Risk of insect pest attack reaches new high According to surveys carried out by Dow AgroSciences the population of leatherjackets recorded in the midlands and northern areas has achieved the highest levels since 1991. The results indicate an overall high risk of damage to susceptible crops after grass. Leatherjackets are the larva of Crane Flies (Daddy Longlegs). They are soil inhabiting, up to 5cm in length with thick grey-brown skin and feed on the roots and stems of susceptible plants at or below ground level.

The population threshold at which control becomes economic varies with crop type:

Sugar beet and other row crops ~ 25 leatherjackets / m2
Spring cereals~ 50 leatherjackets / m2
Permanent pasture~ 100 leatherjackets / m2

The average leatherjacket population in the region is very high this year at 190.3/m2, compared to 70.3/m2 last year and 13.1/m2 the previous year. Of the total number of fields sampled 81% had a population greater than 50/m2.

Action
The risk of economic damage from leatherjackets this season is significantly high than in recent years. Fields with a history of leatherjacket damage should be monitored. Large numbers of rooks and crows feeding would give an indication, risk assessment and testing for the presence of leatherjacket larvae will identify fields that are most likely to need treatment. If treatment is required apply Dursban* WG at 1.0kg/ha.

*Always read the label. Use pesticides safely. Dursban WG contains chlopyrifos. Dursban is a trademark of Dow AgroSciences LLC

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