If there’s one thing you can count on in the autumn vegie patch, it’s caterpillars getting into your cabbage, broccoli, cauliflower and other brassica crops. Here are some ways to prevent what we call the ‘brassica massacre’.
Pick them off by hand
Every caterpillar removed by hand means one less adult to lay the eggs of the next generation. Check plants every couple of days while you’re out in the patch watering or weeding. They’re pretty good at hiding themselves and, being green, are easily camouflaged, so look thoroughly over each leaf, top and bottom. If you see caterpillar droppings or a freshly nibbled leaf, it means they’re close by. Pick and squash them, or toss them out for the chooks or other birds to feast on. Also, keep an eye out for pale yellow eggs, either single or in clusters, on the undersides of the leaves, and pick them off, too. That will prevent a lot of potential damage to your plants.
Net your plants
Covering your brassica crop with a pest-exclusion net, or even an old mosquito net, prevents the adult cabbage white butterfly from landing on the plants and laying its eggs. This makes it the easiest way, by far, to keep brassicas free from damage, but for it to be fail-safe, the plants must be covered from the outset. If you throw over a net midterm, be sure to thoroughly handpick pests or spray plants beforehand. ‘The nets are quite light, so they can be laid directly on plants, once established, without causing physical damage, or you can support them with a simple frame, such as electrical conduit held in place with short lengths of reo bar hammered into the ground.
Discover how to save your brassicas when caterpillar numbers are out of control, and ways to deal with other plant issues, including black spot on roses, in the March 2021 issue of ABC Gardening Australia magazine, out now.