SCOTLAND, UK - The most recent survey by Scotland’s Rural College (SRUC) indicates that after two years of record numbers, Leatherjacket densities have plummeted.
Leatherjacket is the name given to the grubs of the crane fly or 'daddy-long-legs' that live just below the soil surface. From August through to the following June the grubs eat the roots of grasses and other plants.
However, while the falling densities reduce the need for any chemical controls, SRUC experts urge farmers with spring crops planted after grass to monitor growth carefully and to check their soils for signs of the grubs.
Professor Davy McCracken, the SRUC Ecologist who led the survey, said: “The fact that it is such a low risk year makes it even more important to conduct an assessment of any fields where the growth of crops sown after grass may be of concern.
“This will confirm if there is a problem and what the culprit is. Chemical controls, which are costly and have an environmental impact, should only be used where necessary.”
The only permitted insecticide effective against Leatherjackets on agricultural land is chlorpyrifos. It is a chemical constantly under scrutiny by EU experts as they consider whether to permit its continued use beyond January 2018.
Professor McCracken advised: “If control measures are recommended for a particular field then whoever is applying them should remember the need to abide by 'Stewardship' measures for chlorpyrifos applications.
“When applying chlorpyrifos for leatherjacket control only fit LERAP rated 3 star nozzles to the sprayer and establish a no-spray buffer zone within 20 metres of watercourses or within 1 metre of dry ditches.
“This advice is a key part of the Stewardship ‘Say NO to drift’ initiative which aims to support the future availability and use of insecticides containing chlorpyrifos.”
SRUC research has been conducted since the mid 1970’s and offer a long term analysis of Leatherjacket populations.
While they can put crops at risk Leatherjackets are an important food source for some farmland birds and these latest results suggest there will be less food for them this bre
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