Tuesday, June 16, 2009

Pest Control: Prevention

I tend to not use pesticides in my garden, even the approved-for-use-in-organic-gardens ones. I have always been concerned that I would accidentally kill some helpful critters, the pollinators and predators, along with the unwanted, plant-destroying critters.

These are my main methods of pest and disease control:

1. choosing to grow disease and pest resistant varieties

Growing VF-resistant tomatoes means that my garden will produce tomatoes even in very wet years. V and F stand for verticillium and fusarium; these are fungal “wilt” diseases that lurk as spores in soil all across north Georgia—and beyond! Unfortunately, other plants in the tomato family (Solanaceae) are not strongly resistant.

If my tomatoes routinely succumbed to Early Blight, I would look for blight-resistant tomatoes, but, so far, that hasn’t been a problem.

Growing the Cucurbita moschata (example: trombocino) species of squash in addition to Cucurbita pepo (example: zucchini) is a way to avoid losing all the squash to the squash vine borers, which routinely kill members of the C. pepo species.

2. growing plants that might not be disease-resistant in pots, in commercial potting soil

The yellow marble cherry tomato is in a very big pot because I couldn’t find any information about its disease resistance (or lack there-of). A friend gave me a Japanese Trifle tomato, and it is also in a pot—same reason.

3. using fabric barriers to exclude pests from susceptible plants

Growing cabbage family plants under fabric row-covers, either the Remay-type, available through garden-supply stores, or tulle, available at fabric stores in the bridal area, keeps those white cabbage moths from laying eggs on the plants, which keeps those caterpillars from eating the plants before the gardener does.

This year I am also experimenting with keeping some of my cucumbers covered at night, to exclude the night-flying moth that is parent to the cucumber pickleworm.

4. working to improve the soil so that my plants are as healthy as I can help them to be

Amending with plenty of organic matter (my own compost, plus bagged soil conditioner) helps improve the soil structure. Plants do better when their roots are not in soil that turns into soggy playdough in Spring or bakes to brick-hardness in Summer. It is also important to keep an eye on soil pH. Most garden vegetables do best with a soil pH around 6-6.5. One big exception is potatoes, which do well at a much lower pH, closer to 5.

5. rotating crops through the garden, so that plants in one family are not grown in the same place two years in a row (more years in between than just one is preferable)

Keeping a family of plants from growing over and over in the same soil is important in limiting the buildup of diseases and pests that affect that family. Unfortunately, my garden is small, so crop rotation for me is complex and less-than-perfect. I usually manage a three-year rotation, but sometimes, in some parts of the garden, I only manage to alternate years.

This is partly why I have more plants in pots than I used to; they help me keep the peppers and eggplants out of the standard rotation, so that it is easier to keep members of the Solanaceae (tomatoes, peppers, eggplants, potatoes), for example, from growing in the same place within that three years.

This also is part of why I’ve expanded my food growing to crops that my family may be less familiar with (or enthusiastic about!) but that are in plant families other than the tomato, squash, and bean families. Chard is one example. It is in the same family as spinach and beets.

6. patrolling the garden, watching for problems

Keeping a watch for problems is an important part of any attempt to limit damage in the garden. For example, noticing an infestation of squash bugs when there are just a few platoons of tiny, immature nymphs means that a gardener has a better chance to limit the damage than if those nymphs all reach maturity, do serious damage to the plants, and then reproduce by the thousands to compound that damage.

For large insects, knocking the pests into a bucket of soapy water drowns them, putting an end to their pestiferous ways and to their reproduction in my garden. This works really well for Japanese beetles, squash bugs, and Mexican bean beetles. For little critters like the flea beetles that can turn eggplant leaves into sad scraps of torn lace, I catch the little critters between a finger and thumb and just roll them around until I am sure they are dead or at least severely damaged. Sound heartless, I know, but it is the insects or my plants…



Some of these methods of control are feasible only because my garden is small. If I had a very large garden, or if my family’s winter-eating absolutely depended on the production of my garden, I would probably look a bit more closely at the approved-for-use-in-organic-gardens pest products, and then use them.

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