At the the start of the year I visited golf course that was about to close due to turf damage caused by pests living under the soil. The pests – and the damage – had spread across the grass area, eating and destroying every blade of grass in their wake. This scenario is a nightmare for professionals working in
turf and amenities, but it can be avoided if groundscare teams understand the causes and the steps that can be taken to overcome the problem.
What causes damage to turf?
The most common pests causing this type of damage are chafer grubs and leatherjackets. Chafer grubs
are the soil-dwelling larvae of chafer beetles and leatherjackets are the larvae of the crane fly (daddy long legs). Both types of larvae feed on the roots of grass plants, killing the grasses and leaving large areas of turf stripped of green. Crows, badgers and other wildlife can also add to the problem by digging up the soil to eat the larvae, further stripping the turf.
The leatherjacket larvae & crane fly
Until recently, turf and amenity managers were able to control these insect pests with chemical pesticides – it was even common to spray undamaged turf with these products to prevent any infestations. However, due to their toxicity, those chemical pesticides are no longer available, and the chafer grubs and leatherjackets are enjoying a chemical-free playground that is allowing them to flourish in soils. They are now destroying golf courses, sport fields, racecourses and the general landscape, causing millions of pounds of damage annually.
How can it be stopped?
Biopesticides are filling the gap in the market left by banned chemical pesticides. Biopesticide technology developers – such as Bionema – harness nature by identifying and developing products that use natural enemies to manage insect pests in different sectors. Probably the best known example of a ‘biopesticide’ is the ladybird – gardeners who encourage ladybirds to flourish are less likely to be bothered by aphids.
Unfortunately, ladybirds won’t attack chafer grubs or leatherjackets, but other ‘friendly’ organisms will. Certain species of beneficial nematodes (roundworms) will actively search for insect larvae in the soil. They enter the larvae through natural openings and release bacteria that are lethal to the larvae, killing them within two to three days.
The nematodes breed within the dead larvae, feeding on the body tissues. They reproduce within two weeks and emerge in search of more larvae, and so the natural cycle continues. This self-sustainability offers extended pest control and helps to ensure that overall costs compare favourably with those of old chemical pesticides.
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