What causes holes in Brussels sprout leaves?

QUESTION: I can’t determine what is eating my Brussels sprouts. What causes holes in Brussels sprout leaves? What is the black stuff in Brussels sprouts? – Tiffany R

ANSWER: Small, irregular shaped holes in Brussels sprout leaves are signs of the presence of army worms or cabbage loopers, both of which are small green caterpillars. Army worms are dark green and cabbage loopers are dark green with yellow stripes down their backs.

Tiny shot-holes in the leaves of Brussels sprout seedlings are the work of flea beetles, which feed on the roots of germinating plants. There are several ways to treat and prevent flea beetles, such as spreading diatomaceous earth around your seedlings, handpicking off plants, and cultivating often to disrupt life cycle. Keep your garden clean, spade the garden soil deeply to destroy larvae in early spring, or treat plants with Sevin, pyrethrum, or rotenone to prevent flea beetle infestations.

What is the black stuff in Brussels sprouts?

Small, black, granular matter is occasionally found in the interior of Brussels sprout heads. The black stuff is most likely detritus, or the droppings left behind by insects, namely aphids and caterpillars. Aphids can be blasted off of your plants with jets of water sprayed from a water hose. Plants can also be treated with an insecticidal soap spray to deter burrowing pests that like to inhabit sprout heads.