Author: HASEMAN, L.

Source: Journal of Economic Entomology, Volume 16, Number 3, June 1923 , pp. 270>-275(6)

Publisher: Entomological Society of America

Abstract:

The original purpose of this investigation was to determine what type of spray nozzle and what pressure places the greatest quantity of arsenic in the lower calyx cup of apple blossoms for the control of the codling moth, Carpocapsa pomonella. The spray tests are made immediately following the dropping of the petals by using usually three nozzles each with three pressures. To determine the calyx content of arsenic a counted number of the small apples are collected from each of the test trees and the lower calyx cups with their arsenical content are carefully removed for chemical analysis. In this way it has been possible to determine the average arsenical content of the calyx cup of each apple from trees treated with different pressures and nozzles. These experiments show that a high pressure and coarse nozzle is less effective than a lower pressure with a nozzle throwing a finer mist. They also show that where the average calyx content of arsenic is the highest the percentage of calyx worms in picked apples is not always the lowest.

After determining the average quantity of arsenic placed in the calyx cups under good orchard management, the investigation was enlarged in order to determine whether or not this quantity of arsenic is sufficient to poison apple worms attempting to enter at the calyx end of the fruit. This called for careful laboratory tests to determine the lethal dosage for apple worms. Doses of powdered arsenate of lead varying from one millionth to five ten thousandths of a gram were fed to apple worms of varying stages of development. To administer these small doses one or more drops of distilled water with the dose in suspension were placed on bits of apple which the worms consumed. These experiments show that for third instar apple worms and older ones, the lethal dosage is approximately five ten thousandths (.0005) of a gram of powdered arsenate of lead. This is practically the same as the average calyx cup content (.000521 grams) as shown from numerous orchard spray tests. It seems certain therefore that in good orchard spraying the lower calyx cup of each blossom hit squarely with the "Calyx Spray" will receive sufficient arsenic to poison the small apple worms which may attempt to enter the fruit at that point.

Document Type: Research article

Publication date: 1923-06-01

More about this publication?

• Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.
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