Turf disease such as pythium, anthracnose and dollar spot affect highly managed turf during the hot and humid summer months. This July has been no exception as the humidity has been very high all month. Dollar spot is the most prevalent disease on our cool season grasses here at the course. The pathogen that causes this disease can grow when temperatures are between 50-90 degrees but is most probable when temperatures are between 70-80 degrees. Dollar spot, as well as most turf diseases, thrive in wet conditions. Prolonged leaf wetness, most commonly from mornings with heavy dew, cause the disease to develop and spread through the turf.
 |
| Dollar spot (Clarireedia jacksonii) |
 |
| Dollar spot with visible mycelium |
On closely mowed turf, dollar spot injury is generally 1-3 inches in diameter and are often sunken. On higher mowed turf, they may be as much as 6 inches. Where disease is bad these spots can merge into large areas like in the top picture on this post. In the second picture the growth of fungal mycelium is visible.
 |
| Close up of mycelium on leaf blade |
This mycelium can be transferred from one plant to another from mowing and foot traffic. Left untreated it has the potential to take over and kill a lot of turf but fortunately it is a relatively slow grower and can be both prevented and/or treated reactively after development. The best way to combat turf diseases is having a healthy stand of grass. Low nitrogen fertilizers with micro-nutrients are spoon fed to the greens throughout the stressful summer months. This July we applied two applications of preventative fungicides to the greens that cover a broad spectrum of turf diseases which include dollar spot.
