We are seeing bacterial or angular blight again in cotton. I have a dryland variety trial I looked at this morning and it is showing up in different varieties. Unfortunately, we cannot do anything we can spray. We can irrigate during the night to reduce leaf wetness. Our trail was planted in late May, so we are being everything else. Cotton is not yet too rank. I’m not seeing but a few leaves here and there, but every leaf I find has already dropped from the plant. It is too early to know how much this will impact us. Here is more information from UGA Extension Pathologist Dr. Bob Kemerait:
Once again, we are finding bacterial blight, caused by Xanthomonas citri pv malvacearum, in cotton in Georgia. The disease can be diagnosed by presence of water-soaked-to-necrotic spots on the leaves that are delimited by the veins of the leaf. This gives the spots a particular “angular” appearance. The disease can also spread in the veins and gives a “lightning bolt” streak on the leaf. Crater-like, water soaked lesions can form on bolls.
There is nothing that can be done to manage this disease. Managing growth of the crop and irrigating at night to reduce leaf wetness periods can help a little.