Earthworm Casts

Causal organism: three major species most closely associated with casting:

Lumbricus terrestris
Aporrectodea caliginosa
Aporrectodea longa

 

Problem	Earthworm casts
Host grass types	All turf types
Symptoms	Some species of earthworms leave casts on the turf surface and this can have a negative impact on the performance and quality of the turf (unevenness, deterioration under traffic, weed invasion, mole activity).

 

Background information

1. Earthworms have an important role in helping to aerate soils, reducing compaction, improving water penetration and infiltration rates, processing organic matter, and reducing thatch.
2. Earthworms come to the surface under moist soil conditions (e.g., in late fall and winter) and retreat downward in dry weather.
3. Earthworm casting is increased: if grass clippings are returned, when organic fertilizers are used, in liming or using alkaline water for irrigation.

 

Management strategy to reduce the likelihood of attack

1. Reduce thatch in a programmed approach to minimize food sources for earthworms.
2. Make minimal use of organic amendments.
3. Lower the soil surface pH to discourage earthworm activity by using acidifying fertilizers.
4. Minimize the amount of clippings returned to the soil (organic material) by use of slow-release fertilizers or plant growth regulators.
5. Use sand top dressings to help create casts that scatter and disperse.
6. Brush or switch to disperse casts when dry.

 

Preventive strategy (guidance only)