norris, B. E. 2003c. Evaluation of infurrow fungicides for management of Rhizoctonia solani seedling disease in the Tennessee Valley region of Alabama, 2002. F& N Tests 58: FC011.

McLean, K. S., Palmateer, A. J., Hutchinson, J. L., and Moore, D. 2003d. Evaluation of selected in furrow fungicides for management of Rhizoctonia solani seedling disease in the central Alabama, 2002. F& N Tests 58: FC013.

Padgett, G. B. and Price, J. L. 2001. In furrow and foliar fungicides for seedling disease management, 2000. F& N Tests 56: FC27.

Padgett, G. B. and Rea, W. 2002. In furrow or hopper box applications of fungicides for the management of seedling diseases, 2001. F& N Tests 57: FC30.

Padgett, G. B. and Rea, W. 2003. In furrow or hopper box applications of fungicide for the management of seedling diseases, 2002. F& N Tests 58: FC015.

Padgett, G. B. and Garber, B. C. W. 2004. Selected in furrow applied fungicides for seedling disease management in cotton, 2003. F& N Tests 59: FC005.

Phipps, P. M. and Maitland, J. C. 2002. Response of cotton to in furrow fungicide treatments at planting for seedling disease control, 2001. F& N Tests 57: FC28.

Phipps, P. M. 2004. Effect of seed treatments and in furrow fungicides on emergence, growth and yield of cotton, 2003. F& N Tests 59: FC070.

Phipps, P. M. and Rideout, S. L. 2005a. Effect of seed treatment and in furrow fungicide on emergence, growth and yield of cotton, 2004. F& N Tests 60: ST025. 21 Phipps, P. M. and Rideout, S. L. 2005b. Effect of in furrow fungicide treatments on seedling emergence, growth and yield of cotton, 2004. F& N Tests 60: ST081.

Seebold, K. W. and Horton, T. B. 2003. Evaluation of in furrow fungicides for the control of seedling diseases of cotton, 2002. F& N Tests 58: FC024.

POTATOES According to the U. S. Department of Agriculture, there were 200,000 pounds of PCNB applied to potatoes in 2003, and 85,000 were applied in 2001 ( USDA, NASS). Washington was the only major production state that used PCNB. PCNB use appears to be regional, with the most use in the northwestern U. S. PCNB was used on 38% of Washington potatoes and 3% of Idaho potatoes.

Two of the most important cultural means of managing potato diseases are crop rotation and use of clean potato seed pieces ( WPC, 2006). In Washington, typically crops are grown for one year and rotated out of potatoes for three years ( WPC, 2006). In addition, fungicide treatment of seed pieces helps create a healthy crop ( WPC, 2006). Treating seed pieces is essential to achieving healthy plants at emergence. Effective seed piece treatments include flutolanil + mancozeb ( Moncoat MZ), fludioxonil ( Maxim), fludioxonil + mancozeb ( Maxim MZ), thiophanate methyl + mancozeb ( Tops MZ) ( Zitter and Halseth, 2004). PCNB is not used for this purpose.

Diseases Managed with PCNB Stem canker and black scurf. PCNB is primarily used in furrow when planting potato seedpieces to manage the soil borne pathogen Rhizoctonia solani, cause of stem canker and black scurf. R. solani attacks tubers, underground stems, and stolons of potato plants ( Crop Profiles North Dakota, 2000). It is generally only a problem when seed potatoes are planted in cool, wet soils.

White mold. PCNB is used in some areas as a foliar application for suppression of white mold caused by Sclerotinia sclerotiorum, a pathogen with a wide host range. While this disease is not listed on standard PCNB labels as a target pest, there are Special Local Needs ( SLN) labels in effect for use of PCNB through chemigation in Washington, Nevada and Idaho.

The white mold pathogen overwinters in the soil as sclerotia. In spring the sclerotia germinate and produce spore forming structures ( apothecia), which infect potato leaves and stem ( OSU, 2005). Because of long term viability of the pathogen in the soil and its wide host range, crop rotations of four or more years with non host rotation crops ( e. g., corn) may be required to reduce inoculum where disease pressure has been high ( Maine, 1991; Olsen et al., 2003). Weed management to control weeds that are susceptible to the pathogen is also an important management strategy ( Olsen et al., 2003). The severity of the disease can be localized depending on conducive conditions ( primarily in moist conditions, including frequent irrigation ( WSU, 1994). According to Oregon State University ( OSU) extension, " Though widespread, and at times appearing to be quite damaging, the effect of yield is likely marginal in most fields, 22 particularly in the Columbia Basin" ( OSU, 2005). In addition, OSU extension states that " the disease must be severe for fungicide application to be economically effective" ( OSU, 2005). In cooler climates, white mold can be a significant problem if not properly managed ( Maine, 1991). Reducing humidity among plants by increasing spacing, decreasing vine growth, and irrigating less frequently can help reduce disease ( OSU, 2005; WSU, 1994).

Fungicide Alternatives to PCNB Seed piece fungicide treatment. PCNB is not used for seed piece treatment of potatoes, but treating seed pieces with labeled fungicides before planting is a common approach to preventing soil diseases of young potato plants. There are several fungicides that are effective in controlling Rhizoctonia, as well as other soil borne pathogens. According to Zitter and Halseth ( 2004), " with Rhizoctonia being a major concern, growers now have the option to select between several seed piece products. Moncoat MZ with the active ingredient flutolanil is very active for Rhizoctonia and provides safe control of Fusarium. The biological agent T 22 Planter Box ( Trichoderma harzianum) has good activity against Rhizoctonia, and may also suppress Pythium and Fusarium. Two additional products that extend the range of pathogens controlled are Tops MZ and Maxim MZ. Tops MZ relies upon the activity of thiophanate methyl plus mancozeb to provide activity against Rhizoctonia, Fusarium, and silver scurf ( Helminthosporium solani). This product has not performed as well as others for daughter tuber protection against silver scurf in tests conducted at Freeville. On the other hand, Maxim MZ ( active ingredient fludioxonil with mancozeb) has provided consistent control of Rhizoctonia, Fusarium, and silver scurf".

In furrow fungicide treatment for managing Rhizoctonia diseases. In furrow applications of fungicides are the major chemical means to manage black scurf and stem canker caused by R. solani. Azoxystrobin ( Amistar ® 80%, Quadris ® ) , flutolanil ( Moncut ® 70%), and PCNB were all rated " best" in an evaluation in New York ( Zitter and Halseth, 2004). No significant difference in yield was found between in furrow applications of azoxystrobin, flutolanil, and PCNB in a trial in Wisconsin ( Stevenson et al., 2004). According to Zitter and Halseth ( 2004), azoxystrobin, flutolanil, as well as PCNB have shown " excellent Rhizoctonia control". Zitter and Halseth ( 2004) have observed that some potato cultivars have delayed emergence with the highest rates of azoxystrobin.

