How to get ahead of anthracnose

Bruce Clark, director, Rutgers Center for Turfgrass Science.

Clarke told attendees that anthracnose epidemics have been so serious in some New Jersey locations that fungicides were unable to control the disease at labeled rates.

"This has resulted in extensive damage and major disruptions in play, particularly on greens," he says. He offered several non-chemical and chemical tips to get ahead of anthracnose.

Water is one answer. "Drought stress predisposes turf to anthracnose," Clarke says. He urged turf managers to do everything possible to avoid late-day wilt stress with proper irrigation.

He said tree root competition is another factor associated with decreasing turf vigor that may aid anthracnose.

Low mowing heights may be unavoidable, but severe anthracnose outbreaks seem more likely on greens cut to one-eighth inch or lower. Clarke said too frequent cutting — double and triple cutting — also causes trouble.

While there is no hard-and-fast data, the use of grooved rollers seems to dispose grass to anthracnose. For the time being, avoid grooved rollers in stressed areas.

Clarke said that turf managers should consider increasing N applications from every two weeks to once a week. He recommends trying a 0.75-1.5 pound rate of slow-release N in the Fall and Spring.

"Where possible, raise the mowing height when turf is under stress," Clarke said. As little as an extra one-thirty-second of an inch can help. It also will help fungicides do their job better.

p> On sites with a history of problems, Clarke said fungicide programs probably have to start two or three weeks before symptoms develop. This usually means early-to-mid May in the mid-Atlantic region.

For more specifics on products and application rates, see Clarke's four-page fact sheet called "Chemical Control of Turfgrass Diseases," Rutgers Cooperative Extension, April 2000 (PDF, 44kb).