In the Garden: Pests can be thwarted naturally

I enjoy growing a large vegetable garden, yet rarely have serious insect problems. That’s because I have a lot of helpers in the form of birds and beneficial insects that I intentionally attract. I also avoid using chemicals that can kill both the bad bugs and the good, throwing the ecology of my garden out of balance.

Insects such as cabbage loopers, aphids, slugs, leaf miners and stink bugs can be a challenge, but all can be dealt with organically.

Those green inchworms known as cabbage loopers love nothing better than munching on cabbage family crops such as broccoli, Brussels sprouts, cauliflower and kale. There are two strategies to prevent cabbage butterflies from laying eggs on them.

The first involves covering plants with floating row cover. This lightweight fabric is used as a physical barrier and, since none of these crops needs to be pollinated, it can be left in place for the entire season.

The second strategy is to use Bt (Bacillus thuringiensis). This bacteria is harmless to humans but deadly to the larval (caterpillar) stage of many insects. It’s diluted in water and sprayed on affected plants. Floating row cover and Bt can be found at garden centers.

Aphids are also attracted to cabbage family crops. Floating row cover will keep them away from the plants, or you can knock the aphids off the plants with a strong jet of water from a hose.

Slugs seem to be my main nemesis. They typically chew holes in plant leaves, especially when those plants are young and tender. I’ve seen their damage on all types of seedlings. Slugs are primarily active at night and hide under boards and moist garden debris during the day.

You’d think they would be tropical critters and die out once our cold weather hits, but that’s not the case. I grow cold-tolerant vegetable crops through the winter months in a small hoop house and have seen them happily slithering around in there in January.

There are several organic slug baits on the market that are sprinkled around the plants. If you’re really desperate, beer is the answer, but it’s not for you. Slugs are attracted to the smell of the yeast in the beer, so use that to your advantage.

I sink empty tuna cans into the soil, with the top rim of the cans even with the soil surface. Then I pour cheap beer into the cans. The slugs are drawn to the aroma, fall in and drown.

Leaf miners are attracted to the leaves of spinach, Swiss chard and beets. The adult fly lays eggs on the leaves; when the larvae hatch, they quickly tunnel their way through the leaves. The easiest way to thwart them is by covering the crops with floating row cover throughout the season.

Stink bugs – specifically Brown Marmorated stink bugs – wreak a lot of havoc in gardens and orchards. They suck the juice out of tomatoes, leaving yellow marks on the skin, and they love artichokes, berries and tree fruits. So far, the only method I’ve found is to monitor the above crops regularly. If I find a stink bug causing damage, I hand-pick it and dispose of it in the trash. Scientists are researching control methods, so I’m hoping natural controls will soon be available.

Susan Mulvihill is co-author, with Pat Munts, of “Northwest Gardener’s Handbook.” Contact her at Susan@susansinthegarden.com.