It happens every year. I forget the gardening lessons of the year before. Take my many failed attempts to grow cabbage, for instance. It always gets decimated by the imported cabbage worm (Pieris rapae), a creature as abundant in Los Angeles as aspiring actors.
There are several strategies I could use to deal with this pest (cabbage worms, that is–I have no problem with actors). I could spray Bacillus thuringiensis but I don’t like the idea of killing non-target species, not to mention the disputed human health effects of BT. I could use row cover, but this winter has been way too warm for even the thinnest material.
The best suggestion comes from the University of Florida. Find resistant alternatives:
Crucifer crops differ is their susceptibility to attack by imported cabbageworm. Chinese cabbage, turnip, mustard, rutabaga, and kale are less preferred than cabbage, collards, Brussels sprouts, broccoli, and cauliflower. Some cultivars of certain crops also have moderate levels of resistance to infestation by imported cabbageworm. One resistance character is due to, or correlated with, dark green, glossy leaves. This character imparts resistance to imported cabbageworm and other caterpillars, but increases susceptibility to flea beetle injury (Dickson and Eckenrode 1980).
I’ve noticed that the huge Franchi “kale” (collard?) that has gone into its second year, seems to be less popular with the cabbage worm than the adjoining Portuguese cabbage. Next year, I’ll skip the cabbage and plant something else. I like mustard better anyways. If I want cabbage I can outsource the growing and pick it up at the farmers market.
Have you had problems with cabbage worms? How have you dealt with it?