A method of assessing losses in spring oats from frit fly (Oscinella frit (L.)) shoot attack

Abstract

Grain losses per unit area in oats following shoot attack by frit fly (Oscinella frit (L.)) were assessed in plots at Rothamsted. Individual plants were marked, and two categories of attacked plants (tillers and both main shoot plus tillers attacked) were distinguished because losses in the former were low or negligible compared with those in the latter. There was no evidence of compensatory growth for lost or damaged plants, so that losses could be assessed by comparing actual yield with yield expected had no plants been attacked. The percentage loss, weighted according to incidence and effect of attack in the two categories, was calculated from hand-harvested samples. The loss per unit area was then estimated from the actual yield obtained by combineharvesting. Estimates of actual yield were affected by the method of harvesting, so that estimates of loss were not precise.