Knowledgebase
Help identifying cause of spots on chilean guava plants #782827
Asked February 28, 2022, 4:17 PM EST
Hello,
A pair of chilean guava plants that I purchased as cuttings in early 2021 are showing some dark spots on their leaves. They are currently overwintering in my greenhouse, and I would like to make sure they don't have a disease or pathogen that could be spread to citrus or any other plants that I have growing in there as well. I have looked online, and while the most common cause for leaf spotting appears to be anthracnose, the pictures don't quite match. I first noticed these spots probably last fall as I brought them inside and they do not appear to have progressed or spread too much.
If this is a disease that may be communicable, what is the best way to handle it and reduce the chances that it will spread?
Multnomah County Oregon
Expert Response
Pictures failed to upload on first attempt.
Correction: These are two strawberry guava plants (Psidium cattleyanum), and not chilean guava, as originally stated.
Alternaria sp., Pseudocercospora psidii, Corynespora cassiicola and Phomopsis sp. The purplish spots on these leaves could be due to any of these or many other fungi. There appear to be wounds that started others. Hard to tell unless you send in a few sample to a plant disease clinic but I am not sure it is worth the $75 fee.
It appears these plants are evergreen and might react like a lot of other broad leaf evergreens in this climate. They are native to arid areas but get all sorts of spots in our wet climate. Once a new flush of leaves comes out they usually cast off the older leaves, especially if diseased like these. Have a look at madrone:
https://pnwhandbooks.org/plantdisease/host-disease/madrone-arbutus-menziesii-leaf-spots-blights
