Date: July 25, 2001
Category: Diseases Subject: Summer Patch, Brown Patch, Pythium, Gray Leaf
Spot
SUMMER PATCH has been diagnosed on golf courses in the area. This is a
stress-related, root disease of annual bluegrass. Curative control is
best using azoxystrobin, watered-in, but keep in mind that badly infected
plants may not recover. The long term solutions area to prevent stress
(compaction, excessive thatch, insufficient water) and/or replace the
Poa with bentgrass. DROUGHT symptoms unrelated to any obvious fungal pathogens
have also been observed. Many lawns are going dormant, but drought problems
are also common on golf courses where irrigation systems do not deliver
uniform water. Symptoms are most common where roots are shallow and thatch
is thick. Even the best irrigation systems have trouble replacing a good,
soaking rain which has not occurred in most areas for a while now. The
good news is that the next few days will be cooler. When nights dip into
the 50s, both BROWN PATCH and PYTHIUM BLIGHT will no longer be active,
so you can probably save yourself a fungicide spray tomorrow. Watch perennial
ryegrass areas for GRAY LEAF SPOT. It has not been confirmed in New England
yet this season, but could develop rapidly if we get some rain.
