Orange wheat blossom midge: Survey of the 1994 outbreak

Abstract

Examination of the 1994 HGCA Cereals Quality Survey samples has shown that levels of grain damage due to larvae of the orange wheat blossom midge (Sitodiplosis mosellana) were down overall in the areas of eastern and southern England where sprays were applied most intensively in 1994, but up nearly everywhere else. Nationally 9% of samples were above the yield loss threshold level of 10% and a further 28% of samples above the potential quality loss threshold of 5% grain damage. In areas where effective spray action was not taken damage had increased by about 50% on 1993 levels. The incidence of apparently missed crops within the eastern counties suggests that a similar increase would have taken place there but for the action taken. The loss to the UK crop is estimated as £20 million compared to £30 million in 1993. Spray action costing £6 million reduced the loss from a potential £50 million, giving a 1:5 cost:benefit ratio for the control measures applied.