On a selection of randomly selected fields across four Fermanagh farms taking part in an AgriSearch-led project looking at leatherjacket control, around a third had populations above a threshold likely to cause significant yield loss.

Explaining the results at a recent webinar, Dr Archie Murchie from AFBI said leatherjacket populations of over 0.5m/ha are likely to hit grass yields by around 0.5t dry matter/ha. Leatherkjackets, which are the larvae of crane flies (daddy longlegs), feed on grass roots. They were traditionally controlled using Dursban (chlorpyrifos), but it has been banned since 2016. The aim of the AgriSearch project is to identify other potential strategies to mitigate against the problem.

According to Murchie there is “some anecdotal evidence” that grazing out swards in the autumn will reduce the risk as the crane fly likes to lay eggs among long grass.

The insect is also thought to prefer laying eggs in waterlogged soils, may not thrive as well in recently limed soils, and populations are likely to be significantly reduced when land is ploughed. Teagasc research has also shown that various herbs in mixed-species swards seem to have a high tolerance to Leatherjackets.

“We are looking at a multi-season, long-term management approach to mitigate the population levels. We are hoping to convey a best-practice model,” confirmed Murchie.

The AgriSearch study will conclude in June 2023.

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