Abstract
The balsam twig aphid, Mindarus abietinus Koch, attacked A. grandis (Douglas) Lindley and A. concolor (Gordon and Glend.) Lindley and caused severe stunting, needle fall, and twig distortion of Christmas trees in westem Washington. Ultra-low-volume application of 0.25 g oxydemetonmethyl per 4- to 6-ft-tall tree gave effective seasonal control. Oxydemetonmethyl, dimethoate, and Azodrin® (3-hydroxy-N-methyl- cis -crotonamide dimethyl phosphate) applied to the trunk at 2.5 g per tree in water alone or with the adjuvants Estab® (Velsicol Chemical Co.) or Roplex® (Rohm &Haas Co.) gave excellent control, but this high rate and application expense is economically impractical except for high-value trees.
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