Abstract
Dosage, volume, and timing experiments with concentrated DDT sprays were carried out against the European pine shoot moth ( Rhyacionia buoliana (Schiffermuller)) in red pine ( Pinus resionosa Ait .) plantations in Michigan from 1956 to 1958. Concentrated sprays were applied by several types of mistblowers, as well as by fixed-wing aircraft. Simulated concentrated sprays were applied by backpack sprayers. The least DDT dosage in mistblower treatments consistently giving 90% or greater population reduction was 10 pounds of actual toxicant per acre; the least volume, 40 gallons of water spray per acre. Under some conditions, less DDT dosage and volume seemed to suffice. Oil sprays in summer at rates of 10 or more gallons per acre caused foliage browning. The period available for applying concentrated sprays to achieve 90% or greater reduction in population in the spring is 2 weeks or less, depending on dosage, in contrast to the 4 weeks available for applying diluted sprays.
Published Version
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