As the summer progresses, more and more plant-eating pests will find our gardens. Farmers and horticulture specialists call this build-up of unwanted insects and other creepy-crawlies “pest pressure”, and, in the South, it can become spectacular.
However, organic gardeners everywhere have a wide range of non-chemical strategies available to reduce pest-problems.
Simple pest control strategies for organic gardeners
Remove pests by hand
One of the simplest ways to deal with a whole assortment of plant-eating bugs and beetles is simply picking them off the plants and smashing them (possibly while wearing really good garden gloves) or knocking them into a little tub of soapy water, where they will drown. This strategy works for many kinds of beetles and bugs when the population of pests isn’t too large.
Mowing and weeding
Keeping the surrounding vegetation down helps reduce the number of places pests can hang out.
Spraying sturdy plants with a hard stream of water can knock smaller, soft-bodied insects like aphids off a plant. Very small insects can’t always manage to climb back up.
Placing fine mesh netting or a specially manufactured row cover over plants can keep them from being attacked by some kinds of insects. Especially if you want to keep an adult form from laying eggs that hatch into a destructive larva/caterpillar, this is a great strategy. I use netting over cabbage family plants to keep from getting cabbage worms and loopers on my crops.
Netting can also protect plants from birds and small mammals, if it is placed over-and-around the plants before the birds and mammals find your crop I get to eat a lot more of my own garden-strawberries when my plants are defended from chipmunks (my nemesis…) with heavy netting.
Organic-approved baits are available for some pests, like slugs, snails, and roly-polies (aka: sow bugs, pill bugs). These work, but patience may be required.
Bacillus thuringiensis (Bt)
This bacterial product is toxic to certain insects and is certified for use in organic gardens. The one I’ve used is the brand Thuricide, and it is for managing caterpillars. This includes those Cabbageworms and loopers, tomato fruit worms and hornworms, and cucumber pickleworms. It should also include Squash Vine Borers, but the success I’ve seen with these is patchy. For the vine borers, I have had better success when using several strategies together, rather than relying on just one (see link in “change the crop” section below).
Less simple pest control strategies
This next set of strategies includes practices that require either more thought or time or that require more than one “step” to complete.
Encourage beneficial insects (predators)
Many garden helpers, such as ladybugs, predatory wasps, and lacewings, are attracted to areas that have nectar-providing flowers nearby. Growing flowers like white clover, chives, hyssop, comfrey, or viper’s bugloss in the garden or in nearby areas can attract these helpers to your yard. Dandelions are another favorite.
The predatory insects also need a source of water, such as a very shallow birdbath that includes rocks or sand (to help them climb out, if they fall in).
Change the timing of your planting
Mexican Bean Beetles can strip all the green tissue off bean plants pretty quickly. They aren’t a problem every single year, but some years they totally halt production of beans in the garden because they’ve actually killed the plants.
These pests don’t typically become abundant in my garden, even in a “bad” year, until July. That means that early-planted bush beans have ample time to make a great crop and then be removed from the garden completely after the gardener has harvested plenty of beans for fresh use and more to either can or freeze for later use.
If your garden has had a couple of bad Mexican bean beetle years, this strategy can be a great work-around for the problem.
A similar strategy of changing the planting dates, based on when a particular pest seems to appear, can work for other crops, too.
Change the crop
Around mid-summer, gardens across the area are filled with wilted squash plants. Most of these plants are dying (or dead, with a gardener nearby holding a watering can and a hopeful expression on his or her face) from damage caused by the squash vine borer.
It turns out that we grow four main species of squash for food: Cucurbita pepo, Cucurbita mixta, Cucurbita maxima, and Cucurbita moschata. Of these, the C. pepo group contains most of the squashes we like to grow and eat: zucchini, summer squash, acorn squash, spaghetti squash, and most pumpkins. Sadly, this group is highly susceptible to squash vine borers.
The C. moschata group has the best resistance to the borers. The most familiar representative of this group may be the butternut squash, but this group also contains the cheese squashes, ‘Seminole Pumpkin’ squash, and a variety of squash sometimes called ‘Trombocino Rampicante’ (sometimes also called ‘Zucchetta’) that, when immature, is somewhat similar to zucchini.
Most of the C. moschata plants can grow to sprawl across 20-30 feet of garden. Gardeners working in smaller spaces can look for a dwarf version, like a dwarf butternut.
Not all insects are pests
For new gardeners, becoming comfortable with the universe of insects that inhabit the garden can take some time. It might help to remember that some of these creepy-crawlies are working with you, not against you.
Some insects are the pollinators that help your crops make delicious food for you to bring into the kitchen. Pollinators include many kinds of bees, butterflies, wasps, beetles, and flies.
The babies of butterflies are caterpillars, which do eat plants. This means that gardeners should determine some level of acceptable damage, not killing every caterpillar on sight, so we will have plenty of butterflies. Planting some crops specifically for caterpillars may help.
The ones that are wimpy eaters
Some insects that eat plants never become abundant enough to keep your plants from making good food. The caterpillar called the bean leaf roller is usually one of these. These may not be “garden helpers” like some of the other creepy-crawlies, but they aren’t exactly the bad guys, either. I usually leave these alone.
Becoming familiar with the predators (wasps, ladybugs, lacewings, and their babies) can help you avoid killing them by mistake. Of course, the predators are not all super-choosy about their prey, so some of them may eat others of your beneficial insects. Try not to worry about that too much.
The caterpillar covered with wasp eggs in the picture nearby is a saddleback caterpillar. This type of caterpillar has stinging hairs that are very unpleasant for people to encounter.