Description:
A granular controlled release formulation of 2 percent MCH was applied at 4.48
kg/ha to 76.9 ha of uninfested, windthrown Douglas-fir by helicopter with a
modified aerial spreader of 1.12 m capacity in May 1982. Douglas-fir beetle
population reduction was 96.4 percent by late June. With one exception,
treated plots had no successful attacks through 1984. Successfully attacked
trees in stands surrounding treated plots declined sharply by the second
season. This may indicate MCH dispersed beetles over a wide area preventing
the development of many epicenters. Mortality remained high in check areas and
surrounding stands. In all areas surrounding treated blocks and check areas,
the number of pitchouts increased and average diameter of successfully attacked
trees declined with successive years of infestation. This pattern is
indicative to that experienced following a beetle population buildup in
windthrow in other areas. We recommend MCH be registered at 2 percent
controlled release formulation for application to inaccessible windthrown
trees, and to protect adjacent high-value stands.