Greenkeeper News: Leather Jacket Activity

For the past week we have encountered an increase in leather jacket activity, a leather jacket is the larvae of a crane fly. Each fly can lay up to 400 eggs, they typically lay their eggs in manicured areas as they have a food source to survive the winter. October is a critical month for laying eggs and they will use aeration marks to lay their eggs into the profile of the soil. Eggs are then washed deeper into the profile from heavy rainfall. Eggs begin to hatch in December; a hard frost usually terminates thousands of eggs however we experienced a mild winter this year and the majority of the larvae survived. This is a nationwide issue and lots of golf clubs are sharing information, national governing bodies are also communicating on best practises and guidance on mitigating the issue.

The next key phase of their development comes in spring, they have matured into mobile larvae and travel within the soil profile in search of food, they will feed of roots in the greens, we typically experience yellow patches on the greens, and the yellow effect is a result of the sward being stressed. Usually the sward will make a full recovery as ground temperatures stimulate root growth. This spring has been cold and dry and we are yet to experience sufficient ground temperatures to promote growth and recovery. Some of our trees are yet to develop leaves, this is an indication how challenging the environment is to grow fine grasses mown at low heights of cut. The birds have pecked some of the greens and left marks on the playing surface, I appreciate this is effecting the playing experience; I can honestly say we have worked hard behind the scenes to combat this issue, were passionate about creating a playing surface that’s true. We are trying to fill the bird pecks with top dressing to create this true surface. We have prepared for several competitions this week whilst trying to repair the greens; it’s been challenging but we are controlling the problem. In previous years we had chemicals at our disposal that would eliminate the issue with one application, however since 2006 over 2,000 chemicals we could utilise for amenity use have been withdrawn from service. We now have to adopt more cultural practise for managing fine turf, from an environmental impact it’s imperative we adopt safe working practises, it may be more labour intensive but these chemicals are banned for a reason.

On Monday night we covered the putting green with a silage sheet and removed the following morning, under the sheet was thousands of leather jackets that we could safely remove with our rotary brushes. The method of sheeting is highly effective but labour intensive; the humidity underneath the sheet draws the larvae to the surface, where we can collect and dispose of the larvae in a safe environment. Several of our committed volunteers are coming in nightly to cover the greens with our sheets. If you interested in helping late one evening please get in touch so it’s not a burden on the same people, it’s a low to moderate physical task and takes 10-15 mins per green.