Typical use rates ( Zitter, 2006) for in furrow application for azoxystrobin ( for a 36" row) range from 0.1 to 0.14 lb a. i. per acre. Flutolanil typically is used in furrow at rates ranging from 0.5 to 0.75 lb a. i. per acre. PCNB typically is used at rates ranging from 5 to 10 lb a. i. per acre.

Fungicide treatment applied to potato plants for managing white mold. Fungicide applications for white mold control generally are applied to base of plants or through chemigation, where allowed. If disease pressure is high, fungicides are usually recommended. For example, in Oregon ( OSU, 2005) ( Table 10) recommendations for fungicides when disease is likely include boscalid, fluazinam, iprodione, thiophanate methyl, and PCNB. DCNA is among recommended treatments and is currently undergoing reregistration. 23 Fluazinam has a multi site mode of action making it an excellent partner for alternating or tankmixing with site specific fungicides ( such as thiophanate methyl and iprodione), which may have higher rates of resistance to the white mold pathogen. PCNB has been used for this purpose, but fluazinam is an effective alternative with a lower risk of resistance development (. Michigan specialists ( Wharton and Kirk, 2005) recommend iprodione, fluazinam, azoxystrobin, thiophanate methyl, DCNA, and boscalid for managing white mold. A consortium of growers from Colorado, Nebraska, Wyoming, and Montana recommend boscalid, fluazinam, iprodione, and DCNA ( Schwartz and Gent, 2005).

Table 10. Recommended fungicides for management of white mold of potato in Oregon ( OSU, 2005). Fungicide A. I. ( Product) Rate ( lb a. i./ A) Maximum amount or applications per season REI ( hours) PHI ( days) Risk of Resistanceb Boscalid ( Endura ® ) 0.2 0.4 2 appl/ season 12 30 Medium Fluazinam ( Omega ® ) 0.18 0.26 1.8 lb a. i./ A/ season 48 14 Low Thiophanate methyl ( Topsin ® ) 0.7 1 2.8 lb/ A/ season 12 21 High Iprodione ( Rovral ® ) 1 4 appl/ season 24 14 Medium High PCNB ( Blocker ® ) 1.5 5 20 lb a. i./ A/ season 12 45 Low Medium a Oregon State University Extension ( OSU, 2005). b According to the National Potato Council, based on information from the Fungicide Resistance Action Committee, http:// www. nationalpotatocouncil. org/ NPC/ p_ documents/ document_ 210506110218. pdf.

Risk of Resistance to Fungicides The risk of Rhizoctonia developing resistance to fungicides is considered " low" ( FRAC, 2005) and the one time application at planting reduces pathogen exposure in the soil. The risk of Sclerotinia sclerotiorum developing resistance to fungicides is considered " medium" ( FRAC, 2005). Because there are several fungicides available for rotation throughout the season for white mold management, and because these alternative fungicides have different chemistries and modes of action ( including fluazinam with multi site activity), effective alternatives to PCNB can acceptably manage this disease without concern for development of pathogen resistance.

U. S. Potato Production and PCNB Use on Potatoes According to pesticide use data available from the USDA ( USDA, NASS), PCNB is used primarily in Washington Potato Production with minor use also occurring in Idaho. Surveys of pesticide use patterns further indicate that the primary use of PCNB is for control of black scurf/ stem canker. White mold suppression, though a secondary benefit of PCNB, is not the primary target pest ( EPA Proprietary Data). Table 11 provides potato production and PCNB use data for Idaho and Washington, the states where PCNB is predominantly used in potato production. 24 Table 11. Fall potato production and PCNB use in Idaho and Washington Data Idaho Washington Potato Production Harvested Acres 345,000 158,000 Yield ( CWT) 360 595 Production ( 1,000 CWT) 124,200 94,010 Price ( CWT) $ 4.65 $ 5.25 Value of production ( 1,000) $ 577,530 $ 493,552 PCNB Use Percent crop treated 3 38 Total a. i. Applied 10,000 184,000 A. i. per Application 1 1.77 Number of Applications 1 1.7 A. i. per Year 1.07 3 Source: Source: United States Department of Agriculture, National Agricultural Statistics Service: Crop Production 2003 Summary, Crop Production 2005 Summary, Crop Values 2003 Summary, Crop Values 2005 Summary, Agricultural Chemical Usage, Field Crop Summary, 2003, USDA, NASS.

Cost of PCNB and Alternatives Data for the average application rate and per acre cost of PCNB and its identified alternatives were taken from EPA data sources ( EPA Proprietary Data). PCNB is applied in potato production at an average rate of 1.80 lbs of a. i. per acre at an average cost of $ 16.30. Azoxystrobin is applied in potato production at an average rate of 0.11 lbs of a. i. per acre at an average cost of $ 15.05. Flutolanil is applied in potato production at an average rate of 0.54 lbs of a. i. per acre at an average cost of $ 23.00.

Grower Level Impacts This section provides the impacts that potato producers would be expected to experience if PCNB is no longer available.

This assessment focuses on Washington State because only 3 percent of Idaho potato acreage is treated with PCNB, and because the vast majority of PCNB use on potato ( approximately 95%) is in Washington. Information used in this assessment is based primarily on cost of production data from the State of Washington ( Hinman, H., G. Pelter, and E. Sorensen, 2001), production data from USDA ( USDA, NASS), and pesticide cost data from above.

Our analysis assumes that there are equally effective alternatives to PCNB, and that there will be no yield or quality losses to growers that switch from PCNB to these alternatives. It is also assumed that there are no additional application costs that will arise from using alternatives instead of PCNB. Given these assumptions, changes in operating costs associated with using PCNB alternatives are the sole source of grower level impacts that could result if potato producers switch from using PCNB to the identified alternatives. Grower level impacts of switching from PCNB to alternatives are measured on a per acre basis and are reflected in the change in a typical producer's net operating revenues ( net operating revenue is equal to total revenue minus operating costs). Table 12 provides a summary of the impact of switching from 25 PCNB to flutolanil. Note that low and high production cost scenarios represent the variation in production practices and costs associated with potatoes destined for the fresh and processed markets.

Table 12. Grower and state level impacts of switching from PCNB to flutolanil for control of black scurf/ stem canker Data Description PCNB Flutolanil Low Cost Production Scenario High Cost Production Scenario Low Cost Production Scenario High Cost Production Scenario Change In Pesticide Costs $ 0 $ 0 $ 7 $ 7 Total Operating Cost $ 1,644 $ 1,931 $ 1,651 $ 1,937 Initial Total Cost $ 2,374 $ 2,660 $ 2,380 $ 2,666 Yield ( CWT) 595 595 595 595 Total Revenue $ 3,124 $ 3,124 $ 3,124 $ 3,124 Net Operating Revenue $ 1,479 $ 1,193 $ 1,473 $ 1,186 % Change In Net Operating Revenue 0% 0% 0% 1% Source: Hinman, H., G. Pelter, and E. Sorensen, 2001, " Cost Of Producing Processing And Fresh Potatoes Under Center Pivot Irrigation Columbia Basin, Washington ( EB 1906)", Washington State University Cooperative Extension. United States Department of Agriculture, National Agricultural Statistics Service: Crop Production 2003 Summary and U. S. EPA Data Note: Low and high Production cost scenarios represent the variation in production practices and costs associated with potatoes destined for the fresh and processed markets.

