2009-06-09_PR Comm Packet - Laserfiche WebLink

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Spring and Fall CankerwormsPage 3of 3 b.Examining foliage of several trees for the first signs of young cankerworms or their feeding. 2.Add 10 days to the date of hatch as determined in step one. This will be the best date for spraying. 3.Examine representative trees during the 10-day post-hatch period to determine if development has slowed or quickened because of weather conditions. 4.Modify the spray date as necessary, keeping in mind that the worms should be less than 1/2 inch in length and that at least 50% of the leaf surface should be intact. 5.Spray with one of the suggested materials. Trunk Banding -- One widely-known method of treating cankerworms is the use of sticky barriers applied to tree trunks. As the wingless females crawl up the trunk to lay eggs, they are trapped in these sticky bands. Despite the publicity, there is little evidence that this method is worthwhile even in areas where most trees have been banded. The possible exception would be on a tree that is isolated from other cankerworm-susceptible trees. Although the practice is fine in theory, it generally fails because of one or more of the following reasons: (1) people do not clean and renew the sticky material as often as the bands become crowded with moths; (2) people fail to recognize and band for the two species (one moving up the tree in the fall, the other in the spring); (3) unbanded trees in an area may produce young cankerworms that can readily blow to banded trees on silk threads. Furthermore, the sticky material is expensive, messy to work with, and tends to mar the appearance of the trunk for a long time. Thus, banding is not recommended. Mark Ascerno, Head Entomology Jeffrey Hahn, Professor, Entomology Department of Entomology College of Agricultural, Food and Environmental Sciences http://www.extension.umn.edu/distribution/horticulture/DG0876.html6/5/2009