Following recent periods of wet, cloudy weather we've had several reports of a disease appearing on bermudagrass putting greens. The symptoms are a rapid foliar blight that initially has a purple coloration but then fades to tan. Spread on mowers or in drainage patterns usually occurs as well. Many superintendents assume that this is leaf spot, which of course is a common bermudagrass disease during wet weather in the fall. I have to admit that the first time I saw this I also thought it was leaf spot. But I was wrong - it is Pythium blight.
Pythium blight in October? Yes, you read it correctly, it is Pythium blight in October.
There are a lot of Pythium species that can infect grasses. Most people are familiar with P. aphanidermatum that causes Pythium blight on the cool season grasses during hot summer weather. However, there are other Pythium species that grow during cool or cold weather. We don't know what species is causing this outbreak yet, but obviously it grows well during cool weather and has a competitive advantage over the bermudagrass under these conditions.
Fungicide treatments may not always be necessary to control Pythium blight on bermudagrass, as dry and sunny weather usually put a stop to it very quickly. However, if the forecast is calling for extended periods of wet and cloudy weather, an application might be a good idea. Any strong Pythium fungicide should do a good job.
