Microdochium Patch

The Issue

Causal Agent: Microdochium patch (Microdochium Nivale)

Hosts: All turfgrasses in Canada ; however poa annua is more susceptible than creeping bentgrass

Epidemiology: Microdochium patch can be observed year round in some cool, wet regions. Most severe when temperatures are below 16°C coupled with slow growing turf.

Target: Foliage

Evidence: Circular patches first appear as small, water-soaked spots, less than 5 cm in diameter, rapidly changing from orange brown to dark reddish brown and finally light grey or tan. Spots can sometimes appear in linear streaks due to the dispersal of conidia (spores) by mowers.

Clues:  Ringlike patches can appear on low-cut turfs. Under very wet conditions, white mycelium may be present on matted leaves. Sunlight can induce the production of pink mycelium which results in the classic ringlink patch with a pink outer margin.