Turfgrass Disease and Stress Update

Dr. J.M. Vargas, Jr.

Michigan State University

Well summer has finally arrived with a vengeance! Up until now other than some dollar spot and Waitea patch it has been a dull summer for diseases. Now with the arrival of the warm weather brown patch, Pythium blight, crown rot anthracnose, foliar anthracnose and summer patch are all becoming a problem. The real key to the development of these diseases has been the warm night time temperatures. These diseases become problems when the night time temperatures stay above 68 F. Of course the humidity has also helped these diseases to become a problem.  It is important to remember where these diseases are occurring the fungus is already inside the plant and it is necessary to use a systemic fungicide to stop the advance of the fungus inside the plant.  Contacts fungicide may prevent any new infection but they will do nothing to prevent the fungus in the plant from causing further damage.  Many areas in the state have received a lot of rain this spring and summer and consequently the turf has poorly developed root systems from oxygen continually being pushed out of the root zone.  The reason for mentioning this is soon the cooler weather will return and with it will be cool days in the 70’s with low humidity.  On these days, and especially if the wind is blowing the turf will begin to wilt rapidly and die if irrigation is not applied quickly. So in other words, don’t relax and let your guard down just because cooler weather has returned.

Brown patch on a putting green.