You Are Here: Management Updates 2000 Archive July 28, 2000

Date: July 28, 2000
Category: Diseases
Subject: Summer Diseases, Gray Leaf Spot, Copper Spot, Summer Patch

The weather for July appears to be the coolest on record and certainly one of the wettest. We are avoiding a lot of the typical summer stress, so the turf can outgrow many of its summer problems, but the moisture is certainly conducive to fungal activity. This weekend will be warm and humid with more rain predicted for the next several days. BROWN PATCH can be quite active in warm- not necessarily hot- wet weather as long as night temperatures remain above 60 F. Avoid any heavy nitrogen applications during this time. LEAF SPOT and BROWN PATCH are both favored by high N conditions, especially when you have little control over leaf wetness.

ANTHRACNOSE continues to plague many golf courses. It appears to have quickly moved into a crown rot stage in many situations. When this happens, plants may continue to yellow and die even after appropriate fungicide treatment. See previous messages for more information on this disease.

GRAY LEAF SPOT has NOT been seen yet this season. We are monitoring throughout NJ, PA, NY, CT, and MA for the disease and will post a warning as soon as it is identified. It attacks only perennial ryegrass and tall fescue, and so far has been a problem primarily on golf courses rather than lawns and athletic fields. It is impossible to separate this leaf spot disease from typical Helminthosporium-type leaf spots without a microscope. These other leaf spot problems are currently widespread due to the wet weather.

COPPER SPOT was diagnosed on newly planted L-93 bentgrass from northern Vermont. It looks similar to Fusarium patch (pink snow mold)- small coppery spots. It can follow water patterns because of its prolific spore production. Control is similar to dollar spot. It does not produce the typical greasy spots of Fusarium patch. It is most common on velvet bentgrass in coastal areas. Watch L-93 to see if you see this disease.

SUMMER PATCH was diagnosed this week for the first time from yellowing Poa annua from a golf course fairway.

- Submitted by: Dr. Gail Schumann