Brown Patch
DISEASE SYMPTOMS:
Circular or irregular shaped patches of light brown, thinned grass; turfgrass can be yellowish and may have a smoke-ring on outside edge – especially in the morning hours on cool season grasses; turf in the center of the ring may recover, leaving a ring effect; spreads rapidly; patches up to several yards in diameter; leaf sheaths become rotted and a gentle tug on the leaf blade easily separates from the runner; usually does not discolor roots; fungus attacks the base of the leaf sheath; get a water soaked , dark grass that soon wilts and turns brown.
HOST GRASSES:
Major Hosts: St. Augustinegrass, Zoysiagrass, American buffalograss, Annual bluegrass, Creeping bentgrass, Colonial bentgrass, Tall fescue, Perennial ryegrass. Others: Bermudagrass, Centipedegrass, Bahiagrass, Fine fescues, Kentucky bluegrass.
DISEASE CYCLE:
Disease develops rapidly when air temperatures are between 75 and 85 degrees and wet conditions are present-Spring, Fall and sometimes mild Winter conditions; generally subsides when air temperatures exceed 90 degrees; foliar attacking fungus; occurs following extended leaf wetness for 10 hours per day for 2 to 5 days; leaves, stems, crowns and roots may be infected.
FACTORS THAT MAY PROMOTE DISEASE DEVELOPMENT:
Cool, wet or moist conditions; leaf blades with dew or free water on them for extended periods; excessive nitrogen and irrigation; lack of air movement; poor soil drainage; excessive thatch; compacted soils-lack of aerification; presence of active fungi; vigorous growth of turfgrass.
CULTURAL CONTROL:
Improve soil drainage; remove dew in early morning by mowing or watering or whipping; cultivate by coring or slicing; avoid excessive nitrogen and irrigation; reduce shading; improve air movement.
CHEMICAL CONTROL:
Most fungicides will do an effective job if used on a preventative basis-hard to destroy the fungus once it is established on the turfgrass. Many fungicides labeled to treat Brown Patch-only those which seem to be most effective are listed below.
| Specific Fungicide Recommendations | |||
| Fungicide (chemical name) | Efficacy | Application Interval | Example of Products (trade names) |
|---|---|---|---|
| Azoxystrobin | Good to excellent | 14 to 28 days | Heritage |
| Triadimefon | Fair to good | 30 days | Bayleton |
| Myclobutinil | Good to excellent | 14 days | Eagle, Immunox |
| PCNB | Good to excellent | 21 to 28 days | Terraclor, Turfcide |
| Mancozeb | Fair to good | 7 days | Fore, Dithane, Protect, Penncozeb |
| Fenarimol | Fiar | 7 to 14 days | Rubigan, Patchwork |
REFERENCES:
- Duble, R. L. 2001. Turfgrasses-Their Management and Use in the Southern Zone. Second Edition. Texas A&M University. College Station, Texas.
- Emmons, R. D. 2000. Turfgrass Science and Management. Third Edition. Delmar Thomson Learning. Albany, New York.
- Turgeon, A. J. 2002. Turfgrass Management. Sixth Edition. Prentice Hall. Upper Saddle River, New Jersey.
- Beard, J. B. 2002. Turfgrass Management for Golf Courses. Second Edition. Ann Harbor Press. Chelsea, Michigan.
- Taylor, G. R. – Editor. 2000. Turfgrass Pesticide Recommendations 1999-2000. Extension Publication SCS-1991-01. Texas A&M University. College Station, Texas.
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