Control Tests Against the Two-Spotted Spider Mite, Tetranychus telarius (L.), on Strawberries1

Abstract

The two-spotted spider mite, Tetranychus telarius (L.) (= T. urticae (Koch)), although a problem on strawberries throughout New York, is particularly severe in the Hudson valley and Long Island area. Early-season control is essential for protection through the limited harvest period of June-bearing strawberry varieties. Perhaps owing to the variety of spray programs used in the past, no pronounced resistance has developed to the organophosphorous materials as a group. Of the organophosphorous materials tested, phorate provided the most effective control. Very good control was obtained with carbophenothion, particularly when used at a rate of 1.0 pound actual. Tepp, azinphosmethyl, and Niagara 9203 ( O,O dimethyl S -[(2-oxo-3-benzoxazolinyl) methyl] phosphorothioate) gave some control but had limited residual effectiveness. Of 32 materials tested, dicofol was consistently one of the superior materials for the control of this pest. Another chlorinated hydrocarbon. Dimite® (4,4'-dichloro- alpha -methylbenzhydrol), had limited residual effectiveness while Chloropropylate® (isopropyl 4,4-dichlorobenzilatc) was ineffective. Morestan® (6-methyl-2,3-quinoxalinedithiol cyclic carbonate) gave particularly good control in 2 applications at 0.25 pound actual. This material resulted in plant injury following some applications but not others. The carbamate Bayer 37344 (4- (methylthio) -3,5-xylyl methylcarbamate) provided fair control against recently hatched mites. A second carbamate, Union Carbide 20047A [5-chloro-6-oxo- endo -2-norbornanecarbonitrile O- (methyl-carbamoyl) oxime], appeared particularly promising. Tetradifon (miscible) and tetrasul ( p -chlorophenyl 2,4,5-trichlorophenyl sulfide) were unsatisfactory while OW-9 (2-[2-( p-tert -butylphenoxy) -1 -methylcthoxy]-1-methylethyl 2-chloroethyl sulfite) provided fair control. Fair control was obtained also with Hoechst 2836 (binapacryl and a halogenated urea derivative), binapacryl, and Union Carbide 19786 (2- sec -butyl-4,6-dinitrophcnyl isopropyl carbonate).