Every year, I fill my garden boxes with fall crops, full of hope. Unfortunately, my boxes are full of slugs, and by January, I’m lucky if 50 percent of my plants have made it. The same thing happens in spring—aphids, squash bugs, cucumber beetles, and cabbage moths crawl out of the soil and begin their assault on my future crops. There are topical treatments and tricks, but the real answer is to go back in time to fall and take care of the problem before it starts.
At the end of the summer season, it is tempting to let things compost in place. But those plants are perfect hiding spots for bugs to slumber and lay eggs for spring. Compost them the proper way, in a compost pile that reaches temperature, so the bugs and any other viruses and fungi are mostly eliminated. Rotting fruit on the ground can attract vertebrate pests (in other words, cats, dogs, wild animals, and rodents).
If you’re like me, you’ve got row cover and trellises and tarps around from your gardening efforts all summer—it’s important to put these materials to bed correctly, too. They can also provide a cover for unwanted pests like cucumber beetle and squash bugs. Clean them, and then put them away rather than allow them to stay out in the yard.
Bugs—such as squash vine borers, cabbage moths, and cabbage loopers—can overwinter if they’re tucked in well enough. One solution is to bring out the rototiller and move your soil around. This should bring the pupae and chrysalis to the surface, exposing them to colder temperatures, which they’re less likely to survive.
Pests need cover, like grass, plants, and other hardscape hiding spots. If you remove those spots at the edge of the property, you give pests a more hostile environment, and they’re less likely to want to hop on over. This is particularly true for harlequin bugs and a number of brassica-loving pests.
If you’re putting in a winter crop, remember you still need to rotate beds so that you give crop-specific disease and pests less opportunity to settle in. But it’s not as simple as rotating the broccoli where the cauliflower was last year. You want to think in terms of entire crop families. Move the cabbage to where you had spinach last year, and the cauliflower and broccoli to where you had your winter beets and carrots.
Many people advocate leaving your leaves alone in fall, thus allowing good insects a place to chill until spring. If you do so, however, you provide cover to pests as well. Sometimes you have to sacrifice some good to prevent some bad, and you’ll need to weight the value in your own garden of making that choice. At any rate, if you chop any debris finely, it will compost sooner, giving less cover to bugs.
It's easy to say just skip the hard work and use a topical treatment like Sluggo or diatomaceous earth. As with all the other solutions, these have a cost and benefit. DE has limited effectiveness and must be reapplied frequently, and can hurt beneficial insects as well. Sluggo has to be reapplied often, and can create concentrations of iron phosphate in your soil, which can be absorbed by your vegetables. Now, I couldn't get by without Sluggo, and I try to limit its use, but I'm always sure to give my beds a good dose in fall.
