Gardener: Pest control, done naturally, restores order


Gardening is about balance. Light, nutrients, temperature and moisture all work together to make a proper environment for plants to thrive. Gardens are a microcosm where bacteria, earthworms and countless other organisms go about their business, usually in harmony, with the good critters policing the thugs.

Imbalance creates conditions that let the hoodlums exploit the others. That's where IPM ---- integrated pest management ---- comes in to help restore and maintain balance and order.

During World War II, pesticides became the magic bullet that would save the world from insects. The chemists didn't count on bugs' ability to develop chemical resistance. By the 1960s, the magic bullets were missing more than they were hitting, and causing as many problems as they were solving.

That's when entomologists came up with the idea of integrated pest management, steps designed to deal with pest problems starting with the most benign. IPM is holistic gardening: You first gather all the facts about the landscape and everything going on within it, then decide on the best steps for any problems. They may include spraying a botanical pesticide, changing cultural practices, altering a microclimate or, as a last resort, applying chemicals. But nothing is done blindly.

Here's how to size your garden up for IPM:

1. Decide at what point you must act based on your personal level of tolerance: Just how infested and damaged can a plant get before you can't stand it anymore? Decide whether to save or toss it.

2. Understand the possible pests your plants will face, when to act and the guidelines for what to do. County extension services, horticultural schools, universities and nurseries are great resources. They have experience with all the local problems and their solutions.

3. Monitor the situation. I patrol my garden every day when possible to check for the beginning signs of problems. I turn over foliage and inspect for eggs and disease damage, and check for secondary signs, such as yellowing leaves or black sooty mold. Take samples and pictures and record your findings in a notebook. You must be sure of what's causing the problem so you'll apply the right cure at the right time.

4. Use your findings to keep pests in line. The more methods you can put to work, the better. That's the "integrated" part of IPM. Some problems may only require changes in culture. Rhododendrons are vulnerable to phytophthora root rot, so moving them to a dryer location or reducing watering could eliminate the wet soil where that fungus thrives. Flowering crab apples and junipers both share cedar-apple-rust fungi, so keep them separated in the landscape.

You may need to choose a specific pesticide. For me, that means non-synthetic, biological controls. Three products can take care of most problems if and when applied appropriately: Bacillus thuringiensis (commonly known as Bt) targets leaf- and flower-eating caterpillars. Insecticidal soap goes after sucking insects like aphids, spider mites and mealy bugs. Neem oil gets leaf chewers like cutworms and Japanese beetles.

With all, follow label directions and apply at the correct stage in the pest's lifecycle. Spray only the affected plants.

5. Monitor carefully to see if your IPM has been effective, and make changes as necessary. Head off problems before they start. Design your landscape with plants adapted to your climate. Build diversity with lots of species and choose resistant varieties.

Understanding and working with nature will always yield better, more satisfying results.


