You Are Here: Management Updates 2000 Archive May 19, 2000

Date: May 19, 2000
Category: Diseases
Subject: Late-Spring Diseases, Pythium Root Rot

It's difficult to write a disease message that might be almost meaningless in one or two days because the weather keeps changing from one extreme to another. On Friday, May 19, the weather is very wet and getting progressively cooler as the day goes on. Reports of typical diseases for this kind of weather are widespread: Fusarium patch (pink snow mold), yellow patch (cool-weather brown patch), red thread, and leaf spot progressing into melting-out. Take-all patch was diagnosed on wet greens where pH was relatively high. Algae has established itself in some very wet greens or where rain has been persistent. Although algae is a green plant and not really a disease, it can interfere with turf growth and is symptomatic of excessive moisture. Chlorothalonil and mancozeb fungicides can help reduce algae, but water management is the long term solution.

Only a few days ago, samples were still showing problems related to the short hot spell we experienced. A number of golf courses with thatchy greens had green rings of fairy ring and/or the associated yellowing rings due to drought stress. Wetting agents, aeration, and careful handwatering can help reduce these symptoms.

Pythium root rot continues to be diagnosed in some samples, but other areas of poor turf growth, especially annual bluegrass, do not appear to be caused by a fungal disease. They are probably related to the temperature fluctuations that interfere with water and nutrient uptake.

- Submitted by: Dr. Gail Schumann