You Are Here: Management Updates 1999 Archive July 16, 1999

Date: July 16, 1999
Category: Diseases
Subject: Environmental Stress, Take-All Patch, Anthracnose, Bacterial Wilt

Residual effects of the recent ENVIRONMENTAL STRESS conditions continue to dominate the turf complaints. In many areas, both bentgrass and Poa annua are slowly recovering, but problems with Poa annua are more common. Many of the samples do not contain evidence of an obvious fungal pathogen. NEMATODE numbers in many of the samples are extremely high. The only chemical control for nematodes is Nemacur which is highly toxic. If turf appears to be recovering, this may be evidence that the turf is capable of tolerating the nematode populations.

In young bentgrass, TAKE-ALL PATCH continues to be a problem especially where pH levels are high. ANTHRACNOSE has rapidly developed on some courses and has progressed to the basal rot (crown rot) stage. We continue to recommend a DMI fungicide (Banner, Bayleton, Eagle) or Heritage plus chlorothalonil (Daconil, Echo, Manicure, etc.). The combination of the systemic plus chlorothalonil is most effective.You may continue to observe the black hair-like setae of the fungus even after treatment, but the sticky masses of spores among the setae should be less evident. Plants with basal rot will recover slowly, if at all.

BACTERIAL WILT is a controversial disease problem in Poa annua. It is seen in Poa plants that have been severely stressed. This year it seems to be occurring in Poa that recovered from last winter's ice damage and then was subjected to the early June heat, several weeks of drought, and the 4th of July weekend misery. It is my opinion that this is a secondary problem found in Poa that is probably already doomed. Superintendents have observed that Poa plants that were not ice-damaged are often doing well in the same green and that one green may be affected and a nearby one not. This suggests that only very badly weakened Poa plants are developing bacterial wilt. The bacteria are found in the xylem (vascular tissue), so there are no available chemicals that can cure the infected plants.

There are still NO confirmed reports of GRAY LEAF SPOT on perennial ryegrass in Kentucky, New Jersey, Maryland, New Jersey, Pennsylvania, or New England.

- Submitted by: Dr. Gail Schumann