You Are Here: Management Updates 1998 Archive September 23, 1998

Date: September 23, 1998
Category: Diseases
Subject: Turf Disease Special Alert - Gray Leaf Spot

The first sample (ever) of GRAY LEAF SPOT (Pyricularia grisea) has arrived at the UMass Turf Disease Diagnostic Lab from a golf course in Connecticut. This destructive new disease attacks ONLY PERENNIAL RYEGRASS AND TALL FESCUE. It caused massive fairway losses in the mid-Atlantic states a few years ago and has been moving northward and westward with minor outbreaks since then. It seems to be triggered by long periods of drought and heat stress as we have been experiencing. It often begins in overseeded perennial ryegrass and then moves into established plants. Lawn care managers should be on the alert for the problem in perennial ryegrass and tall fescue lawns.

The symptoms are gray leaf spots, as the disease name suggests, but the leaves will rapidly wither and die. In humid conditions, you may be able to see the fuzzy growth of the abundant spores of the fungus. Under a microscope, they are very distinctive- pear shaped with 2 septa or cross walls.

Other problems in the past week on golf courses include continuing foliar anthracnose and the basal rot stage, mostly on Poa annua. Take-all patch has been seen on relatively young plantings (1-3 yrs old)of bentgrass. Rust is very common in lawns because of the drought. See last week's message for further information. The rain and cooler weather should return us to more typical conditions and help turf recover from the past weeks of stressful weather. Be on the alert for red thread if cool, wet weather settles in on the drought-stressed turf.

- Submitted by: Dr. Gail Schumann