Fall is the time to prevent cankerworms and spring defoliation |
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The fall cankerworm (commonly called inchworms) has become a growing nuisance to trees and property owners over the last few years. Feeding larvae can defoliate and build bothersome webs in many tree species. Usually, willow oaks are targeted, but other tree species from dogwoods to maples can be affected.
After many years of infesting trees in Charlotte, cankerworms moved into Harrisburg in 2009 and made their way to Concord and Kannapolis in 2010. Cabarrus cankerworm populations continued to increase in 2011 and 2012. Remember:
- Cankerworms won’t last forever. Past experience in Cabarrus County indicates the larva stage will be present only about 4 to 5 weeks from the time they hatch out in early spring.
- Fall cankerworms will not kill a healthy tree in their spring feeding frenzy. If all the leaves are removed, the tree will wait a few weeks and then put out new leaves. After new leaves form, there still will be enough growing season for a healthy tree to recover.
- The best control for reducing future infestations is tree banding. Place bands on trees in November and monitor them until the larva disappear in April.
- Spraying is less effective. Since the larva stage is short term, the cankerworms won’t kill the tree and spraying a mature tree is difficult or expensive. Most homeowners will ignore the spring infestation on mature shade trees.
- If you wish to control fall cankerworms on understory shrubbery during the spring larva stage, any pesticide that controls caterpillars will work on fall cankerworms.
Because the female moths climb trees following the first freeze in the fall to lay eggs, using the tree banding technique at that time can help control this growing problem. Eggs hatch in the spring, then defoliate and weaken trees. Banding trees in mid-November and smearing the bands with a sticky substance prevents the female wingless moths from climbing up the trunks to lay eggs in the tops of the trees.
The public is invited to hear a presentation from local cankerworm expert Jack McNeary at 10:00 a.m. on Tuesday, October 2 at the Cabarrus County Cooperative Extension Center, located at 714 Cabarrus Avenue West in Concord. Several demonstration trees have been banded along Union Street North and the McEachern Greenway for residents to see examples.
For more information about cankerworm prevention and tree banding instructions, click here.