Effect of Insecticide Fertilizer Mixtures and Seed Treatments on Emergence of Sugar Beet Seedlings1

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Abstract
Two years’ results in Manitoba have shown that heptachlorfertilizer mixtures, applied to the seed furrow for control of the sugar-beet root maggot, Tetanops myopaeformis (Roed.), did not reduce sugar beet stands significantly. phototoxic effects were not serious, even under dry soil conditions, when fertilizer mixtures (consisting of 1.25,% actual heptachlor, 1.8% to 5.0% xylene on ammonium phosphate (11-48-0)) were applied to the seed furrow at 80 pounds per acre. The phytotoxic effect of insecticide fertilizer was attributed to fertilizer which interferes with the uptake of the water required by the seed for germination mixtures, or to insecticide or solvent which may cause seedling damage. Phorate and Diazinon® ( O, O -diethyl O -(2-isopropyl-propyl-1-4methy1-6-pyrimidinyl) phosphorothioate) were more phytotoxic than Trithion® ( S-(p -chlorophenylthio)methyl O, O - diethyl phosphorodithioate) or heptachlor in field and laboratory tests. Similarly the insecticide solvent Velsicol AR-60 shown by this laboratory test to be more phototoxic than xylene depressed seedling emergence significantly in the field. Laboratory tests showed that when soil moisture was 21% or 16.6%, seedling emergence was reduced significantly when heptaehlorfertilizer mixtures or fertilizer were applied in contact with the seed. But the addition of heptachlor and 2% solvent did not depress emergence more than fertilizer alone. Seed treatments with heptachlor and Trithion or phorate and Diazinon were not phytotoxic when used in conjunction with captan-treated seed. Without captan, heptachlor and phorate depressed seedling emergence, but heptachlor in combination with captan may enhance the protective action of captan. Captan-treated seed improved seedling stands slightly when used with heptaehlorfertilizer mixture.