You Are Here: Management Updates 2003 Archive July 11, 2003

Date: July 11, 2003
Category: Diseases
Subject: Take-All, Summer Patch, Necrotic Ring Spot, Leaf Spots, Other News

After a long, cool, wet spring, the turf did not enjoy the sudden jolt of hot weather. Leading the disease list this week are diseases associated with stress, especially root and crown diseases. Anthracnose is widespread and rapidly developed into the basal or crown rot stage. Fact sheets on this disease are available in the Disease Fact Sheet section of this web site.

Take-all patch, that probably began in the spring, caused bentgrass to show symptoms when the heat hit. Summer patch was also widespread throughout NY and New England on annual bluegrass (Poa annua) in greens, fairways, and athletic fields. Necrotic ring spot has been diagnosed on Kentucky bluegrass sodded lawns. All three of these diseases attack and impair the root system, so plants can collapse quite quickly in heat. Syringing, spiking, hydrojecting, skipping the clean-up pass, dethatching, and other stress-reducing activities will help the plants survive and grow healthy new roots in the cooler week ahead. Fungicides for curative action are thiophanate-methyl or azoxystrobin (Heritage™), but they must be watered-in to the roots while still wet on the leaves.

Leaf spot can progress into a crown and root rot in heat stress and where turf is kept too wet with excessive irrigation or in low areas. Bipolaris, Drechslera, Curvularia, Fusarium and Leptosphaerulina species are all widespread and active on stressed lawns and athletic fields.

The UMass Turf Disease Diagnosis Lab will be open all next week (July 14-18).

Plant Health Progress is a new online journal that is part of the Plant Management Network (www.plantmanagementnetwork.org ). The current issue includes a research paper on the use of a plant defense stimulator (acibenzolar-S-methyl) and organic fertilizers along with different bentgrass cultivars to try to reduce fungicide needs in the control of dollar spot. Fungicides will remain necessary, but progress is being made. This is worthwhile reading for those of you who need to answer people about why you spray so much.

The article, “Dollar Spot in Four Bentgrass Cultivars as Affected by Acibenzolar-S-Methyl and Organic Fertilizers” can be found at:

http://www.plantmanagementnetwork.org/pub/php/research/2003/dollar

Check out the site and see what other useful information is available. For example, subscription to this website includes direct access to all the Fungicide/Nematicide Tests conducted across the country (searchable by plant and disease) and the Biological/Cultural Tests which report disease resistance and biological control product evaluations by plant pathologists. After several weeks of posting, free materials go into a subscription-based archive. Subscriptions are $45/year.

- Submitted by: Dr. Gail Schumann