DISEASE SYMPTOMS:
Circular patches 1 to 3 ft. in diameter, sunken, with bleached-straw color; appears at spring greenup; roots and stolons may have black rot; regrowth into infected areas are sluggish and often weedy; short stubby roots where new stolons develop; patches appear in same area and expand each year for 3 or 4 years; some green grass may appear in middle of patch after several years to make it look similar to fair ring; disease mostly on mature turf that is intensely managed
HOST GRASSES:
Major hosts: Bermudagrass, American Buffalograss
Others: Common Carpetgrass, Kikuyugrass, St. Augustinegrass, Zoysiagrass
DISEASE CYCLE:
Root, rhizome, and stolon attacking fungus; very slow turf recovery unless soil is disturbed by turf cultivation; infection occurs in fall and disease appears in spring during shoot green up; longer the dormancy and colder the winter, greater the severity of the disease; cool subtropical climates where fall and winter temperatures favor a prolonged period of winter dormancy; a persistent soil toxin has been isolated
FACTORS THAT MAY PROMOTE DISEASE DEVELOPMENT:
High late summer-early fall nitrogen fertility; dry soil conditions; excessive thatch; cool temperatures and moist soil, spring and fall; poor drainage
CULTURAL CONTROL:
Maintain moist soil and moderate nitrogen fertility level in fall; control thatch; use less susceptible cultivars; Ammonium based nitrogen fertilizer combined with potassium reduce disease over time; pH of 5.8 to 6.2 in soil is best; maintain good drainage
CHEMICAL CONTROL:
Repeated applications of fungicides; application needs to take place beginning in late summer when disease is thought to be active.
| Specific Fungicide Recommendations | |||
|
Fungicide (chemical name) |
Efficacy |
Application Interval |
Example of Products (trade names) |
| Azoxystrobin | Good to excellent | 28 days | Heritage |
| Fenarimol | Good to excellent | -- | Rubigan, Patchwork |
| Myclobutanil | Good to excellent | 28 days | Eagle, Immunox |
| Propiconazole | Good to excellent | 30 days | Banner Maxx |
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.
Decker, H. F., Decker, J. M. 1988. Lawn Care-A Handbook for Professionals. Prentice Hall. Englewood Cliffs, New Jersey.