Plant Diseases/leaf narrowing on Rose of Sharon; necrotic tissue on ornamental pear
QUESTION: Dear Dr. Vann,
I work at a nursery; a customer brought in some leaves for me to take a look at.
Rose of Sharon: the shrub in question is mature and has been healthy over its lifetime. The customer presented me with a twig from the lower half of the plant. The leaves are reduced, narrowed, and in some cases cupped. There are no visible cankers, insects/mites, or signs of fungal infection. There is no history of glyphosate application. Could it be viral? Phytoplasma? I can't find a whole lot of information regarding disease in rose of sharon! Apparently the entire lower half of the shrub is affected; the foliage on the upper part of the plant is normal.
Ornamental pear: No idea what the variety is. The midvein on the leaves is necrotic, with necrotic tissue spreading out from the midvein. Looks almost like Erwinia - but there are leaf spots too on the rest of the leaf tissue. The lesions are very dark, mostly circular, with a rust-colored center; no evidence of fruiting bodies or oozing, at least using a hand lens. The distribution of diseased leaves is generalized and the trees have been in the ground for two years.
Any thoughts? Thank you so much for your time!
The symptoms that you describe on the ROS does not sound like an infectious/contagious type of problem. Eventhough you mentioned no glyphosate involvement, I would be suspicious of a contact/uptake issue from your description. I would look into the history of ANY chemical applications (such as any other herbicides) made under the shrub or nearby. Some growth regulator types of herbicides can cause these type symptoms. Also, any nearby plants with similar symptoms?
Not sure about the Callery pear. Any chance you could send me a couple of closeup images of representative symptomatic foliage? Be sure your image is in focus by reviewing it on the computer before sending. Can you describe the distribution of the leaf problem on the tree? Also, is it getting worse (spreading)?
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QUESTION: Thank you for your prompt response - I really appreciate it!
The customer claims no chemical application of any kind under or near the ROS, though I certainly agree with your assessment. There aren't any nearby plants with similar symptoms.
I could probably get ahold of some new leaves when I call the customer back. I will take some photos of what I have, but they may be too dessicated at this point to be very useful. If I get any good shots, I will send them along. As to the distribution of symptoms - she says it's generalized throughout the canopy of the tree. I'll ask her if she thinks it's spreading.
Thank you again for your response - I so appreciate it!
Thanks Anne. A photo or two can be useful. Get the customer to monitor the condition to see if it is getting worse. This may be a temporary stress. If you can send a photo, make sure to select and photograph a group of 3-5 leaves with representative symptoms that are being seen.