Leatherjackets can be a serious lawn pest especially in poorly drained lawns and after a wet autumn. In late summer Crane flies, better known as daddy-long-legs, lay eggs in the grass and clouds of the daddy-long-legs can be seen leaving the lawn afterwards early in the morning. It is the grubs (pictured above) that hatch out in autumn that cause the damage. They feed on roots and stem bases in spring causing yellow and brown patches in your lawn and causing the lawn to have little root growth.
Secondary damage can be caused by starlings, foxes and badgers as they try to eat the grubs. A way of detecting the problem is to water a patch of lawn and then lay a piece of black polythene over the grass overnight. In the morning the inch long brown or grey grubs should be visible.
But fear not as their is a natural way to control this pest that is compatible with organic gardening. The prolific lawn pest is hunted down and killed by the nematode steinernema feltiae contained in Nemasys Leatherjacket Killer but there is only a small window of opportunity to prevent this lawn damage; Nemasys Leatherjacket Killer applications should be made 1 – 2 weeks after the first craneflies have been spotted usually from August onwards. The nematodes should be applied from late August to the end of October. Application of the nematodes can save you a lot of money in comparison to re-turfing the lawn.
The product can simply be watered onto the lawn using a watering can and a coarse rose, but full instructions are provided. Two sizes are available. One to treat 100 square metres and the other to treat 500 square metres. The lawn must be kept moist before and after application for at least two weeks. This is important as if the grass is allowed to dry out too much the nematodes may die. The Nemasys nematodes are safe to use around children, wildlife and pets. Soil temperatures should be above 12 degrees centigrade or 54 degrees Fahrenheit for the treatment to be effective. Do not worry about the fact that the nematodes are living creatures. They are so minute that they will be undetectable. The product is only available from retailers at the correct time for application.
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Mark Snelling
All images copyright Harrod Horticultural
