 Plant Edema
Well, we do learn something new every day! Last week a customer came in with a leaf from her ligustrum tree with some unfamiliar symptoms of raised, splotchy areas. Our first guess was some kind of a fungus, but we weren't certain, so Steve asked the customer to take some close up pictures, and he forwarded them on to Dr. Tim Schubert, Plant Pathologist with the Division of Plant Industry for the State of Florida. He sent us this very helpful reply: "Your pictures suggest a physiological problem called edema, nothing to do with a fungus. Some information about the disorder can be found here. "The cause is excess water retention in the tissues which results in bumps and patches of exploded cells on leaves that eventually crust over into brown tissue such as you see here. Usually the exploded cells are in the form of bumps such as those in image 7228. The larger patches are unusual, but not unprecedented. The lesions are most common on the underside of foliage. Certain plants are especially prone to this disorder, and ligustrum is one of them. Sometimes, pesticide applications, even mild ones like insecticidal soap or horticultural oil, can damage young tissues to cause similar patches of crusted epidermal tissues. Pesticides applied in the summer heat can be especially problematic. You mention no pesticide application here, but the onset of abundant rains seems to correspond nicely to the appearance of the lesions. If the irrigation system in a managed landscape such as the Villages continued to apply water through the storms, that would make the problem even worse. Eventually, you could expect root rot problems from the soggy soils. "I predict this problem to remain stable and not get worse as long as edema-conducive conditions do not prevail. If it stays very wet, you could see more of this. " So, a reminder for the rest of the summer rainy season: Be sure to adjust your irrigation according to the amount of rainfall we are getting. Too much of a good thing really can be bad. |
