You Are Here: Management Updates 2003 Archive June 25, 2003

Date: June 25, 2003
Category: Diseases
Subject: Pythium, Brown Patch, Slime Molds, Red Leaf Spot

Pythium blight doesn't happen as often as people think, but check your local forecast for night temperatures of 68° F and up. Greens and tees should be protected with a Pythium fungicide because of the potential for severe damage due to frequent mowing. This recommendation is based on the very high moisture content of soils throughout the area. In lawns and fairways, you may want to simply watch for the little greasy to reddish spots that may appear first and consider spot treatments. In these areas, waiting until the turf is dry before mowing will minimize damage. Luckily, a good break in the weather is just a couple of days off. If you decide to spray, be sure to tank mix with a fungicide for brown patch which is the more likely problem this week. Keep in mind that the Rhizoctonia fungus that causes brown patch can look whitish rather than the typical "smoke ring" color when it is growing quickly in wet conditions. Late afternoon and evening thunderstorms will wet things down for the night and increase disease danger. Do not irrigate in the afternoon and night in this hot weather (except for syringing of greens). Water in the early morning hours.

Slime molds are active at this time. Look for large fungal-like growths that appear in wet grass quite suddenly, i.e. overnight. They do not hurt turf and can be mowed or washed away. They start out slimy but mature into powdery masses of spores.

Red leaf spot (Drechslera erythrospila) is a leaf spot of bentgrass and is active at this time. It causes a reddish cast to the leaves. Luckily, there are many standard fungicides which will bring this disease under control. Avoid nitrogen applications until the hot weather is over and diseases are checked.

- Submitted by: Dr. Gail Schumann