Replicated plot tests were conducted by applying technical malathion (95%) at ultra low volume (8 fl oz per acre) against grasshoppers on rangeland from Cessna® 337 aircraft. When fine (volume-median-diameter (vmd) of 135 µ.) and coarse (vmd, 278 µ.) sprays were applied from different heights, fine spray from 200 ft was significantly inferior to coarse spray in the degree of control produced. No significant difference was apparent between treatments with fine spray from 50 or 100 ft and with coarse spray from 100 and 200 ft. The experiments indi-cate malathion is the most efficient against grasshoppers when delivered in a moderately coarse spray cloud and flight height does not exceed 100ft. When 0.1 inch of moisture was applied to plots immediately before and at 2 and 8 hours after treatment with malathion, no significant effect on treatment was apparent. These results were substantiated by the observed effects of natural rainfall and dew. However, experience in the field has shown that rainfall can be detrimental to control with malathion.
Document Type: Research Article
Publication date: August 1, 1968
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