Crown Rot Anthracnose

Disease

Anthracnose, Basal Rot Anthracnose

Colletotrichum cereale

Photos

Anthracnose can occur as both a foliar infecting and crown infecting disease. Crown or basal rot anthracnose attacks the crowns of grass plants, unlike the more common anthracnose, which primarily attacks the foliage. Symptoms first appear as bronze-yellow spots in the turf, usually about the size of a dime. Spots can become larger if disease persist forming irregular shaped areas of affected turf. Examination of infected plants reveals darkened rotted crowns. Pepper-like acervuli can often be seen on stems and crowns of infected plants.

The disease occurs primarily on annual bluegrass throughout most of the world. However it has been reported to be a widespread problem on creeping bentgrass in the eastern and southeastern United States. It is most noticeable on putting green-height mowed turf, and appears to be most severe on greens with compaction problems or poor internal drainage. The disease usually appears following excessive rainfall or irrigation events, and can occur throughout the growing season in both cool and warm temperatures.

Crops Affected: turf

Damage

The location of this disease is golf courses. General symptoms are circled, spotted, wilted, or irregular grass. Foliar symptoms are spots, and the grass turning yellow, brown, or orange. This can occur during the months of April, May, June, July, August, September, October. Hosts of the disease are Kentucky Bluegrass, Creeping Bentgrass, and Annual Bluegrass.

Management

Raising the mowing height helps to reduce the severity of disease in some cases. Using irrigation syringe cycles or light hand syringings during the day and avoiding deep nighttime irrigation can reduce the incidence of crown rot anthracnose. Improving the internal drainage and eliminating compaction in a putting green will also reduced the severity of disease. No known resistant cultivars of creeping bentgrass or annual bluegrass.
Many fungicides are effective in controlling crown rot anthracnose, however timing of these applications are important. The best results have been from fungicide applications made prior to symptom expression. Contact fungicides such as chlorothalonil products, which inhibit spore germination, can limit disease outbreak severity. Thiophanate-methyl fungicides applied through drench application have provided the most effective treatment in stopping disease proliferation. The demethylation inhibiting (DMI) fungicides have also shown to be effective, among others.
It should be noted that iprodione and vinclozolin fungicides are not effective against anthracnose and plants with severely infected crowns will die, regardless of treatment.

MSU Extension Turf