James W. Johnson

Field and aviary evaluation of low-level application rates of methiocarb for reducing bird damage to blueberries

Abstract In the United States, Mesurol 75% wettable powder (active ingredient methiocarb) was formerly registered as a bird repellent on blueberries and cherries. In part because of concerns over residue levels, this chemical is no longer registered for use on fruit. One approach to reducing residues is to lower the application rate. Methiocarb was evaluated on blueberries in an aviary trial at application rates of 0.6, 1.1 and 1.6 kg ha−1 and in the field at 1.1 and 1.6 kg ha−1. Inthe aviary trial, individually caged cedar waxwings (Bombycilla cedrorum) were not repelled by the application at 0.6 kg ha−1, but consumption of blueberries was reduced by 60% with the treatments at 1.1 and 1.6 kg ha−1. In the field trial at 1.1 kg ha−1, bird damage to blueberries in the treated plot was 57%, compared with 29.5% on the untreated plot. In the field trial at 1.6 kg ha−1, blueberry loss at 7 and 14 days post-treatment was 59% and 85% on the treated unit and 65% and 85% on the control, respectively. Methiocarb residues on blueberries decreased from 8.56 p.p.m. at 1 day post-treatment to 1.28 p.p.m. at 14 days post-treatment. The results of these trials (a) suggest that reduced methiocarb applications do not effectively control bird damage to blueberries and (b) do not support further pursuit of a new Mesurol registration for this use.