June 10, 2013
Conditions have been very wet in the Midwest this spring, which has resulted in a very fast growth rate of turf. Most of us are having a hard time keeping up with mowing. These wet conditions in spring are often followed by a leaf spot breakout in turf. The picture below is from the Chicago area. It shows the typical leaf spot symptoms on fairway bent.
Symptoms generally include blighting from the tip down on bent, rather than the standard leaf spot lesions seen on other species. The turf on the area may also look like it is dry, even if the soil is wet. The grass also takes on a brown "haze" when you look at it from a distance.
The fungi that causes this is usually attributed to Bipolaris or Dreschslera (formerly Helminthosporium), depending on the author. I will let the pathologist sort that one out.
Chlorthalonil (Daconil and other commercial names) is the standard answer for this problem, although there are several fungicides labeled for this disease.
This disease can also hit greens, but most golf courses are treating greens and it is not as common as it once was. Because of the cost, fewer superintendents are treating fairways and that is where we are seeing most of the problem this spring.