Earthworms In Turf

There are 28 commonly found species of earthworm in the UK, however only 8 of these create casts and of these 8 there are only 4 that commonly cause problems with casts on turf. Earthworms have an important role in helping to aerate soils, reduce compaction, improve water penetration and infiltration rates, processing organic matter and reducing thatch, very much like the role of the greenkeeper, so it is important any treatment has a selective action affecting only any casting issues.

The 4 common casting worms are:

Lob Worm (Lumbricus Terrestris)

Lives in vertical burrows up to 3 metres deep. They feed on fallen leaves and decaying organic matter, such as thatch accumulation. The most common earthworm for causing casting issues in turf. Population approximately 20 - 40 per sq.m.

Black Headed Worm (Aporrectodea Longa)

Lives in open alkaline grassland and cultivated soil, size 12 cm long and feeds on organic matter in the soil. The black headed worm has a population of approximately 5 – 20 per sq.m.

Grey Earthworm (Aporrectodea Calignosa)

Feeds on soil and recycles it having taken out organic material. They make horizontal burrows in the soil to move around feeding sites. They are a grey/pink colour and look somewhat washed out and anaemic.

Microscolex Phosphoreus Worm

The one that leaves those very tiny little casts on the golf greens. Strangely it will glow in the dark when touched. Produces very small casts mostly during the day during August and September, they favour sandy root zones. Often not too much of a problem as their casts are small and sandy and therefore easily break down and tend not to smear.

The Anatomy Of The Earthworm

The Life Cycle Of The Earthworm

Earthworms are hermaphrodites but when two earthworms are ready to mate they each produce a mucus around themselves and then hold on to each other’s saddles. The mucus that they produce is an ideal environment for them to be able to exchange sperm. They hold their partners sperm in the mucus. As the earthworm moves along the mucus and sperm mixture comes off at the head end. As it does so, it picks up the eggs which mix with the sperm of the earthworm that it mated with. This mucus sheath forms a lemon shaped cocoon and fertilisation of the egg occurs within this cocoon.

The baby worms, called hatchlings, emerge and burrow into the soil where they grow into juvenile then mature earthworms. Each earthworm has between 1 and 20 eggs in each cocoon and can produce up to 80 cocoons in a year. Each earthworm lives for between 4 - 8 years.

The Problem With Worm Casts

The casts of earthworms can cause a number of problems for turf managers and for sportsmen. Playing surface disruption by leaving little piles of soil in the way. Getting mud collecting on shoes and playing equipment. Causing a slippery surface. Damage caused by Foxes and particularly Badgers looking for earthworms to eat can be catastrophic, with turf areas being ripped apart.

Mole activity will be a major issue as surface levels can be ruined caused by their burrowing activities and leaving mole hills on the surface. Damage to machinery, particularly with casts going through cutting machines and collecting on the rollers effecting height of cut. Each earthworm cast that is smeared on the surface is an ideal seed bed for weed seeds. Increased bird damage (Starlings and Crows) caused by pecking and tearing of the turf.

Cultural Practices To Reduce Earthworm Casts

Cultural practices along with other accompanying techniques are now at the forefront of earthworm cast management for the turf manager, these include: