Diseased kale plants - Ask Extension
Hi! I just got back from a trip and my kale plants look like this. I got some cast-off starts from a local nursery so I don't know the plant starts' ...
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Diseased kale plants #879293
Asked July 29, 2024, 4:05 PM EDT
Hi! I just got back from a trip and my kale plants look like this. I got some cast-off starts from a local nursery so I don't know the plant starts' history, but it looks like some sort of insect got them (no trace of snail trails).
Any advice on what kind of pest is the problem and how to deal with it?
(Note: yes, I know the kale plants are far too close together in this pot, and that might be contributing to the problem. I just temporarily placed them here and intend to transplant each into its own pot once I get a bit more potting soil. But I don't want to transplant them if they're severely distressed from insect damage!)
Boulder County Colorado
Expert Response
Hi Josie,
Sorry to hear about your kale challenges. Unfortunately, lots of pests love to munch on our kale. What I'm seeing is it appears the leaves on the plant close to the top of the photo have been completely chewed off. This makes it hard to identify exactly what caused this but likely culprits are: cabbage worms, grasshoppers or rabbits. If you check the leaves, do you see any green catepillars on these plants? They can be quite small. Here's a resource showing some pictures: https://agsci.colostate.edu/agbio/ipm-pests/32035-2/
Additionally, there are a few leaves (one at the bottom of the photo and one on the righthand side) that show signs of leafminers (there are white lines throughout the leaves of the plant). I would recommend cutting off and destroying those leaves as they will continue to reproduce on there. It would also be a good idea to check all other leaves for signs of eggs - usually these are found on the underside of the leaves.
Here is a resource on leafminers with some pictures highlighting what their damage looks like: https://extension.colostate.edu/topic-areas/insects/leafmining-insects-5-548/
It might be a good idea to protect these plants in some way from further pest damage while they're so small. What can be helpful in this regard is spraying with insecticidal soap to kill off any soft body insects, ensure there's no grasshoppers in pot and then covering the whole thing with insect netting. Most garden centers will have netting that can exclude insects and you can use any flat-topped stake to prop the netting over the top of the plant so that it isn't touching the leaves (otherwise small bugs can chew and lay eggs through it). Alternatively, if you have space, you can do the same steps but instead of using insect netting just bring the pot indoors for a bit and place it in a sunny window in your house. Once the plants have grown a bit more and have more leaves, they will be good to go back outside, though they will need to continue to be monitored for pests throughout the season.
Here is a resource giving more information on insecticidal soaps: https://extension.colostate.edu/topic-areas/insects/insect-control-soaps-and-detergents-5-547/
Please let us know if you have any additional questions!
Best wishes,
The Boulder County Extension Master Gardeners
Sorry to hear about your kale challenges. Unfortunately, lots of pests love to munch on our kale. What I'm seeing is it appears the leaves on the plant close to the top of the photo have been completely chewed off. This makes it hard to identify exactly what caused this but likely culprits are: cabbage worms, grasshoppers or rabbits. If you check the leaves, do you see any green catepillars on these plants? They can be quite small. Here's a resource showing some pictures: https://agsci.colostate.edu/agbio/ipm-pests/32035-2/
Additionally, there are a few leaves (one at the bottom of the photo and one on the righthand side) that show signs of leafminers (there are white lines throughout the leaves of the plant). I would recommend cutting off and destroying those leaves as they will continue to reproduce on there. It would also be a good idea to check all other leaves for signs of eggs - usually these are found on the underside of the leaves.
Here is a resource on leafminers with some pictures highlighting what their damage looks like: https://extension.colostate.edu/topic-areas/insects/leafmining-insects-5-548/
It might be a good idea to protect these plants in some way from further pest damage while they're so small. What can be helpful in this regard is spraying with insecticidal soap to kill off any soft body insects, ensure there's no grasshoppers in pot and then covering the whole thing with insect netting. Most garden centers will have netting that can exclude insects and you can use any flat-topped stake to prop the netting over the top of the plant so that it isn't touching the leaves (otherwise small bugs can chew and lay eggs through it). Alternatively, if you have space, you can do the same steps but instead of using insect netting just bring the pot indoors for a bit and place it in a sunny window in your house. Once the plants have grown a bit more and have more leaves, they will be good to go back outside, though they will need to continue to be monitored for pests throughout the season.
Here is a resource giving more information on insecticidal soaps: https://extension.colostate.edu/topic-areas/insects/insect-control-soaps-and-detergents-5-547/
Please let us know if you have any additional questions!
Best wishes,
The Boulder County Extension Master Gardeners
