We have an old crape myrtle that has black, sooty mold on a large portion of the leaves. I have never had this before. What could be causing it?


This popular landscape tree tends to be more disease- and pest-free than many of the plants available for enhancing our homes and gardens.

There are two primary culprits that affect the trees: powdery mildew, which is more whitish in color, and the crape myrtle aphid, which causes the sooty mold. This species of aphids is only found on crape myrtles. Their feeding on the underside of the leaves produces a sugary honeydew that falls to the leaves below which, in turn, promotes sooty mold fungi growth. In North Florida, the population of these aphids peaks between late June and early August — so they have probably been feeding on your tree for several weeks.

The population explosion of aphids at this time makes it difficult for their predators to keep their numbers in check. This time of year, the best recommendation for homeowner control would be to use an insecticidal soap. Spray in the cooler part of the day. Horticultural oils can be used in cooler weather.

Keep in mind that sooty mold and aphids won’t kill your crape myrtle, but they can affect the tree’s vigor. As the aphid populations decrease, so will the sooty mold. And, as winter approaches, the tree will go dormant and drop its leaves.

Next year, start scouting for these insects in May and June. The earlier these insects are detected, the easier it is to control them.

We planted a temple orange tree a few years ago. The fruit is always dry. What should we do?

This phenomenon is called granulation or drying of the fruit sacs. The condition is more common on larger size fruit-bearing trees such as navels or Hamlins or grapefruits. It is also common on late-blooming fruit.

Granulation can also result from inadequate water, over-fertilization, warm and/or dry fall weather, and is more common in young trees. In your case, I think the most logical suspect is the variety itself. The harvest time for temple oranges is typically late in the mid-season, or January to March. This orange is not usually recommended for planting in North Florida because of its later harvest time.

Because the temple is one of your favorites, you can give it another few years to see if the condition improves. Otherwise, you might need to replant a more suitable tree.

The University of Florida publication, “Citrus Culture in the Home Landscape” (found at ufl.edu) has detailed information on the harvest time for common and specialty citrus cultivars.

I planted several types of vegetable seeds this past spring. Most of them did not come up. What do you think I did wrong?

There are several factors that can affect seed germination — or lack thereof. First, if planted too early, cool or cold soil temperatures could affect germination. Next, always start with fresh seed. As seeds age, they lose their viability.

Don’t plant your seeds too deep. Avoid planting any deeper than twice the width of the seed. The smaller the seed, the more shallow it is planted.

Seeds need moisture to germinate. If left to dry out, they will not germinate. Conversely, avoid drowning the seeds. Overwatering can rot the seeds or promote disease.

Garden pests such as mole crickets and wildlife such as birds can seek out the seeds for food. Mole cricket baits might help. If birds are a real problem, you can try some bird netting during the initial germination period. Keep these practices in mind when planting your garden this fall or next spring.

I want to plant a vegetable garden, but I don’t think I have enough sun. What can I plant in an area that gets 3 to 5 hours of full sun?

Most of our fruit-bearing vegetable plants and trees need 6 to 8 hours of full sun to give you a productive crop. If you have less sun, try your hand at leafy vegetables such as lettuces, spinach, and other salad greens. They perform well in shadier spots. In warmer weather, the shade will help them last a bit longer before bolting and going to seed.

Cooking greens such as mustards, collards, kale, chard and the like will tolerate some shade, although they won’t grow as large as they would in full sun. Root vegetables such as carrots and beets perform pretty well in 4 to 5 hours of sun.

Some of our cooler season vegetables such as broccoli and cauliflower will tolerate less sun. Same goes for cool-season peas and bush beans. A host of herbs both cool and warm season produce well in less than a full day of sun.

For more information, go to ufl.edu and search for the publications titled “The Florida Vegetable Gardening Guide and Herbs in the Florida Garden.”