Per acre application costs of flutolanil are higher than PCNB ($ 6.67 per acre). This added production cost reduces net operating revenues by 1% in the high cost scenario. This reduction is well outside the range of impacts that would typically reduce the economic viability of potato production.

Given that PCNB and azoxystrobin are similarly priced, with azoxystrobin being approximately $ 1 cheaper, the impact of switching from PCNB to azoxystrobin is minimal. The secondary benefit of mold suppression is, however, not included in this analysis and might explain why growers use PCNB instead of azoxystrobin at the present time.

Conclusion Azoxystrobin and flutolanil are fungicides that are effective for in furrow application to manage Rhizoctonia solani. These fungicides provide at least equal efficacy to in furrow applications of PCNB for managing R. solani in potato. For control of white mold of potato, several fungicides are available that are applied throughout the season to manage this disease. PCNB is considered suppressive of the pathogen Sclerotinia sclerotiorum and has not been the primary fungicide used for management of white mold. Changes in cost of potato production and its impact on net revenues are expected to be minimal with use of azoxystrobin or flutolanil, instead of PCNB. Based on our finding that effective alternatives are available for white mold control, we did not evaluate the benefit of white mold suppression capacity provided by PCNB. 26 References for Potatoes Crop Profiles Potatoes in Michigan. 2000. http:// www. ipmcenters. org/ cropprofiles/ docs/ MIPotato. html Crop Profiles Potatoes in North Dakota. 2000. http:// www. ipmcenters. org/ cropprofiles/ docs/ Ndpotatoes. html EPA Proprietary Data, 2002, 2003, and 2004.

FRAC ( Fungicide Resistance Action Committee). 2005. Pathogen risk list ( Dec. 2005). http:// www. frac. info/ frac/ index. htm.

Maine ( University of Maine). 1991. Potato Facts: White Mold. Extension Publication 2248. http:// www. umext. maine. edu/ onlinepubs/ htmpubs/ 2248. htm.

Olsen, N., Miller, J., Nolte, P., and Miller, T. 2003. White mold and potatoes. University of Idaho Extension Bulletin CIS 1105. http:// www. kimberly. uidaho. edu/ potatoes/ CIS1105. pdf.

OSU ( Oregon State University), 2005. Potato ( Solanum turberosum)  White mold ( Sclerotinia stem rot). Oregon State University Extension. http:// plantdisease ippc. orst. edu/ disease. cfm? recordID= 911.

Schwartz, H. F. and Gent, D. H. 2005. White mold. www. highplainsipm. org/ HpIPMSearch/ docs/ whitemold potato. htm.

Stevenson, W. R., James, R. V., Rand, R. E. 2004. Evaluation of the efficacy of seedpiece or infurrow fungicide treatment for potato disease control  Montello, WI, 2003. Fungicide and Nematicide ( F& N) Tests 59: V042.

Thomas, J. 2005. Response to inquiry from Western Integrated Pest Management Center. http:// www. wrpmc. ucdavis. edu/ NewsAlerts/ pcnbresponsepnw. pdf.

USDA, NASS. 2001 and 2003. Agricultural Chemical Usage, Field Crop Summary. http:// usda. mannlib. cornell. edu/ reports/ nassr/ other/ pcu bb/# field Wharton, P. and Kirk, W. 2005. White mold. Michigan State University Department of Plant Pathology. http:// www. potatodiseases. org/ whitemold. html.

WSU ( Washington State University). 1994. Sclerotinia stem rot on potato. Washington State University Extension Bulletin 1790. http:// cru. cahe. wsu. edu/ CEPublications/ eb1790/ eb1790. html Zitter, T. A. and Halseth, D. E. 2004. Potato seed piece and in furrow treatments for 2004. Cornell University Department of Plant Pathology. http:// vegetablemdonline. ppath. cornell. edu/ NewsArticles/ Pot_ Treat2004. html 27 Zitter, T. A. 2006. Potato fungicides ( labeled and rates/ A) as of March 23, 2006. Cornell University, Department of Plant Pathology. http:// vegetablemdonline. ppath. cornell. edu/ NewsArticles/ Pot_ LabeledRts. html COLE CROPS ( Cabbage, Brussels Sprouts and Cauliflower)

The term " cole" crops refers to plants in the crucifer family within the genus Brassica ( more specifically, varieties of the species Brassica oleracea) that have similar pest complexes. These crops include cabbage, collards, mustard greens, turnip greens, radish, broccoli, Brussels sprouts, cauliflower, Chinese cabbage, and kale. For this assessment, we have reviewed the management of two fungal diseases ( clubroot and wirestem) affecting cabbage, cauliflower and Brussels sprouts that are controlled by PCNB.

PCNB is labeled ( Table 13) for the control of clubroot ( caused by Plasmodiophora brassicae) disease and wirestem ( caused by Rhizoctonia solani). A one time per season application of PCNB is made at planting in furrow, as a transplant dip, or broadcast ( NY, 1999). Approximately 23,000 lbs of PCNB is used per on cabbage, Brussels sprouts and cauliflower.

Clubroot Disease. The infected roots enlarge, become distorted, and resemble clubs. The disease development on the roots of affected plants can be extensive before above ground portions show any symptoms. Leaves on infected plants turn yellow, wilt, and die. Clubroot can be a problem in cole crop production. Commonly less than 1% of the broccoli acreage in Michigan is affected with clubroot, but 100% yield losses can occur in infected acreage ( MI Crop Profile Broccoli, 1999). In New York, the largest cabbage producer, typical yield losses range from 1 15%, but can be as high as 50% in severely infested fields ( NY Crop Profiles, 1999). In California, approximately 1180 acres ( approximately 3 percent of total acreage of cauliflower) were treated with PCNB for the control of this pest during 1997 ( CA Crop Profile Cauliflower, 2000). The disease incidence and affected acreage varies from state to state.

Pathogen. This disease is caused by the fungus Plasmodiophora brassicae. The fungus gains entrance into the plant by attaching to the root hairs. As the fungus begins to develop in the roots, it produces spores. These spores are released and can be disseminated by water and infested soil. Acid soils and cool wet weather favor pathogen development. The disease is not seed borne.

