Ecology and management of earthworm casting on sports turf

Earthworm activity is beneficial in most natural and agricultural systems, but excessive earthworm casting is a problem on sports fields worldwide. Expulsion of soil-rich earthworm fecal matter, or casts, as mounds of soil on the turf canopy can muddy the surface, reduce photosynthesis, and lead to thinning, weed invasion and surface softening. Casts affect ball roll on sports fields, cause fouling of maintenance equipment, and dull mower blades. Build-up of cast material on reel mower units can affect height and quality of cut. Casting activity is dependent on environmental conditions such as soil texture, temperature, moisture, pH, and organic matter. Response to environmental conditions varies by species. Management options are limited, because no pesticides are specifically labeled for earthworm control at this time, and cultural control methods such as soil modification, turfgrass clipping removal, and sand topdressing have limited and inconsistent efficacy. Products containing plant-derived saponins and irritants show promise for earthworm management. Pest management practices to mitigate excessive earthworm casting will likely need to be species-specific, but limited knowledge of earthworm identification by end-users further inhibits the efficacy of control measures.