Anthracnose foliar blight and basal rot

Anthracnose foliar blight typically occurs during mid-summer and attacks the leaves and stems of most cool-season turfgrass species. Particularly severe cases can develop on annual bluegrass fairways on golf courses. Anthracnose basal rot can occur during spring, summer, and fall and develops in the crowns, stem bases, and roots of annual bluegrass and creeping bentgrass, usually on golf course putting greens.
Symptoms and signs. Anthracnose foliar blight appears as irregular yellow or bronze patches of diseased turf. Symptoms on individual plants first appear as yellow or red lesions on the oldest (outermost) leaves, then progress to a blighting of younger leaves and shoots. Occasionally, fungal fruiting structures called acervuli can be observed with a good quality hand lens on diseased leaves and stems.Acervuli resemble small, black pin cushions and are the site of spore production.
Anthracnose basal rot symptoms vary depending on the grass species affected. On annual bluegrass, symptoms appear as a bright yellowing of the turf in irregular patches.Affected bentgrass turf typically appears as irregular red or bronze patches and rarely appears yellow. On individual plants affected with anthracnose basal rot, a dark brown or black color is present at the base of the plant. As the disease worsens, the darkening (rotting) progresses up the stem and acervuli can be observed with a hand lens on stem and leaf tissue.
Disease cycle. The causal fungus, Colletotrichum cereale, survives the winter as dormant resting structures called sclerotia and as dormant mycelium in infected plant debris. During early spring outbreaks of anthracnose basal rot, the fungus, which may have overwintered in the plant, initiates infection at the base of the plant. Outbreaks of anthracnose foliar blight and/or basal rot can result when spores produced in acervuli are dispersed by splashing water or tracked by mowing equipment from one area to another. These spores then germinate and cause new infections on other plants.Anthracnose is likely to occur when plants are growing slowly (during periods of hot and cold temperatures), during overcast periods, and in high humidity conditions.