Control. Location of the seedbed is important in clubroot management. To avoid local and wide spread distribution of the pathogen, the seed and transplant should be planted in diseasefree soil. Hydrated lime incorporated into the soil to raise the pH to 7.2 reduces clubroot; however, on muck soils the application of lime is of little value because of the high soil buffering capacity. Clubroot can be reduced by using PCNB fungicides as per label recommendations. These control programs should be coupled with crop rotation ( MN, 1999; WI, 2004). 28 PCNB is usually applied once at planting time. The recommended method of application for the control of clubroot is transplant solution [ 6 lbs/ A in 100 gallon water ( equal to 4.5 lbs ai)], band or broadcast application [ 15 40 lbs/ A in 25 to 50 gallon of water ( equal to 11 30 lbs ai/ A)].

Alternatives to PCNB for club root control. Clubroot disease incidence and severity can be reduced by PCNB. There is no other registered fungicide ( Table 13) that may reduce the disease ( Louws, 2005; NY Crop Profile Cabbage, 1999; MI Crop Profiles Cauliflower, 1999; HI, unknown date; MN, 1999; IL, 1989; Good, 2005; Lewis Ivey et al., 2004a, 2004b, 2004c). However, raising pH of the soil to 7.2 7.5 can prevent serious losses to the disease. The soil fumigants ( such as metam sodium and methyl bromide) control the disease ( Louws, 2005; NY Crop Profile Cabbage, 1999; MI Crop Profiles Cauliflower, 1999; HI, unknown date; MN, 1999; IL, 1989; Good, 2005; Lewis Ivey et al., 2004a, 2004b, 2004c; UW, 2004), but this may not be a feasible solution for small growers. Long crop rotation with non cruciferous crops ( 6 7 years) and raising soil pH to 7 2 7.5 have been recommended to reduce disease pressure and incidence, but these practices may not be commercially feasible options ( e. g., NY, 1999; IL, 1989).

Wirestem Disease: Wirestem gets its name from symptoms that occur on the stem at the soil level. A dark, water soaked lesion initially appears on the stem. Later stems become wiry and slender at the point of the lesion. This disease usually affects seedlings and newly transplanted plants, when disease pressure is high and plants are stressed due to inadequate soil moisture. The affected crucifer plants may grow poorly, are stunted and may eventually die. If infected plants remain alive, the stem becomes tough and woody. Plants that survive usually mature late and fail to produce a marketable head ( VA, 2000).

Pathogen: The pathogen ( Rhizoctonia solani) is present in the field soils and transplant seedlings may be infested without symptoms.

Control. Planting disease free transplants in well drained soils can reduce disease severity and incidence. If seed is planted rather than transplants, seed planted as shallow as possible, when soil temperature reaches 69 ° F ( 21 ° C) or higher, encourages rapid germination and emergence for plants to escape R. solani infections. PCNB can be used in the transplant dip water. However, according to NY Crop Profile for Cabbage ( 1999), yield losses are usually from damping off diseases early in plant development, rather than from the later development of wirestem. Soil fumigation of plant beds will eradicate Rhizoctonia solani; however, fumigated soil can become reinfested if pathogen infested field soil is moved to fumigated areas. For R. solani, PCNB is applied once as row or broadcast or drench at the time of or immediately after seeding ( 15 40 lbs/ A in 25 to 50 gallon of water, equal to 11 30 lbs ai/ A).

Alternatives to PCNB for wirestem control. Azoxystrobin is registered for use on cole crops in broadcast or band applications, or transplant drench for managing wirestem ( Table 13). Fludioxonil ( Maxim 4FS) is an effective seed treatment that protects seedlings against Rhizoctonia diseases. Azoxystrobin has been reported to reduce wirestem disease incidence on heading Brassica vegetables from 44% ( in infested control) to 0.05% ( Keinath et al., 2003). In another trial azoxystrobin reduced disease incidence from 19.5% ( in infested control) to 2.6% 29 ( Keinath et al., 2002). Shallow planting has been reported to reduce disease incidence by 50 90% ( Keinath et al., 2003; Keinath et al., 2004).

Table 13. PCNB and alternatives used on cole crops ( cabbage, califlower and Brussels sprouts).

Disease/ Pest Application method ( PCNB) Fungicide Alternatives ( Trade Name)* Application method ( Alternative s) Efficacy of Alternatives Clubroot ( Plasmodiophora brassicae) Transplant solution, Band and broadcast application, Row drench treatment No fungicide is registered as an alternative to PCNB. Metam sodium and methyl bromide ( soil fumigants) kill the pathogen, but may not be feasible due to cost or regulatory issues. NA Clubroot disease pathogen can only be controlled or suppressed using soil fumigants ( metam sodium and methyl bromide). Raising soil pH to 6.8 7.2 prevent serious losses to this disease ( Louws, 2005; NY Crop Profile Cabbage, 1999; MI Crop Profiles Cauliflower, 1999; HI, unknown date; MN, 1999; IL, 1989; Good, 2005). Transplant seedling must be disease free.

Azoxystrobin ( Amistar) Labeled for aerial & ground application and chemigation Wirestem ( Rhizoctoni solani) Band and Broadcast application, drench application Fludioxonil ( Maxim 4FS) Seed treatment Fludioxonil seed treatment and azoxystrobin ground application is reported to control this disease ( NY Crop Profile Cabbage, 1999; MI Crop Profiles Cauliflower, 1999; Keinath et al., 2002, 2003, 2004). Azoxystrobin alone has been found to control this disease very effectively ( Keinath et al., 2002, 2003, 2004).

Risk of Resistance to Fungicides The risk of Rhizoctonia developing resistance to fungicides is considered " low" ( FRAC, 2005). Presently, azoxystrobin is an effective alternative to PCNB for field application for the control of the wirestem pathogen with no reports of Rhizoctonia resistance in cole crops. There appear to be no reports of resistance to the seed treatment fludioxonil by Rhizoctonia. 30 U. S. Cole Crop Production Brussels sprouts and cauliflower are grown predominantly in California ( Table 14). Cabbage is grown throughout the U. S. with major production states including California, Florida, Georgia, New York, North Carolina, and Texas.

Table 14. Brussels sprouts, cabbage, and cauliflower area harvested, production, and value for 2005.1 Commodity State Acres Harvested Production 1,000 CWT Value of production 1,000 Dollars Brussels sprouts1 California 2,200 396 $ 14,471 Cabbage Arizona 3,100 1,395 $ 22,739 California 13,300 4,655 $ 70,291 Colorado 3,400 1,632 $ 15,504 Florida 7,800 2,652 $ 31,294 Georgia 10,000 2,800 $ 30,800 Illinois 750 236 $ 2,053 Michigan 1,400 630 $ 3,969 New Jersey 1,500 390 $ 6,942 New York 9,700 4,559 $ 67,289 North Carolina 6,500 1,430 $ 15,730 Ohio 1,400 252 $ 4,360 Pennsylvania 1,300 221 $ 4,022 Texas 8,700 2,610 $ 41,499 Virginia 750 169 $ 2,451 Wisconsin 4,100 615 $ 6,519 United States 73,700 24,246 $ 325,462 Cauliflower Arizona 4,700 1,010 $ 39,693 California 31,900 5,396 $ 154,377 New York 900 104 $ 3,349 United States 37,500 6,510 $ 197,419 Source: USDA National Agricultural Statistics Service  Quick Stats, U. S. & All States Data  Vegetables, 2001 and 2005. http:// www. nass. usda. gov: 8080/ QuickStats/ Create_ Federal_ All. jsp. 1. California is the major U. S. producer of Brussels sprouts. Production data collection for California Brussels sprouts was discontinued after 2001. Note: Data for Brussels Sprouts is for 2001. All other data is from 2005.

