Knowledgebase

Brussel Sprout and Kale Pest? #772551

Asked September 21, 2021, 2:25 PM EDT

Something has devastated my fall crop of brussel sprouts and kale. The leaves have nothing left but the veins. There are also dark pieces in the stem area (worm droppings? mites?). Please see attached pics. I did see a few worms that were white w/ a yellow-green stripe. Any idea what this is and how to treat it?

Sussex County Delaware

Expert Response

Good morning,

I'm sorry to say your kale has been the victim of an intense cabbage white attack. Cabbage whites, or imported cabbageworms, are one of 4 very common worm pests that are extremely destructive of all brassicas - kale, collards, cabbage, broccoli, brussels sprouts, cauliflower etc. The other common worms are cabbage looper, diamondback moth, and cross-striped cabbageworm. 


In the first photo i see the green fuzzy worms on the midveins. The adult is a white butterfly that lays single cone shaped yellow eggs on the undersides of leaves. The black spots are worm droppings. 

The good news is these are easy to control with insecticides. For commercial ag, you can find our recommendations for brassica pests at https://www.udel.edu/content/dam/udelImages/canr/photography/extension/sustainable-ag/NFP-2020-F-Cole-Crops.pdf. For a home garden plot, your best options include liquid Sevin (zeta cypermethrin), Bonide's Captain Jacks Dead Bug (spinosad), and B.t. if you have small worms. These worms are pretty large, so the first two options are best. Spinosad does not hurt non-caterpillar and thrips insects (fairly safe to handle, does not hurt pollinators, and is an organic insecticide), but it works very well on caterpillars. Liquid Sevin was reformulated a few years ago to include zeta cypermethrin, this is a broad spectrum insecticide that will kill cabbage whites, cabbage loopers and cross striped worms, but not diamondbacks. It will also control harlequin bugs which are orange and black stink bugs that can be devastating on brassicas (my kale was killed earlier this summer from them). 

Hope that helps. Best of luck! I hope the kale releaf's.


Sincerely,

David Owens

UD ag extension entomologist

<personal data hidden>

An Ask Extension Expert Replied September 22, 2021, 10:16 AM EDT

Loading ...