You Are Here: Management Updates 2001 Archive August 10, 2001

Date: August 10, 2001
Category: Diseases
Subject: Bentgrass Dead Spot, Gray Leaf Spot

Dr. Noel Jackson reports the first diagnosis of BENTGRASS DEAD SPOT in New England for this season. This new disease is apparently restricted to new (<6 yrs old) bentgrass. Unlike dollar spot, it does not produce abundant foliar mycelium. Spots generally do not coalesce. Infected leaves usually are full of tiny black fruiting bodies. Preliminary fungicide information suggests that Banner (2 oz), Cleary's 3336 (8 oz) + chlorothalonil, chlorothalonil (4.9 oz + iprodione (5.3 oz) can be used weekly until disease is controlled. Healing of dead spots can take quite a bit of time. If you see a few early spots, remove them to prevent spread of spores. If you are not sure of the diagnosis, send a sample to Dr. Jackson at URI. If you have a good sample for class, please send a spot or two to me (Gail Schumann for fall classes. If you are not sure if it's dollar spot or not, there are two clues: 1) BDS attacks only bentgrass, so if Poa is affected it's probably dollar spot; 2) put a plug in a plastic bag with a moist paper towel overnight. Sprinkle a little water on the turf surface. Close bag, but leave a "bubble" of air over the turf surface. If you see white mycelium in the morning, esp at the edge of the spot, it's dollar spot, not BDS.

GRAY LEAF SPOT has been reported on a ryegrass athletic field in Kentucky this week. If you have perennial ryegrass in lawns, athletic fields, fairways, etc. watch closely and get an immediate diagnosis from Dr. Jackson at URI (see Diagnostic section for phone and address). I will report New England outbreaks as soon as I hear about them. Do not rely on field diagnosis. If you need to spray right away, take a sample first for confirmation. Keep in mind that resistance to Heritage and Compass has been documented.

The hot weather should break this afternoon, and it should remain moderate through next week. Any night below 59 will stop brown patch. Tonight will stop Pythium. Just a few more hours...Good luck.

- Submitted by: Dr. Gail Schumann