No, Dogwoods don‟t get tired of looking at other trees and shrubs in your land-scape! I‟m talking about dogwood „borers,‟ Synanthedon scitula. These are the most destructive insect pests that attack flowering dogwood, Cornus florida in Ten-nessee. Wounded trees are the most vul-nerable since the larva gain access through wounds or scars. The adult is a clearwing moth that looks like a wasp. An early symptom is sloughing of loose bark from areas that have been attacked. More ad-vanced symptoms are crown dieback and adventitious shoot growth along the trunk and scaffold branches.

The adult moth is about 1/2” long and has a blue-black body with yellow bands and clear wings. It generally begins to emerge in late April to early May. The females lay eggs on or near wounds or in the crotches of scaffold branches. The larva feed on the cambium and remain in their tunnels throughout their develop-ment. The larva overwinters in the feed-ing tunnel and begins feeding again for a short time in the spring before pupating. There is usually only one generation per year.

The following measures can be taken to manage this pest:

1) Prune out and destroy infected branches.

2) Avoid unnecessary wounding, i.e., string trimmer damage to the base of the tree.

3) Preventive spray applications of per-metherin should be applied to the trunk, root collar and main branches during late April and mid-July.

4) Promote the vitality of the tree by maintaining soil fertility and applying water during dry periods.

Following this plant health care regime should give you many years of enjoyment from your flowering dogwoods.■

Kim Cross

{ 0 comments }