Tuesday, August 19, 2008

Greenhouse - Caterpillars on Ornamental Cabbage and Kale

Caterpillars need to be controlled on ornamental cabbage and kale. Several caterpillars will attack these plants this time of year, but the most common is the Imported Cabbage Worm. The following is some information.

The familiar imported cabbage worms adults can be seen fluttering above ornamental cabbage and kale. The adult is a white butterfly tinged with yellow on the underside of its wings.

Females have two black spots on their wings, but males have only one black spot. Look on the upper leaf surface for the bullet shaped eggs with fine parallel lines. Eggs hatch into slow moving velvety-green larvae that is easily missed as it blends into the green leaf color. Larger caterpillars have a delicate yellow line that runs lengthwise down the center of their bodies. Look for the larvae and signs of their feeding damage (irregular holes in the leaves, and dark green droppings) on ornamental kale and cabbage.

Many different materials are labeled including various formulations of Bacillus thuringiensis B. T) var. kurstaki (Biobit HP, Deliver, Dipel Pro DF, or Javelin WG) can be used against the small actively feeding caterpillars. Conserve is also labeled for many lepidoptera larvae including the imported cabbageworm. Many pyrethroids, Orthene, and Spintor are also effective and may be preferred when large worms are found.

Information taken in part from the New England Greenhouse Update.

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