You Are Here: Management Updates 2005 Archive August 16, 2005

Date: August 16, 2005
Category: Diseases
Subject: Summer Stress Diseases

The recent round of high temperatures and high humidity has resulted in the summer stress diseases, anthracnose, summer patch, and summer bentgrass decline (SBD) being seen at the Turfgrass Diagnostic Lab.

Conditions necessary for anthracnose infection are also those that stress the turf-high temperatures, compacted soils, and low fertility. Fertilize with balanced fertilizers, especially avoiding low levels of potassium and phosphorous. Apply a systemic fungicide (fenarimol, propiconazole, thiophanate-methyl), water in thoroughly, and let dry. Follow with a separate application of a contact fungicide (mancozeb, chlorothalonil).

Damage due to summer patch activity occurs in the spring and fall, but symptoms develop when the soil temperature reaches 70˚ F. Adequate nitrogen is essential for managing summer patch; slow release forms are most beneficial. Reduce compaction and improve drainage. If the temperature is high and soil moisture adequate, consider afternoon syringing to cool the turf and reduce summer patch severity. Applications of thiophanate-methyl at regular intervals best manage summer patch.

SBD is a physiological syndrome evidenced by thinning of the turf canopy, yellowing of leaves, and death of roots. The cause has been attributed to many factors including high soil temperature, excessive or deficit soil moisture, poor soil aeration, and accumulation of organic matter in sand greens. Reduce soil temperatures by syringing or fans. Reduce organic matter accumulation by twice annual core aeration followed by heavy top dressing.

Submitted by: M. Bess Dicklow
UMass Extension Plant Diagnostic Labs

DISCLAIMER - As always, it is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. The author and the University of Massachusetts are not liable for any consequences of any pesticide "recommendations". Mention of any trade name is not to be considered endorsement of a product

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