| Abstract: | A two-season trial of a mist blower-sprayer with improved air-flow characteristics was made to assess the relative efficiency of 120 and 180 μm mass median diameter (MMD) drop-size sprays for the control of apple powdery mildew (Podosphaera leucotricha) and fruit tree red spider mite (Panonychus ulmi Koch) in a hedgerow-type apple orchard. The principal pesticide was binapacryl, applied at two rates for each drop-size. Under typical commercial conditions the smaller drop-size approximately halved the incidence of apple mildew found when the conventional 180 μm MMD drop-size spray was used; there was no conclusive advantage against red spider mite. Unexpectedly large variations occurred in the deposits from the weekly applications and were related to the humidity during spraying. |
