Yellow appearance progressing to red, then brown; elongated pustules enlarge in rows parallel to veins, that rupture leaf epidermis; reddish-brown spores; as pustules mature, they turn brown to black; heavily infested turf becomes thin with an overall yellow-orange to reddish-brown color; infected leaves turn yellow, wither and die; powdery material rubs off easily on fingers, shoes , and clothing
HOST GRASSES:
Major Hosts: Kentucky bluegrass, Perennial ryegrass, Zoysiagrass
Others: Bentgrasses, Fescues, Tall fescue, Bermudagrass, Bluegrasses, St. Augustinegrass, Centipedegrass
DISEASE CYCLE:
Shoot attacking fungus; rust infections are most severe on slow growing grasses; rust fungi may overwinter in infected plants or be introduced into lawns each year by wind blown spores; infection of leaf blades favored by moderate temperatures (68 to 85 degrees) and extended wet periods; once infection occurs, slightly higher temperatures favor symptom development; some fungi species are host specific-bermudagrass rust, St. Augustine rust, etc..; some fungi only attack certain part of plant; spring and fall fungus--typically
FACTORS THAT MAY PROMOTE DISEASE DEVELOPMENT:
Moist, humid, moderate temps (68 to 85 degrees); low to deficient nitrogen; partially shade areas; infrequent close mowing; excessive thatch; slow growth; moisture stress
CULTURAL CONTROL:
Increase nitrogen judiciously to sustain moderate shoot growth; raise cutting height; control thatch; avoid water stress; avoid shaded areas or prune shaded areas; mow frequently to sever infected leaf tips and retard spore formation; resistant cultivars
CHEMICAL CONTROL:
Fungicides need to applied early in disease development
| Specific Fungicide Recommendations | |||
|
Fungicide (chemical name) |
Efficacy |
Application Interval |
Example of Products (trade names) |
| Azoxystrobin | Good | 7 to 21 days | Heritage |
| Mancozeb | Good | 7 to 14 days | Fore, Dithane, Protect |
| Myclobutanil | Good | 14 days | Eagle, Immunox |
| Propiconazole | Good | 7 to 14 days | Banner Maxx |
| Triadimefon | Good to Excellent | 14 to 28 days | Accost, Bayleton |
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.