Anthracnose Leaf Blight and Basal Rot

Grass Affected

All turfgrasses

 

Diagnostic Description

  • The casual fungus can infect leaves, sheaths, and tillers. In creeping bentgrass and Poa annua, stolons and crowns also may be rotted (anthracnose basal rot). Leaf infection appears as reddish-brown to brown lesions surrounded by a yellow halo. Lesion size may span the blade width and often one lesion will cause complete yellowing of a blade. Tiller infection results in stem girdling and the subsequent appearance of small, yellow patches of turf.
  • The casual fungus can sometimes be observed with a hand lens. It will appear as dark, cushion-like reproductive structures (acervuli) with black spines (setae) extending from the margin of the cushion. Plants with anthracnose basal rot may have deep-seated infections not readily diagnosed with only a hand lens which is most active in hot weather on bentgrass and Poa annua.

 

Conditions Favoring Infestation and Typically Yearly Occurrence

Favored during periods of limited grass growth such as summer weather on cool-season grasses or fall for warm-season grasses. May also occur when grasses are under stress from insects, compaction, localized dry spots, nematode infestations, or other stress factors such as excessively low mowing heights, surface traffic, and inadequate irrigation and nitrogen fertilizer