PCNB Use on Cole Crops We reviewed pesticide use data from the U. S. Department of Agriculture ( USDA NASS), California Pesticide Use Reports ( CA DPR, 2001 2004), and EPA pesticide use data ( EPA proprietary data) to identify PCNB use patterns in the cole crops. According to these sources, cabbage and Brussels sprouts are the only crops where PCNB has been used in recent years. Fewer than 5,000 lb of PCNB are applied annually in cabbage production, with the majority of the application occurring in New York ( EPA proprietary data). Approximately 5,000 lbs of PCNB are applied annually in California on Brussels sprouts ( CA DPR, 2001 2004). Use of PCNB in cabbage production has been predominantly for the control of clubroot ( EPA 31 Proprietary Data). The Agency does not, however, have pesticide use data that describes PCNB target pests in Brussels sprout production.

Cost of PCNB and Alternatives When used in furrow, PCNB is applied once per growing season and at a typical rate range of 6 15 lb per acre ( EPA Proprietary Data; NY, 1999) and can be applied in furrow at the same rate for both wirestem and clubroot. PCNB costs are approximately $ 60 150 per acre at $ 10 per pound ( EPA Proprietary Data).

Azoxystrobin has been identified as a PCNB alternative for the control of wirestem in cole crop production. For wirestem control, azoxystrobin would typically be applied once per year at a rate of 0.25 pounds per acre, and a cost of approximately $ 33 per acre, which is less than the $ 10 per pound required for PCNB.

Seed treatments using fludioxonil are also effective against wirestem in cole crops. However, at present, the Agency does not have adequate information to gauge the per acre cost of this control method.

Grower Level Impacts Based on our above review that there are no comparable alternatives to PCNB for the control of clubroot in cole crops. If PCNB is no longer available, we expect the impact on affected producers could be significant for fields with a history of clubroot disease. At present, cole crop production where PCNB is applied to treat clubroot can experience yield losses of up to 15% ( NY, 1999). As stated above, yield losses could approach 100% without PCNB in heavily infested fields. Losses of these magnitudes would be expected to lead to significant impacts to affected cole crop producers.

For managing wirestem disease, azoxystrobin provides as good, or better, control compared to PCNB, and at a lower cost. Seed treatment using fludioxonil also provide excellent control of wirestem. Given that there are effective treatments for this disease, and the finding of low reported use of PCNB ( EPA Proprietary Data), we do not anticipate that cole crop producers would experience significant adverse economic impacts as a result of using alternative wirestem disease management treatments instead of PCNB.

Conclusion PCNB may be important for the management of clubroot disease of cole crops where disease pressure is high and the growers can not fumigate their fields with metam sodium. Other fungicides do not appear to be effective in managing this disease. Cultural control methods, such as a long rotation ( 6 7 years) with non cruciferous crops, and changing soils to pH 7.2 7.5, may not be practical options for managing this disease under field conditions.

PCNB is not essential for the control of wirestem disease of cole crops since registered alternatives are at least equally effective in managing the disease. In addition, shallow planting 32 will further reduce R. solani disease incidence by 50 90 percent. Fludioxonil seed treatment provides additional protection to cole crops against this pest. Switching from PCNB to azoxystrobin and using fludioxonil treated seed will result in minor impacts, especially since PCNB appears to have limited use on these crops.

References for Cole Crops CA Crop Profile for Cauliflower. 2000. http:// cipm. ncsu. edu/ cropprofiles/ docs/ cacauliflower. html CA DPR ( California Department of Pesticide Regulation), California Pesticide Information Portal, 2001 2004, http:// calpip. cdpr. ca. gov/ cfdocs/ calpip/ prod/ main. cfm.

EPA Proprietary Data, 2002, 2003, and 2004.

FRAC ( Fungicide Resistance Action Committee). 2005. Pathogen risk list ( Dec. 2005). http:// www. frac. info/ frac/ index. htm.

Good, G. 2005. Cornell University comment through USDA. Seed and in furrow treatment is important against clubroot disease.

HI ( University of Hawaii) ( unknown date). Clubroot: Use clean and/ or treated seed. University of Hawaii Extension. http:// www. extento. hawaii. edu/ kbase/ reports/ recommendations/ colecrops. asp IL ( University of Illinois). 1989. Clubroot of cabbage and other crucifers. University of Illinois Extension Bulletin No. 923. http:// web. aces. uiuc. edu/ vista/ pdf_ pubs/ 923. PDF; http:// www. aces. uiuc. edu/ ipm/ fruits/ cole/ cole_ mgtrec. html# Club% 20Root Keinath, A. P., Dubose, V. B. May III. 2003. Evaluating soil applied fungicides to control wirestem on heading Brassica vegetables. F & N Tests Vol. 60: V003.

Keinath, A. P., Dubose, V. B. May III, W. H. and Cantrell, J. P. 2004. Evaluating new soilapplied fungicides to control wirestem on heading Brassica vegetables. F & N Tests Vol. 60: V038.

Keinath, A. P., Dubose, V. B., Cantrell and May III, W. H. 2002. Evaluating foliar applied fungicides to control wirestem on heading Brassica vegetables. F & N Tests Vol. 58: V010.

Lewis Ivey, M. L., Mera, J. R. and Miller S. A. 2004a. Evaluation of fungicides for the management of clubroot in mustard greens. F & N Tests Vol. 60: V100.

Lewis Ivey, M. L., Mera, J. R. and Miller S. A. 2004b. Evaluation of fungicides for the management of Rhizoctonia hypocotyls rot, clubroot and downy mildew in radishes. F & N Tests Vol. 60: V097. 33 Lewis Ivey, M. L., Mera, J. R. and Miller S. A. 2004c. Evaluation of fungicides for the management clubroot on radishes. F & N Tests Vol. 60: V098.

Louws, F. 2005. NC through USDA. PCNB is no. 1 choice for controlling clubroot and wire stem diseases and does not have any alternative.

