Newspaper article St Louis Post-Dispatch (MO)

Remedies for Treating Borers on Dogwood

Newspaper article St Louis Post-Dispatch (MO)

Remedies for Treating Borers on Dogwood

Article excerpt

Q * Last year my flowering dogwood tree became infested with borers. I was advised to spray the tree with an insecticide. Not wanting to go that route, I decided to scrape away the infected places and treat the wound with a tobacco-salve mixture of my own devising. I also wrapped the wound and placed a circle of moth balls at the base. The tree did bloom and leaf out this spring although not as fully as it should. Is there anything else I can do for the tree without using insecticides? Also, would fertilizer help?

A * Several different borers can infest dogwoods. Two of the most common are the flatheaded apple tree borer, which is the larva of a beetle, and the dogwood borer, which is the larva of a moth. The flatheaded apple tree borer normally emerges in May, but egg-laying may continue through summer into early fall. The dogwood borer normally emerges several weeks later in June, but egg-laying can also continue until fall.

As far as your remedies are concerned, they may be helpful in some instances, but harmful in others. Wherever there is loose bark, it should be carefully removed, but only back as far as sound wood. It is important not to inflict additional injury on the tree. Wounds provide an easy entrance point for dogwood borers. In some instances, probing the holes and tunnels created by borers with a thin wire may kill the insect in place and minimize injury, but it's a hit-and-miss proposition.

Tobacco products can be a source of nicotine, which was used for many years because it is a broad-spectrum poison to many insects. With your "home brew," it's anybody's guess as to its strength, effectiveness or even safety. Commercial nicotine products are now restricted-use pesticides in the state of Missouri because of their acute toxicity.

Tree wraps have been shown to be effective in preventing egg- laying by the flatheaded apple tree borer on the bark of newly planted trees. …

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