Learning the pest control triangle

Published 12:00 am Sunday, June 1, 2014

It takes three things to have a pest problem; a host, a pest, and the right conditions for the pest to, well, pester the host. I used to get a lot of mileage out of a little canned presentation I called The Pest Control Triangle. I borrowed the concept from plant pathologists who had drawn up the triangle for plant disease control. I merely expanded it to include bugs, deer and any other nuisance at any given time. The simplicity of the triangle is we have up to three choices to address pest control.
Folks very often control plant pests by focusing on the host without acknowledging any kind of triangle deal. The number one way they do that is simply not have the host around. That’s true when we say or hear, “We used to try to grow them, but they were too much trouble.” Roses get leaf spots, sweet corn gets worms and peach trees get everything. Just avoiding a host plant altogether is a surefire way to control its inherent pests at your place. Another host-based control method is to grow varieties of a plant species that has genetic resistance to certain pests. This is, or should be, the method of choice for dealing with most plant diseases. That VFN after the name of a tomato variety means the variety has the genes to fight off Verticillium and Fusarium wilt fungi as well as microscopic nematodes. The Knockout roses have joined many a landscape because of their black spot resistance. Just know there are quite a few other roses, some new, some real old that also handle black spot well.
Going after the “pest” point of the triangle does not always mean spraying something on the critters. Tall fences for deer, aluminum foil for cutworms and repellants for mosquitoes are control methods. So are beneficial predator insects, purple martins, bats and other natural debuggers. Pests can be trapped or swatted or chased off by a dog, sounds or bad odor. In commercial agriculture, insect birth control pills of a sort have helped a few times. When all else fails, that’s when we reach for the chemical or organic “cides”; fungicides, insecticides, miticides, etc.
The third “v” of the pest triangle is often the tough one we can’t win over. We can’t control our climatic conditions, but we can plan and plant within it. You want red top photina shrubs without their infamous fungal leaf spots? Plant those big boys in full sun, twelve feet apart on high ground, not crowded together in shady spots that don’t drain well. Plant sweet corn early to get kernels before the earworm moths fly in. Prune off lower tree limbs to get more sun in to a flowerbed. I estimate that ninety-seven-point-something percent of plants we grow for food or for their colorful blooms want lots of sun and good air circulation. It’s our job to keep host plants away from pest-prone conditions. Either change the conditions or change hosts.

Terry Rector writes for the Warren County Soil and Water Conservation District, 601-636-7679 ext. 3.

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