15 Minutes of Fame for Leaf Spot

After looking back through prior alerts and posts, I discovered that leaf spot diseases have never made the cut, until now.  Recent weather patterns of cloudy and rainy weather across much of North Carolina have been perfect for foliar diseases such as Bipolaris leaf spot and gray leaf spot.

Bipolaris Leaf Spot on Bermudagrass

We have received several samples of bermudagrass in the past week that were devastated by the fungus Bipolaris cynodontis. Bipolaris leaf spot is most severe on turf that is growing slowly due to adverse weather conditions or improper management practices.  Shaded areas with little or no air movement result in weak turf and extended periods of leaf wetness that favor disease development. Deficient or excessive nitrogen, excessive thatch, extended periods of leaf wetness, drought stress, and low mowing heights are factors that encourage the development of leaf spot diseases.  These fungi may spread to the crowns and roots and cause melting out, which is most severe during periods of hot weather.  For more information about leaf spot, including control recommendations, click here.

Gray Leaf Spot on St. Augustinegrass

We have also received several samples of gray leaf spot on St. Augustinegrass here at the NC State TDL. Proper mowing practices are most important for gray leaf spot management in St. Augustinegrass. This grass must be mowed frequently during the summer months to remove excess leaf tissue, keep the canopy open and dry, and remove developing gray leaf spot lesions. Collecting clippings reduces spread of the disease when gray leaf spot symptoms are evident. Apply nitrogen and other nutrients as recommended to maintain vigorous foliar growth during the summer months. Excessive shade, in addition to promoting leaf wetness, slows St. Augustinegrass growth and enhances gray leaf spot problems. For more information about leaf spot, including control recommendations, click here.