Annual bluegrass (a
common weed in turf), Kentucky
Anthracnose appears in the lawn as irregular patches of brown grass,
2 to 12 inches (5 - 30 cm) in diameter. Brown or tan blotches are
present on the leaves. Black, spiky fruiting structures (acervuli)
occur on dead grass blades and are key to identifying this disease.
The older growth is affected in advance of newly developed leaves.
The new growth may remain green.
Conditions favoring disease
Anthracnose is favored by warm temperatures ranging from 80°
to 95°F and occurs primarily in the spring and summer. Extended
periods of leaf wetness, soil fertility, high compaction, and high
soil salinity contribute to disease development.
Prevention and management
Practices that limit the length of time that leaves remain wet after
irrigation will reduce infection. Reduce shade by pruning trees and
shrubs that block air movement or light to the grass. Improve
soil aeration. Avoid drought stress and do not water at night.
Fertilize using the recommended
rate for your turf species. Avoid fertilizing during warm months.
Increase your mowing height to
reduce stress. Choose turf species other
than bluegrass that are not susceptible to the disease. If the problem
occurs on weedy annual bluegrass in your lawn, control the annual
bluegrass. Fungicides are generally not warranted in home lawns.
For more information on lawn diseases, refer to:
Pest Notes: Lawn Diseases:
Prevention and Management