Insecticidal Control of the Sugar-Beet Root Maggot and Yield of Sugar Beets1

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Abstract
Two years’ results in Manitoba have shown that heptachlor applied at 0.5 to 2 pounds per acre to the seed furrow on ammonium phosphate (11-48-0) reduced the sugar-beet root maggot, Tetanops myopaeformis (Roed.), about 80%, Some 20% of the maggots appear to tolerate this 4-fold increase in rate of heptachlor applied. This fact may represent an initial tolerance because heptachlor-fertilizers were used only 1 year prior to the tests reported. Sugar beet yields were increased 1 to 2.4 tons per acre by favoring the production of larger beets, but sugar content was not affected. However, yield was not increased when heptachlor was added at 1 pound per acre to the seed furrow as granules and side dressed with fertilizer, although effective maggot control was obtained. Dinzinon® (O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorethioate) applied at 1 pound per acre to the seed furrow on ammonium phosphate (11-48-0) effectively reduced maggots but was phytotoxie, With the same formulation and rate, phorated and Trithion®) (S-(p-chlorophenylthio) methyl O, O-diethyl phosphorodithioate) Were not effective. A direct bioassay did not detect residues of heptachlor, Diazinon, phorate or Trithion in harvested beets. Only a trace (0,01 p.p.m.) of heptachlor epoxide was detected chemically. Seed treatments with heptachlor, Diazinon, phorate and Trithion were less effective for maggot control and did not increase the yield of sugar beets.