They’re coming. In fact, they’re already here. The seemingly beautiful white butterflies that hover delicately over your kale plants might appear to be innocent, but in reality they can wreak havoc on your brassicas if left unchecked.
They’ll flutter around looking for a nice place to land, then disappear underneath the leaves of your treasured broccoli and cabbages. When they emerge, they will have laid dozens of eggs on the underside of the leaves that are so tiny they are almost invisible to the human eye. Almost, but not to the trained human eye. What to look for? Tiny bright green dots.
Thumb added for perspective. Elongated bright green egg attached to underside of leaf.
When that egg hatches, out comes a ravenous worm, also very small and hard to see:
Same thumb, different worm – already eating at such a young age.
Those worms grow larger, eating their way through your plants, to become the green worm we know and despise.
Courtesy of Purdue University
Okay, so how do we combat them?
Prevention – The easiest way is to prevent them from every reaching your plants in the first place. Use Floating Row Cover or garden fabric to cover your plants while you see butterflies in your garden. Then remove the cover after the threat has passed, and enjoy your greens intact.
Kale covered with floating row cover
Hands-on – If you have a small patch of brassicas, a daily walk through the garden will help keep them at bay. Turn over the leaves and inspect them for eggs and tiny worms. Wipe them off with your fingers and remove and destroy larger worms.
Drastic Measures – If you have a larger area or don’t want to squish by hand, you can use this pyrethrin-based spray that will kill cabbage worms and other pests.
In the end, only a severe infestation will destroy your plants completely, so if you can stick to hand picking and tolerate the rest, all the better.