Excerpt from Bureau of Entomology and Plant Quarantine News Letter, 1940, Vol. 8
Conditions vere unfavorable forthe presence of bollworms, leaf worms, stink bugs, and Texas root rot in the cotton used for the tests. In view of the fact that previous investi gations had shown that arsenicals were not very effective against the pink bollworm more attention was given to fluorine insecticides and various ovi cides. The results in the plot and cage tests with insecticides were based n the percentage of reduction in larvae per boll. In the laboratory tests with ovicides, the results were based on the percentage of reduction in the number of hatchable eggs. In a Latin square with l/l6 - acre plots, comparing cryolite dusts composed of different particle sizes but approximately the same (85 - 93 sodium fluoaluminate content, micronized cryolite (kryocide) caused a reduction of percent in number of larvae per boll over the check, as compared with M6.7 percent for the regular particle size (alerco) and 25 percent for coarse particles (alerce Precipitate The coarse particle material was distinctly inferior to the others in dusting qualities and frequently clogged the hand dust guns. In three other field tests Alorco cryolite dust containing 33 percent nazan caused percent, 2m.6 percent, and hm.85percent reductions in number of larvae per boll. In a small series of cage test where the cotton plants were first treated and pink bollworn moths were then released, barium fluosilicate applied as a dust caused 81.nepercent reduction in larvae per boll, as compared vith 86.n-percent when.appliod as a concentrated.spray contai g an adhesive oil and a we ting agent. In a randomized-block experiment (three replica ticns) where six applications of insecticides were made at 5 day intervals, basic copper arsenatc dust caused 285percen reduction, cuprous cyanide dust M8 percent, cryolite dust (approximately 85 percent na2a1e6) 53 percent, and cryolite - oil spray'(5o lb. To 50 gal. Summer oil, and 50 gal. Water), 59 per cent reduction. Nicotine sulfate and light petroleum oils, alone and com bined in various proportions with and without emulsifiers, were tested in the aboratory against several thousand eggs of the pink bollworm. In part of the tests the bracts were removed fron he bells and the calyx turned back to expose the eggs, in others the eggs were either removed to blotting paper or were allowed to remain undisturbed on the bell. Bith r the evi ide was applied as a sprew or the bolls were dipped in the solution. Both the nicotine sulfate and the oils reduced somewhat the percentage of eggs hatching but in all cases were more effective when combined. In general the older eggs were more susceptible to the ovicides than the freshly laid eggs, especially in cases where nicotine sulfate was'used. Lhe percentages of reduction in hatch due to treatments, as calculated by Abbotﬂb formula, ranged from to percent. The most effective trootnent was a spray composed of two parts of mo percent nicotine sulfate to 50 gallons of miscible oil (vaporol) and 50 gallons of water. The results were encourag ing in that a high.percentage of egg mortality was obtained; however, it should be borne in mind that under ordinary field conditions incomplete coverage and other factors would doubtless influence the efficiency of the treatment.
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