Up to 12 inch diameter patches; leaves become water soaked, turn reddish-brown , then bleach; pink mycelia may be visible in early morning; autumn forms appear as 1 to 2 inch diameter patches that enlarge; in cool wet weather, the leaves are matted together and are covered with a whitish pink mycelial growth that is slimy when wet; when exposed to light, spots may exhibit a pink coloration; usually kills leaf blades only, unless under extreme conditions; fungus with or without presence of snow or ice cover
HOST GRASSES:
Major hosts: Annual bluegrass, Colonial and Creeping bentgrass
Others: Fine fescues; Tall fescue, Perennial ryegrass, Rough bluegrass, Kentucky bluegrass
DISEASE CYCLE:
Shoot attacking fungus; seed borne pathogen; spread by mechanical means and water splashing; a facultative saprophyte that is active during prolonged cool wet weather from fall to mid spring; common in temperate oceanic climates; occurs most rapidly at temperatures of 32 to 45 degrees ( maximum at 65 degrees); pathogen survives unfavorable conditions as dormant mycelia in living or dead grass plants and debris; infection results from mycelium growth and also from germination of asexual spores that invade through the stomates; not always pink or pale red
FACTORS THAT MAY PROMOTE DISEASE DEVELOPMENT:
Wet humid cloudy weather, cold 32 to 45 degrees; also develops under snow if soil is not frozen; high nitrogen fertility in fall; excessive thatch; soil pH above 6.5; poor drainage
CULTURAL CONTROL:
Use moderate, early fall nitrogen rates to avoid excessive shoot growth; control excessive thatch; remove dew early in morning; improve air movement; maintain soil pH below 6.5; provide surface drainage; mow to normal height at end of season; minimize snow accumulations
CHEMICAL CONTROL:
Not always practical or necessary; if need, several fungicides to choose from
| Specific Fungicide Recommendations | |||
|
Fungicide (chemical name) |
Efficacy |
Application Interval |
Example of Products (trade names) |
| Azoxystrobin | Good to excellent | 14 to 28 days | Heritage |
| Fenarimol | Good to excellent | 10 to 21 days | Rubigan, Patchwork |
| Iprodione | Good to excellent | 14 to 28 days | Chipco 26019, Chipco 26GT |
| Mancozeb | Good to excellent | 7 to 14 days | Fore, Dithane, Protect |
| PCNB | Good to excellent | 21 to 28 days | Terraclor, Turfcide, Defend |
| Propiconazole | Good to excellent | 14 to 28 days | Banner Maxx |
| Vinclozolin | Good to excellent | 21 to 28 days | Curalan, Touche, Vorlan |
REFERENCES:
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.
Decker, H. F., Decker, J. M. 1988. Lawn Care-A Handbook for Professionals. Prentice Hall. Englewood Cliffs, New Jersey.