Microdochium patch requires more fungicide applications in the Pacific Northwest than other diseases. Frequent fungicide applications are costly and could lead to fungicide resistance. Also, potential pesticide restrictions are cause to find methods that reduce fungicide applications.
Oregon State University researchers investigated if sulfur and calcium applications reduce fungicide use by monitoring the number of fungicide applications to manage Microdochium patch on an annual bluegrass putting green.
The control plot required 4.1 fungicide applications over an eight month period. Plots treated with 3 or 6 pounds of sulfur per 1,000 square feet required fewer fungicide applications (Table 1). The reduction in the number of infection centers was small and not significant.
Three pounds of sulfur per 1,000 square feet slightly reduced turf color ratings compared to the control. The 6-pound annual rate of sulfur was the same as the control (Table 1). Percent anthracnose disease was higher in August for the medium and high rates of sulfur. There were no differences in anthracnose disease from the calcium products.
Results from the study provide the following conclusions:
- Sulfur applications slightly reduced Microdochium patch on an annual bluegrass putting green.
- Applied sulfur reduced fungicide applications using infection centers as an action threshold.
- Sulfur applications increased Anthracnose activity when summer fungicides were not applied.