Occasionally in certain seasons of the
year, other pests may cause our trees to be significantly
stressed. Some even cause the tree to have the appearance of
having oak wilt. These pests may be animal, insect, or another
disease organism.
web worms
Because web worms are seldom
life threatening to trees and because insecticide spraying
is costly and seldom effective on web worms, the City does
not spray pesticides to control them. We are now
experiencing the second generation of web worms this summer
and should see one more this fall. They can completely
defoliate a tree, but unless it is already under severe
stress, it will leaf back out when they are gone. Healthy
trees are more than capable of tolerating two or three
defoliations in a growing season.
Breaking the webs open in the
early morning will make the worms more vulnerable to morning
feeding birds and other predators. If a tree is already
under stress and pesticide application is necessary
this link to an Agricultural Extension Service bulletin
on practical control methods for webworm may be helpful.
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