| Abstrakt: |
Insecticides and schedules of application were evaluated in Iowa for the control of the cabbage leaf-feeding complex of the diamondback moth, Plutella maculipennis (Curt.), the imported cabbage worm, Pieris rapae (L.), and the cabbage looper, Trichoplusia in (Hbn.), infesting cabbage grown for fresh market sales in July. Relative amounts of leaf damage caused by the combined feeding of these insects was visually rated in five classes. The data obtained were suited to statistical analysis. The method of evaluation was economical of time. Endrin, 0.25 pound per acre, was superior to other compounds tested. Guthion, parathion and Thiodan at 0.75, 0.33 and 0.50 pound per acre, respectively, were superior to DDT, 1 pound per acre. Endrin and parathion at 0.3 pound per acre applied weekly were equally and extremely effective. Phosdrin, 0.3 pound per acre, was nearly as good as endrin, Biweekly applications of DDT, 1 pound per acre, were inferior to weekly applications of DDT at the same rate, or to toxaphene, 2 pounds per acre, and to parathion applied weekly or biweekly. Methoxychlor, 2 pounds per acre, frequently recommended in the North Central States, was of little value in preventing the leaf damage. |
