Anthracnose

The Issue

Causal Agent: Colletotrichum cereale

Hosts: Poa annua, bentgrass, Kentucky bluegrass, fine-leaf fescues, perennial ryegrass

Epidemiology: Anthracnose develops over a range of temperatures and was generally considered a disease of poa annua only. Anthracnose has now been observed on creeping bentgrass (generally older varieties). Symptoms of basal rot develop at cooler temperatures (15 to 25°C), and foliar symptoms occur at temperatures above 26°C.

Target: Foliage, crowns, stolons and roots

Foliar Blight Evidence: On poa annua symptoms include a yellowing to reddish brown discoloration of leaves and a general thinning of the turf. Leaves die from their tips down. On creeping bentgrass symptoms appear reddish-tan and in other cases, older leaf blades are completely water-soaked.

Basal Rot Evidence: Crown tissues become infected and scattered plants or small patches of plants turn yellow and die. Close examination of the infected stem base reveals a water-soaked black rot of the crown tissue while the leaf blades exhibit no lesions.

Foliar Blight Clues:  Distinctive fruiting bodies (acervuli) of the fungus with their protruding, black, hairlike structures (setae) can be observed with a hand lens.

Basal Rot Clues: Close examination of the infected stem base reveals a water-soaked black rot of the crown tissue. On creeping bentgrass, the stolons may also be affected.