Control of Wireworms on Potatoes in Eastern Washington by Soil Fumigants and Organophosphorous Insecticides123

Abstract

Soil fumigation with Telone® (mixed dichloropropenes), DD® Mixture (dichloropropanc-dichloropropene mixture), and ethylene dibromide, applied at 20 gal, 25 gal, and 36 lb/acre, respectively, and broadcast applications of granulated diazinon, parathion, and phorate, applied at 2, 4, and 3 lb/acre respectively, gave economic control of the Pacific Coast wireworm ( Limonius canus LeConte) on potatoes in sandy loam soil. Cullage was reduced 93.6-100%. Granulated disulfoton, broadcast at 3 lb/acre, gave significantly less control than other broadcast treatments. Post-planting sidedressings of granulated parathion, phorate, Stauffer N-2790 ( O -ethyl S-phenyl ethylphosphonodithioate), and Bayer 25141 [ O-O -diethyl O-p -(methylsulrfinyl)phenyl phosphorothioate), applied at 3 lb/acre, reduced cullage 74.4-85.2%. Granulated disulfoton and Bayer 37289 ( O -ethyl 0-2,4,5-trichlorophenyl ethylphosphonothioate) at 3 lb and naphthalene crystals at 450 lb/acre were significantly inferior to the other sidedress treatments. Phorate and disulfoton granules gave as good control when metered onto the soil surface in bands 6 in, wide in the furrow left by the press-wheel potato planter as when side dressed in the soil at the same rate. Of all diazinon, disulfoton, parathion, and phorate treatments, only phorate applied in the planter press-wheel furrow left a detectable residue above the tolerance in tubers collected 3 weeks before harvest.