MI Crop Profile for Broccoli. 1999. http:// www. cips. msu. edu/ cropprofiles/ Broccoli/ BroccoliInMichigan. html MI Crop Profile for Cauliflower. 1999. Http:// pestdata. ncsu. edu/ cropprofiles/ docs/ micauliflower. html MN ( University of Minnesota). 1999. Clubroot. University of Minnesota Extension. http:// www. extension. umn. edu/ distribution/ horticulture/ dg1169. html NY. 1999. Crop Profile Cabbage for New York. http:// www. ipmcenters. org/ cropprofiles/ docs/ nycabbage. html USDA NASS, 2005, Agricultural Chemical Usage, Vegetable Summary, http:// usda. mannlib. cornell. edu/ reports/ nassr/ other/ pcu bb/# vegetables.

VA ( Virginia Tech University). 2000. Wire Stem and Bottom Rot of Cabbage. Virginia Tech Cooperative Extension Publication Number: 450 713.. http:// www. ext. vt. edu/ pubs/ plantdiseasefs/ 450 713/ 450 713. html WI ( University of Wisconsin). 2004. Cole crops disorder: Clubroot. University of Wisconsin Extension Bulletin No. A1128. http:// cecommerce. uwex. edu/ pdfs/ A1128. pdf# search=' cole% 20crops% 20and% 20club% 20ro ot GREEN ( SNAP) BEANS Green bean, Phaseolus vulgaris, belongs to the Leguminosae, or pea, family. The seeds are planted when the soil temperature is above 62 degrees F in spring and summer. Spring crop snap beans are planted 1 to 1 1/ 2 inches deep after the beginning of the frost free period. Fall crop snap beans are planted early enough in the summer for harvest to be completed before the first killing frost. Row spacing for bush beans is 2 3 inches in the row and 18 to 36 inches between rows. The optimum temperature for plant growth is 60 to 70 degrees F. Snap beans require moist soil for germination. Water availability at pod fill is also critical to ensure high yields. Because of the relatively shallow root system of the snap bean the water requirement is high ( Mossler and Nesheim, 2000).

Approximately 30,000 lb PCNB are used per year to treat green beans ( EPA Proprietary Data). PCNB is labeled for the control of root/ stem rot ( caused by Rhizoctonia solani) and white mold 34 ( Sclerotinia sclerotiorum) diseases. The recommended PCNB application method for the control of R. solani is band row treatment directed spray in the seed furrow and to the covering soil at planting and in furrow application. For S. sclerotiorum, PCNB is applied once as a spray on bands centered on a row immediately after or at the time of planting. Later, sprays are directed to the soil at the base of plants. PCNB application rates are 2.75 lbs/ A ( equal to 2 lbs ai/ A) in 8 10 gallons of water.

White Mold Disease. White mold is caused by Sclerotinia sclerotiorum, it is also called sclerotinose, watery soft rot, and Sclerotinia rot of beans. It is one of the key diseases of snap beans during the cool season. The disease also affects vegetable crops, including potato, tomato, cabbage, celery, and lettuce, as well as wild hosts, particularly ragweed. Approximately 15 percent of snap bean acreage is affected with white mold in Florida ( Mossler and Nesheim, 2000).

The presence of small, black resting structures ( sclerotia) and a cottony, white mass ( mycelium) are characteristic of the pathogen. Sclerotia, which are able to survive between crop cycles, are the source of inoculum infesting individual fields from year to year. Usually, white mold in snap beans appears after the start of blossoming. The fungus enters senescent petals and from there moves into the plant, killing the stem above the infection point. The pathogen can also enter the plant through leaves or pods on the soil surface ( Mossler and Nesheim, 2000; Pernezny and Purdy, 1994).

Pathogen. This pathogen prefers cool and moist weather. The resulting disease is most severe at temperatures in the range of 60 to 70 ° F ( 15 to 21 ° C). The disease is spread most readily under conditions of high humidity with dew formation. Reduced air circulation due to close plant spacing or weed growth increases severity of the disease. Under sufficiently moist conditions, sclerotia in the soil produce infectious spores, which are carried in the air and splashing rain to host plants, initiating disease development upon germination. Sprinkler irrigation may favor disease development, and poor drainage can also increase white mold problems. Timing of fungicidal applications is critical. Essential time for treatment is during the blooming period, when the fungus attacks senescing flower petals ( Mossler and Nesheim, 2000; Pernezny and Purdy, 1994; Simone, 1998; Pernezny, 1997).

Control. PCNB is a protectant fungicide that snap bean growers apply at planting for the management of white mold disease.

Alternatives to PCNB. The other fungicides registered ( Table 15) for use on beans, for the control of white mold, are: dicloran ( Botran ® 75 W), pyraclostrobin ( Cabrio ® EG, Headline), boscalid ( Endure ® ) , iprodione ( Iprodione 4L AG, Rovral ® 75WG), azoxystrobin ( Quadris ® ) , thiophanate methyl ( Thiophante Methyl 85WDG). Under field conditions, boscalid, azoxystrobin and thiophanate methyl have been reported to reduce disease incidence and severity that equals or better than PCNB ( Strausbaugh and Koehn, 2003a; Strausbaugh and Koehn, 2003b; Strausbaugh et al., 2002; CA, 1999). 35 Rhizoctonia Root/ Stem Rot Disease. The disease causes postemergence damping off of the seedlings that is characterized by sharp edged oval to elliptical reddish brown lesions on the hypocotyl. Heavy infection may girdle the stem and the seedlings may die. Often the lesions heal over as the plant ages. Rhizoctonia root canker also occasionally occurs on the upper taproots of older plants as discrete, reddish brown lesions. The disease is most severe at 15 18 degrees C ( 60 65 F). Soil moisture has little effect on disease severity. Seedlings and young plants are susceptible to disease whereas the disease is rarely a problem on older plants. However, the pathogen can affect aerial parts of plants under high disease pressure.

Pathogen. The pathogen survives between crop seasons as sclerotia or mycelium in soil in or on infested plant debris or on perennial plants. It may be borne on or in bean seed. It is generally disseminated in infested soil or plant debris by wind, rain, irrigation water and farm equipment. When soils become infested, they remain so for many years.

Control. Cultural practices such as shallow seeding, rotation of beans with non host crops, and planting in warm soil may significantly reduce Rhizoctonia root rot. PCNB spray is applied once in the seed furrow and to the covering soil at planting time to control this disease. Metam sodium fumigation has also been recommended for heavily infested soils ( http:// cipm. ncsu. edu/ cropprofiles/ docs/ Cabeans green. html).

Alternatives to PCNB. Azoxystrobin, chlorothalonil, iprodione , pyraclostrobin and fludioxonil+ mefenoxam are registered for use on beans to control R. solani ( Table 15). Azoxystrobin, chlorothalonil and iprodione have been reported to be highly effective in controlling R. solani on beans when applied as foliar treatment to control root rot and aerial infections ( Kirk et al., 2000; Cody and Cubeta, 2001; Waldenmaier, 2004). Iprodione has been reported to be highly effective against this pathogen ( Spotts and Cervantes, 1996). Azoxystrobin + chlorothalonil treated plots had the least amount of root rot ( 77% disease) in comparison to the untreated control ( 100% disease) and other fungicide treatments ( Kirk et al., 2000). Azoxystrobin treatments also reduced R. solani infections on pea pod ( 71 92 percent). 36 Table 15. PCNB use on beans ( green) and alternative fungicides.

