You Are Here: Management Updates 1998 Archive June 30, 1998

Date: June 30, 1998
Category: Diseases
Subject: Dollar Spot, Brown Patch, Anthracnose, Fairy Ring, Slime Mold, Red Thread

Last week's flirtation with warmer weather resulted in tremendous outbreaks of DOLLAR SPOT especially where fertility was low following excessive rainfall. BROWN PATCH was also prominent in many areas. This disease can be confusing in such wet weather because the fungus may look white when growing quickly and abundantly. In addition, brown patch can be active in relatively cool weather as long as night temperatures remain above 59 F. It apparently did not get hot enough for PYTHIUM BLIGHT this time, but the very wet conditions are certainly prime for it if the weather suddenly becomes hot. A recent weather report suggests that a Central Canadian front may be headed our way for the first part of July which would be a welcome change.

ANTHRACNOSE is still common on many golf courses. It is most common in traffic areas, compacted areas, thatchy areas, where mowing height is too low, and where N is low. A number of golf courses are noticing FAIRY RING. This is the only disease that causes extra green color development in rings, arcs, etc. There may or may not be mushrooms or other fruiting structures (birdsnest fungi, puffballs). There may or may not be yellowing or browning of turf to the inside or outside of the greener rings. Fairy rings are often associated with excess thatch, so reduction of thatch is the most useful approach to control. Try spiking, light topdressing, wetting agents. Only ProStar has a label for fairy ring and results have been very mixed. It may be easier to mask the symptoms with iron and light fertilizer applications. Many times the superintendents notice the problem more than the golfers. Fairy rings are of little concern in lawns.

Another curiosity that commonly shows up with warm, wet weather is SLIME MOLD. This is not a true fungus, but shows up suddenly and sometimes in great abundance. Many people are familiar with the bright yellow slime molds on bark mulches that mature to a beige color and black powdery spores. On turf, they generally appear slimy black in small areas and mature to light gray and black powdery spores similar to cigarette ashes. A quick diagnostic test for a slime mold is that it will be found on grass blades as well as any clover or other weeds in the area. The good news is that slime molds are saprophytes and eat only dead organic matter. They do not cause injury to turf unless they are very thick like a blanket. Hose or rake them away. RED THREAD persists in lawns with the continuing rainy weather.

- Submitted by: Dr. Gail Schumann