What are they and where have they come from?
Why are worm casts a problem for lawn owners?
It is not the activity of the worms naturally aerating the soil beneath the grass surface, but the detrimental effect of their casts that cause the problems. The soil making up the casts is very slimy as it consists of soil and the natural secretions from the worm’s digestive system. Left on the surface of the lawn, the casts will be smeared across the grass through the actions of mowing and walking on the lawn. The end result is that worms are capable of pushing up an incredible volume of soil by way of their casts so it does not take long for the surface of the lawn to become really muddy and slippery.
When do the casts appear?
As the soil air to water ratio changes in the more traditional autumn months, you will notice an increase in worm cast activity. The wetter the autumn or winter, the greater the worm activity will be. The root zone of the lawn will become spongy as the worms undermine the upper surface and mowing will become difficult, especially with a cylinder mower. The use of the lawn will diminish as a result of the difficult surface conditions.
What can be done to control the worm activity?
Worms prefer rich organic soils that are full of bacteria and soil flora and fauna. Increased populations can be found in heavier clay soils and wetter soils.
Prevention is always better than cure - leaving autumn leaves on the surface of the lawn for long periods will encourage worms to literally pull the leaves into their burrows. Leaving lawn-mowing clippings on the lawn will increase worm activity as the dead and decaying matter is increasing the organic matter content of the soil – a rich food source for worms.
Culturally, you can switch the casts off the lawn on a dry windy day with a besom broom or bamboo cane. This is not 100% ideal if the there are numerous casts though!
The best solution is to apply a worm cast control product in late September/October. The control product does not kill the worms but creates a barrier in the soil that the worms are not keen to pass through, as the control product is an irritant to their system. The worms will stay deeper in the soil and not cast.
Domestic Lawn Use - CastClear Lawn Worm Cast Suppressant
Professional Turf Use - Contract Pesticide Application Service - Weed Free
The pesticide control product will last around two to three month’s dependant upon the level of rainfall over the autumn/winter months. Do not be tempted to spray too early in September. CastClear will need re applciation every 10 - 20 days until the worm cast activity has been eradicated.
The pesticide control product is only available to professional pesticide users that hold a Certificate of Competence to purchase and apply such products.
The results following worm cast control application are quite remarkable. Adopting a worm cast control programme maybe once of twice a year in really high activity areas will not only go a long way in securing the grass cover over the autumn and winter months but lengthen the actual mower season.
Increased maintenance costs
As the worm casts are predominately dirt, it will not take long for the cylinder mower blade to loose its sharp edge as it literally grinds away the leading and cutting edge, thus increasing maintenance costs.
The worm casts are a bacteria rich soil, which means that weed seeds are easily able to germinate in them, thus increasing the number of weeds the following spring. The casts when trodden on can be squashed and then smear on the surface of the lawn thus smothering any grass that was there beforehand – so in time you can literally loose your lawn to a sea of worm casts that turn to mud!
An amazing fact about earth worms –
Worms are the richest source of protein known to man, which explains why I spent such a long time trying to eat them when I was young….