Disease/ Pest Application method ( PCNB) Fungicide Alternatives ( Trade Name)* Application method ( Alternatives) Efficacy Dicloran ( Botran 75 W) Chemigation Pyraclostrobin ( Cabrio EG, Headline) Ground and Air Boscalid ( Endure) Ground, air or sprinkler Irrigation Iprodione ( Iprodione 4L AG, Rovral 75WG) Ground, Air, spray to seed furrow and Chemigation Azoxystrobin ( Quadris) Ground Spray and drip chemigation White mold ( Sclerotinia sclerotiorum): Band, row and in seedfurrows Thiophanatemethyl ( Thiophante Methyl 85WDG Ground Spray Azoxystrobin, boscalid, iprodione, thiophanate methyl are effective against soil level and aerial infections of this pest ( Kucharek 2005; Gibbs, 2005; Mulrooney, 2005; Eaten, 2005; Louws, 2005; Toth, 2005; Mossler and Nesheim, 2000; simone, 1998; Pernezny and Purdy, 1994). The efficacy of these fungicides has been reported to be as good or sometimes better than PCNB in controlling the disease ( Kucharek 2005;, Strausbaugh and Koehn, 2003a; Strausbaugh and Koehn, 2003b; Strausbaugh et al., 2002). Iprodione has been reported to be highly effective against this pest ( Spotts and Cervantes, 1996).

Azoxystrobin ( Amister) In furrow and band application, Chemigation Chlorothalonil ( Equus 500ZN) Air, ground and chemigation Iprodione ( Iprodione 4L AG, Rovral 75WG) Ground, Air, spray to seed in furrow and Chemigation Pyraclostrobin ( Headline) In furrow, ground, air and chemigation Root/ Stem rot ( Rhizoctonia solani) Band, Row and infurrows Fludioxonil+ mefenoxam ( Apron Maxx RTA), Seed treatment, effective against R. solani, Pythium and Phytpphthora PCNB use is not critical to growers. A combination of alternative registered fungicides are likely to provide commercially acceptable disease control. In addition, cultural practices will further reduce disease incidence * Listed are US EPA registered fungicide alternatives on given crops. The registration was confirmed using http:// premier. cdms. net/ WebApls/ FormsLogin. asp?/ WebApls 37 Risk of Resistance to Fungicides The risk of Rhizoctonia developing resistance to fungicides is considered " low" ( FRAC, 2005). The risk of Sclerotinia sclerotiorum developing resistance to fungicides is considered " medium" ( FRAC, 2005). Because there are several fungicides available with different chemistries and modes of action ( Table 15) effective alternatives to PCNB appear to be available to acceptably manage both pathogens without pathogen resistance.

U. S. Snap Bean Production Snap beans are an important vegetable crop grown throughout the United States, with an average total value of production from 2003 to 2005 of approximately $ 400 million ( Table 16). Snap beans are grown for both the fresh and processing market in the U. S. Table 16 shows the area harvested, production, and the value of production for snap beans grown for both fresh consumption and processing by state for 2003 to 2005.

Table 16. U. S. snap bean ( fresh and processed) area harvested, production, and value: 2003   2005 average. Produced for the Fresh Market Produced for the Processing Market State Area Harvested ( Acres) Production ( Thousand CWT*) Value of Production ( Thousand Dollars) Area Harvested ( Acres) Production ( Thousand CWT*) Value of Production ( Thousands Dollars) California 6,367 637 $ 39,690 Delaware 2,900 9,250 $ 1,775 Florida 33,000 2,557 $ 142,158 2,100 9,300 $ 2,274 Georgia 16,833 800 $ 27,289 Illinois 14,833 58,847 $ 8,491 Indiana 5,800 17,390 $ 3,093 Maryland 1,667 48 $ 1,848 2,700 6,350 $ 1,288 Michigan 4,100 185 $ 5,858 17,933 56,250 $ 9,352 New Jersey 2,767 107 $ 4,858 New York 8,500 294 $ 21,233 21,167 70,887 $ 13,177 North Carolina 5,733 277 $ 8,997 Oregon 17,433 110,683 $ 20,120 Other States 38,470 137,760 $ 25,425 Pennsylvania 10,267 32,443 $ 6,938 South Carolina 1,100 47 $ 2,149 Tennessee 9,200 479 $ 15,913 Virginia 4,833 209 $ 6,166 1,000 2,850 $ 690 Wisconsin 71,600 301,587 $ 32,038 United States 94,100 5,640 $ 276,159 200,403 795,097 $ 120,643 Source: United States Department of Agriculture, National Agricultural Statistics Service:, Crop Production 2003 2005 Summaries and Crop Values 2003 2005.

* CWT indicates that the value is in 100 pound units. 38 PCNB Use on Snap Beans According to EPA Proprietary Data and USDA NASS, an annual average of 30,000 pounds of PCNB are used in snap bean production in the U. S. The majority of PCNB use in snap beans ( approximately 90%) is in Florida and Georgia. These are states that grow predominantly for the fresh market with Florida accounting for approximately 10% of total U. S. snap bean acreage and 35% of fresh market snap bean acreage, and Georgia accounting for approximately 5% of total U. S. snap bean acreage and 20% of fresh market snap bean acreage. PCNB is applied in these states at about 1 pound per acre and typically once per growing year ( USDA NASS).

Costs of PCNB and Alternatives Table 17 shows typical application rates and prices for PCNB and those active ingredients identified as alternatives for PCNB in snap bean production.

Table 17. Typical application rates and per acre costs for use of PCNB and alternatives in snap bean production. Active Ingredient Average Application Rate per Acre ( Lbs) Average Cost per Acre PCNB 0.90 $ 10 Azoxystrobin 0.15 $ 19 Boscalid 0.45 $ 83 Chlorothalonil 1.45 $ 11 Iprodione 0.80 $ 30 Thiophanate Methyl 1.05 $ 25 Source: EPA Proprietary Data, and USDA NASS.

Grower Level Impacts This section provides the impacts that snap bean producers would be expected to experience if PCNB is no longer available. Information used in our assessment is based primarily on cost of production data from Florida snap bean production for the fresh market ( Table 18). This is because budgets describing typical cost and returns to snap bean producers and other cost information covering Georgia snap bean production are not readily available. Total costs and operating costs will likely vary between Georgia and Florida, but because several of the available alternatives are similarly priced to PCNB, we do not anticipate significantly different impacts would be experienced in Georgia as in Florida, should PCNB no longer be available. Data sources covering fresh market snap bean production are used because fresh snap beans are the variety predominantly grown in both Georgia and Florida.

