Effect of Insecticides on Emergence of Sugar-Beet Seedlings and on Control of the Sugar-Beet Root Maggot

Both heptachlor-impregnated triple superphosphate (0-43-0) and heptaehlor-impregnated ammonium phosphate (11-48-0) at 1 lb. of toxicant per acre significantly reduced damage by the sugar-beet root maggot, Teta/wps myopaeformis (ROder). Ethion (Niagara Brand Spray Company Limited) at ] lb. per acre, Trithion®( O,O -diethyl S(p-ehlorophenylthio)methyl phosphorodithioate (Stauffer Chemical Company, Portland, Oregon)) at lib. per acre and seed treatments with heptachlor at both] and 2 oz. per acre also reduced maggot damage. The heptachlor-impregnated ammonium phosphate at 1 lb. of toxicant per acre a seed treatment with heptachlor at 4 oz. per acre, and Bayer 29493 ( O,O -dimethyl O -[4-(methylthio)-m-tolyl] phosphorothioate (Chemagro Corporation, Kansas City, Mo.)) at 1 Ib. per acre significantly reduced emergence of seedlings, and the latter treatment gave little control of the maggot. The sugarbeet root maggot was most effectively controlled in southern Alberta with 1 lb. of heptachlor per acre placed in the drill row with the seed or 3 Ib. per acre of heptachlor placed in a 5-inch hand over the row. These two treatments, however, left residues of heptachlor and heptachlor epoxide in the sugar-beet roots at harvest.