Algal scum (algae - Nostoc spp., Oscillatoria spp., Chlamydomonas spp., Hantzchia spp., others): Algae do not infect turfgrasses but they are highly invasive and often out-compete grasses for space in wet or shaded environments. Algal scum can be a chronic problem on greens, especially those with poor air circulation, compacted soils and wet areas. Their growth is encouraged by extended periods of rainy, overcast and warm weather. Algal scums slow water infiltration, keep thatch wet for extended periods of time, and impede oxygen and other gas diffusion into and out of soils.
Management: Control requires alleviating wet soil conditions by improving drainage, aeration, and proper irrigation practices. Improve air circulation by selective pruning or removal of trees and shrubs. Chemical applications must be done carefully since many will cause severe burning of turf.