Our analysis assumes that there are equally effective alternatives to PCNB, and that there will be no yield or quality losses to growers that switch from PCNB to these alternatives. It is also assumed that there are no additional application costs that will arise from using alternatives instead of PCNB. Given these assumptions, changes in operating costs associated with using PCNB alternatives are the sole source of grower level impacts that could result if snap bean producers switch from using PCNB to the identified alternatives. 39 Grower level impacts of switching from PCNB to alternatives are measured on a per acre basis and are reflected in the change in a typical producer's net operating revenues ( net operating revenue is equal to total revenue minus operating costs) when using PCNB and alternatives. Changes in net operating revenues are shown in the table rows below entitled " Net Operating Revenue" and "% Change In Net Operating Revenue" for PCNB and each alternative. Other rows in the table show source information used in the calculation of net operating revenue.

Table 18. Florida farm level per acre impacts of switching from PCNB to alternatives in fresh snap bean production Category PCNB Azoxystrobin Boscalid Chlorothalonil Iprodione Thiophanate Methyl Change in fungicide costs $ 0 $ 9 $ 73 $ 1 $ 20 $ 15 Total Fungicide costs $ 161 $ 170 $ 234 $ 162 $ 181 $ 176 Total Operating Cost $ 1,553 $ 1,562 $ 1,626 $ 1,554 $ 1,573 $ 1,568 Total Costs $ 4,082 $ 4,091 $ 4,155 $ 4,083 $ 4,102 $ 4,098 Yield per Acre ( CWT) 78 78 78 78 78 78 Total Revenue $ 4,308 $ 4,308 $ 4,308 $ 4,308 $ 4,308 $ 4,308 Net Operating Revenue $ 2,755 $ 2,746 $ 2,682 $ 2,754 $ 2,735 $ 2,739 % Change in Net Operating Revenue 0% 0% 3% 0% 1% 1% Source: " Snap Beans: Estimated production costs in the Dade County area, 2004 2005," Cost of Production for Florida Vegetables 2004 05, University of Florida, http:// www. agbuscenter. ifas. ufl. edu/ cost/ and Yield and revenue data are 2003 2005 average taken from USDA NASS, Quick Stats Agricultural Statistics Database, U. S. and State Data, Vegetables, 2003 2005. http:// www. nass. usda. gov/ Data_ and_ Statistics/ Quick_ Stats/ index. asp. Note: Price of fresh snap per CWT is $ 55.60 and is a 2003   2005 average.

As reflected in Table 18, snap bean producers under typical Florida production systems, have very thin operating margins. However, because the cost of PCNB and its alternatives are similar in cost, using PCNB alternatives would be anticipated to have a minimal economic impact on snap bean producers. Of the five identified PCNB alternatives, the greatest impact would come from switching to boscalid from PCNB, and would result in a 3% reduction in net operating revenues. Use of other alternatives would result in a zero to 1% reduction in net operating revenues.

Conclusion For management of white mold on green beans there are several alternatives to PCNB available to farmers. Under field conditions, boscalid, azoxystrobin and thiophanate methyl have been reported to reduce white mold disease incidence and severity with equal, or greater, efficacy to PCNB.

For the management of Rhizoctonia root and stem rots on green beans, there are effective alternatives to PCNB. Azoxystrobin or pyraclostrobin, and iprodione are among the registered alternatives that are as effective as PCNB in managing the disease. 40 Green bean growers, under typical production systems, have thin operating margins. However, because the cost of PCNB and alternative fungicides are similar, there are likely to be minimal impacts on net revenues to these growers if alternatives are used instead of PCNB.

References for Beans:

CA. 1999. Crop Profile for Green Beans in California. http:// cipm. ncsu. edu/ cropprofiles/ docs/ Cabeans green. html Cody, B. R and Cubeta, M. A. 2001. Fungicide evaluation for snap bean pod rot. F & N Tests Vol. 57: V004.

Eaten, Alan. 2005. NH through USDA. Rotation or delayed planting will handle the problem. Approximately 5 acres are treated with PCNB in NH.

EPA Proprietary Data, 2002, 2003, and 2004.

FRAC ( Fungicide Resistance Action Committee). 2005. Pathogen risk list ( Dec. 2005). http:// www. frac. info/ frac/ index. htm.

Gibbs, Mac. 2005. NC through USDA. Some growers use PCNB+ mefenoxam for damping off. Some growers use azoxystrobin for damping off.

Kirk, W. W. Shaw, R. S and Schafer, R. L. 2000. Evaluation of foliar treatment for snap bean root rot. F & N Tests Vol. 56: V71.

Kucharek, Thomas. 2005. FL through USDA. PCNB used by some growers. It is not a dependable fungicide for the suppression of Rhizoctonia spp.

Louws, Frank. 2005. NC through USDA. Used occasionally on snap beans as a rescue treatment if high disease incidence.

Mossler, M. A. and Nesheim, O. N. 2000. Florida Crop/ Pest Management: Snap Beans. Florida Cooperative Extension Service Bulletin CR1231. http:// edis. ifas. ufl. edu/ PI032 Mulrooney, Bob. 2005. DE through USDA. Used against Rhizoctonia and Sclerotinia although there are alternatives such as azoxystrobin. PCNB is less prone to resistance.

Pernezny, K. and Purdy, L. H. ( 1994). Sclerotinia Diseases of Vegetable and Field Crops in Florida. Plant Pathology Fact Sheet PP 22. Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. http:// edis. ifas. ufl. edu/ scripts/ VH015 Pernezny, K. ( 1997). Controlling white mold and common bacterial blight. Citrus & Vegetable Magazine 62( 4): 26 27. 41 Simone, G. W. ( 1998). Disease Control in Beans: Bush, Lima, Pole, Wax ( Phaseolus spp.) and Southern Peas ( Vigna spp.). Plant Pathology PDMG V3 33. Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.

Spotts, R. A and Cervantes, L. A. 1996. Sclerotinia rot of pears in Oregon. Plant Disease 80: 1262 1264.

Strausbaugh, C. A and Koehn, A. C. 2003a. Control of white mold of dry beans with foliar sprays in Jerome County, ID. F & N Tests Vol. 59: FC001.

Strausbaugh, C. A and Koehn, A. C. 2003b. Control of white mold of dry beans with foliar sprays in Minidoka County, ID. F & N Tests Vol. 59: FC002.

Strausbaugh, C. A, Forster, R. L and Koehn, A. C. 2002. Control of white mold of dry beans with foliar sprays in Jerome County, ID. F & N Tests Vol. 58: FC52.

Toth, S. 2005. TN through USDA. Its in furrow use is important for protection against R. solani. No mention of alternatives.

USDA, NASS. 2000, 2002, and 2004. Agricultural Chemical Usage, Vegetable Summary. http:// usda. mannlib. cornell. edu/ reports/ nassr/ other/ pcu bb/.

Waldenmaier, C. M. 2004. Evaluation of fungicides for control of web blight in snap beans. F & N Tests Vol. 60 F & N Tests Vol. 087.