You Are Here: Management Updates 1998 Archive August 25, 1998

Date: August 25, 1998
Category: Diseases
Subject: Anthracnose, Dollar Spot, Slime Molds, Rust

Golf courses:
Anthracnose continues to plague many golf courses. This disease is common in hot, humid weather of August where turf is suffering from overplay and compaction at the end of summer. In many areas, roots are weak and poorly development. Core aeration is recommended regularly in spring and fall to help prevent the problem. Luckily, the disease is primarily foliar at this time, so fungicide applications will help in recovery. A DMI fungicide plus chlorothalonil are recommended. Avoid dragging the sticky spores by mowers and other equipment from diseased areas to unaffected areas.

Dollar spot is also rampant. This disease should respond well to a variety of fungicides in the absence of resistance problems. Avoid using the same chemical group repeatedly. The disease is more severe where turf is growing slowly due to drought and low nitrogen. It is also favored by long hours of moisture on leaf blades, so it is recommended to remove dew from fairways by mowing or whipping in the continuing humid weather.

Lawns:
The warm, humid weather will favor the return of slime molds on lawns and shredded bark. These saprophytes only eat dead organic matter and do not harm turf, but may appear suddenly and in startling quantity and colors that appear potentially harmful- bright yellow, beige, black/gray and powdery. Just rake or hose away. Drought is probably still the challenge in most areas. Slow growing grass due to lack of water or fertilizer plus the humid air favors the development of rust in late summer. Rust is easily diagnosed by the abundant orange, powdery spores produced on leaf blades. These rub off on the fingers and white shoes and socks. They are not harmful to animals or people. The best "cure" is to get the grass growing and mow it off before the spores can develop (which takes 10-14 days). Fungicides are helpful in severe conditions. The good news is that the spores will not survive the winter. Rust rarely kills turf plants.

- Submitted by: Dr. Gail Schumann