Will SDS appear sooner this year?

Over the holiday season I often take a look at weather predictions for the coming year. I do this for a couple of reasons, one, to see how long winter is going to last and two, to get an idea of when turfgrass pests can be expected to show. The predicted severity of the winter can help determine whether the pest season will start earlier or later than normal.

There are several complicated and technically accurate weather forecasting systems, but I tend to stay with the one I have used prior to the digital age, the Farmer’s Almanac. The winter weather forecast for 2021 from the Farmer’s Almanac states in part:

“If you were hoping for a reprieve from harsh winter weather this year, we have some news that just might make you smile. We’re predicting a light winter for most of us here in the United States, with warmer-than-normal temperatures in the forecast for a large part of the country.”

Figure 1.  Spring dead spot (SDS) is a devastating disease that can linger through the summer. In the above photograph, the early spring symptoms of SDS have lingered through the summer in North Carolina.

The good news is maybe the winter isn’t going to be too bad and spring will arrive early. This may be a mixed bag of both good and bad with regard to spring dead spot (SDS). On the good side, the severity of SDS may be low due to the lack of cold or freeze injury that could enhance infected bermudagrass. On the other side,the likelihood of spring dead spot symptoms becoming apparent sooner in bermudagrass grown areas is high.

Root pathogens that are the causal agents of spring dead spot infect bermudagrass roots through the fall and winter. Often times infection occurs in the same area year after year.  The circular dead areas occur when the infected area collapses.  Recovery of these dead areas requires the surrounding bermudagrass to colonize and re-establish in the damaged areas often requiring most of the summer.

Figure 2.  Early spring symptoms of spring dead spot.

Cultural practices to reduce the severity of SDS include fall applications of potassium to reduce SDS by enhancing the cold tolerance of Bermudagrass.  Lowering the soil pH on alkaline soils reduces the severity of SDS spending on the pathogen.  Both Ophiosphaerella korrea and O. hepotricha can cause SDS in the United States. Ophiosphaerella korrea is more responsive to treatments lowering soil pH than O. hepotricha.  

Chemical control of SDS during the spring is ineffective. Areas that show SDS should be noted or mapped and treated in the fall.  Fungicides recommended for SDS control include Posterity^® Forte, Velista^®, and Headway^®.  Following application, apply immediately at least a ¼ inch of irrigation. 

Figure 3.  Spring dead spot occurs globally on Bermudagrass turf. 

And to sign up for spring dead spot alerts, visit GreenCastOnline.com/AgronomicAlerts.

About the author

Dr. Karl Danneberger is a professor of Turfgrass Science at The Ohio State University. Dr. Danneberger's contact information can be found here. You may also follow Dr. Danneberger on Twitter: @GlobalTurf