Knowledgebase
Lesions/rot on pepper leaves #878326
Asked July 22, 2024, 5:43 PM EDT
I have six pepper plants, and one of the six is clearly unhappy compared to all the others. The leaves are developing dark, rotting lesions, then falling off without fully yellowing. What is this? Is it something I can hope to save the plant from, or should I pull it ASAP so the disease doesn't spread?
In the photo of the two plants, the one on the left is the affected one—note how many of the lower leaves are gone, and I removed a number of diseased leaves higher up as well. I took more photos than I can attach here, so I put them in a Google Photos album.
Washtenaw County Michigan
Expert Response
Hi Daniel, thanks for the question.
This appears to be a bacterial infection. Most likely bacterial leaf spot caused by the bacteria Xanthomonas campestrispv. vesicatoria. This disease can be seed borne. It can be spread by rain from infected plant debris to healthy leaves. It can also come from infected transplants. This pathogen can overwinter. The most effective mode of action would be to remove and destroy the infected plant and spray a copper fungicide as a preventative on the other plants. Check out the following links for more information:
Bacterial Leaf Spot of Pepper | Extension | West Virginia University (wvu.edu)
Bacterial Spot of Pepper and Tomato | NC State Extension Publications (ncsu.edu)
I hope this is helpful.
Looks like I'm probably going to lose both of the pair of plants in the picture, but I have others planted further away that seem unaffected. I decided not to bother with the fungicide just to try to save the one neighboring plant, but I am curious for the future—why is a fungicide effective here for a bacterial infection? I'm guessing there must be a fungus that "opens the door" so to speak without being as problematic on its own, and controlling that limits the ability of the bacteria to gain a foothold?
Hi Daniel,
Copper is both fungicide and bactericide. When used as a preventative it has the ability to limit both bacterial and fungal infections.
