Dollar Spot Runs Rampant

Dr. Joe Vargas, Jr.
Michigan State University

In the last couple weeks it seems dollar spot has been everywhere from golf course fairways, tees, and roughs to athletic fields and home lawns.  Conditions have been perfect for the development of dollar spot with several days when dew did not dissipate into the early afternoon. Normally dollar spot occurs in August and September in Michigan, but because of the cooler than normal summer it has been a problem since back in May. It has been especially active the past couple of weeks.  Once it gets started it is difficult to control. It is important to remember where the disease is active 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. The dollar spot fungus has become resistant to many classes of fungicides including thiophanate-methyl, iprodione, vinclozolin, and the DMI chemistry.   So keep this in mind when you are trying to managing dollar spot.

Dollar spot active in turf.