You Are Here: Management Updates 1999 Archive August 9, 1999

Date: August 9, 1999
Category: Diseases
Subject: Summer Diseases

Cool nights are reducing turf stress in some areas of New England, but high night temperatures remain in southern areas. Over the hot, humid weekend, PYTHIUM BLIGHT, BROWN PATCH and other hot weather diseases were common even in lawns. These have been eliminated where night temperatures are cooler night temperatures, but the lack of rain remains a problem.

ANTHRACNOSE has been diagnosed in compacted, high traffic areas such as clean-up passes in both bentgrass and Poa annua on putting greens. Many remaining Poa annua plants appear to be infected with BACTERIAL WILT for which there is no treatment. Some superintendents have used contact copper sprays such as Kocide or Junction to try to reduce further infections. SUMMER PATCH and PYTHIUM ROOT ROT are also common in declining Poa annua plants. Where turf is in poor condition, it is probably best to concentrate on good agronomy rather than fungicides- aeration, overseeding, renovation.

GRAY LEAF SPOT of perennial ryegrass has still NOT been confirmed in any areas including Kentucky. Please submit any suspicious samples to a diagnostic lab, so we can confirm the problem and warn turf managers. I will post any confirmations here as soon as possible.

NEMATODE analyses continue to show very high numbers on a number of golf courses. Symptoms of apparent nematode damage have been observed on the roots themselves which is not a common phenomenon in New England. Nematode numbers may not drop quickly even after a nematicide application. We are quickly approaching the time in the season when such applications are no longer recommended because numbers drop naturally. Where roots are limited, populations also drop because nematodes require healthy roots for feeding.

Several samples of bentgrass with yellow, dollar-spot sized spots have been observed. The roots and leaves do not appear to be infected by a pathogen, and symptoms remain relatively unchanged for several weeks. A micro-climate nutrient deficiency is suspected.

- Submitted by: Dr. Gail Schumann