You Are Here: Management Updates 1998 Archive July 10, 1998

Date: July 10, 1998
Category: Diseases
Subject: Summer Diseases

The moisture and warmer temperatures continue to keep fungi active and diseases appearing. Anthracnose, especially in its crown rot stage, is still common in stressed turf (compaction, excess thatch). Even with fungicides, recovery can be slow with crown rot.

Many complaints about fairway turf. Brown patch and Leptosphaerulina blight are common in moist and poorly drained areas. When nights cool off (below 58), brown patch development slows or stops which may confuse symptoms after a few warmer days. Leptosphaerulina may be identified in the field as primarily a tip blight with abundant tiny dark fruiting bodies in infected leaves. In stressed plants, the entire blade may be affected when moisture is prolonged, but serious damage is not a concern. Both problems can be reduced by standard fungicides such as iprodione and chlorothalonil, but treatment is probably not necessary.

A number of samples from fairways include turf, especially annual bluegrass, that is growing in compacted soil with very shallow roots. Some of the plants show signs of nitrogen stress after the heavy rains. Small applications of fertilizer and afternoon syringing may be necessary to assure their survival in hot weather. The long term solution is a deeper root system through more frequent core aeration.

Some plants appear to have roots infected by the fungus that causes summer patch, but above ground symptoms have not been observed at the diagnostic lab this week. Be on the watch for this problem where soil is compacted, roots are shallow and if temperatures suddenly go up for several days following rain. Thiophanate-methyl and azoxystrobin (Heritage) may offer curative action if roots and crowns are treated before damage is severe.

- Submitted by: Dr. Gail Schumann