Carbendazim for Earthworm Control - The Alternatives
The Amenity Sports Turf Industry has had the registration for this useful fungicide pesticide active ingredient, which had a dual use for earthworm cast suppression revoked by the 'they should know better' EU Ministers last year, meaning that you are going to see an abundance of earthworm casts on your lawns, sports pitch & golf course this autumn.
Last year, there was soome evident stock piling on Carbendazim pesticide active so this autumn will be the first period with the biggest worm cast impact seen on turf.
The garden retail product to deter lawn worm casts is CastClear, marketed by The Lawn Company who have sold over 13,000 litres of the product since they entered it into garden retail back in 2012. At that time, there had not been a domestic approved, non-pesticide product in the garden retail industry for some 20 years or so prior to the arrival of CastClear.
The problem with preventing worm casts on larger areas with CastClear at 20 Litres per Hectare is the need to repeat the application every 17-20 days or so at one third of the initial dose rate.
Let's look at the alternatives for solving worm casts on larger areas.
The quick science bit. Both the taste of the pesticide product Carbendazim and non-pesticide CastClear are hated by the earthworms as they go about their business eating up the soil organic matter under the turf surface. The slightly chemical laden soil passes through their digestive tract and as a result, the worms head deeper down the soil profile to get out of the zone where the chemical is being retained by the soil colloids. They expel this soil from their bodies in the form of soil casts on the lawn, and as these soil casts are full of sticky digestive juices, you can see why they are such a problem for lawn lovers and golf courses.
There have been many earthworm control products available in amenity sports turf over the past few decades with trade names like Wormex, Chlordane, Thinsec, Ringer, Mascot Systemic, Turf Clear, Castaway, Syndane, to name a few. Some were persistant for 6 months or so, some for 3 months. Some harmed more than earthworms, some did not. Slowly, one by one, their active ingredients have been withdrawn or banned by UK or EU Ministers for various reasons.
Years ago, gardeners applied Mowrah Meal (Saponins are a natural soap or surfactant found in mowrah meal) Mustard Powder, Chilli Powder, Curry Powder, Soapy Water, the list goes on and currently a lot of trials are being done on sports fields and fairways to see if a natural soil conditioner or nutrient product can deter earthworms from casting. Sulphate of Ammonia and Sulphate of Iron, Sulphur Pellets and Chips, may also have a similar effect on the worms, they don't like the taste of the product in their soil dinner and move away, out of the soil or deeper below the barrier created by the control product.
Here is an interesting article from Golf Course Management in the USA about USA earthworm trials. Not all products are sadly available legally in the UK.
The search continues. Email the CastClear Team