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Efficacy trials of OMRI approved materials on vegetable crops

Cabbage aphid

Cabbage aphid is a pest that has been reported to build up late in the season on kale and other fall crucifers, especially after the first frosts. The aphids may be more frost-tolerant than their natural enemies. The aphids are covered with a white waxy exudate, which protects them to some extent from insecticides, and their feeding can cause leaf distortion. In any case, greens infested with cabbage aphids are not marketable.

Broccoli transplants were grown in six inch pots until they reached the 6-leaf stage and were then placed in cages into which field collected cabbage leaf aphids were released, and allowed to colonize and acclimate. The plants were removed from the cages to be treated, returned to the cage, and evaluated after seven days by counting the number of live aphids. After evaluation, an additional application was applied to treatments that still had living aphids, and again evaluated after 7 days.

Mean # aphids/leaf

Treatment Rate/A 10/2 10/9

Surround WP

15 lb.

21.9 a

8.0 a

Rotenone 5%

3 lb.

24.3 ab

12.3 a

Ecozin

8.0 oz.

29.9 ab

14.3 ab

Naturalis L

16 oz.

33.9 b

21.0 b

Control

 

75.9 c

86.4 c

Values followed by the same letter are not significantly different

All of the treatments significantly reduced the aphid populations compared with the controls, but this level of reduction may not be enough to make the crop marketable. The two treatments with the best control are the least attractive in terms of potential residue. The Surround product leaves a significant visible residue on the plants, which may render them unmarketable, and cool fall conditions may delay the breakdown of the Rotenone residue.