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Dogwood Borer Infestation in NJ Apple Orchards

Reprinted from the Rutgers Cooperative Extension Plant & Pest Advisory Fruit Edition
Vol. 4 No. 11, June 15, 1999, p. 5-6

Win Cowgill, County Agricultural Agent
Dean Polk, Statewide IPM Fruit Agent

With the introduction of higher density apple orchards and the utilization of dwarfing clonal
rootstocks, the dogwood borer has been observed in New Jersey apple orchards. The dogwood borer
(Synanthedon scitula), was discovered for the first time in the Northeast in the 1980's. They have been
observed as a problem in Virginia, West Virginia, Maryland, New York and Michigan Apple

Untreated infestations of dogwood borers may reduce yields and in rare cases girdle young trees. The
infestation occurs primarily in burr knots and at the graft union in callus tissue on the more dwarfing
clonal dwarfing rootstocks. Burr knots are root initials that most often appear on the shanks of
exposed rootstocks, such as the M9 clones, M26, M7 and especially MARK. Growers also should be
aware of burrknot producing scion cultivars such as Empire and Gala.

Cultural control should consist of keeping the trunk area weed free so moisture does not remain any
longer than necessary. Tree guards also provide an ideal growth environment for burr knots and
prevent pesticide applications from reaching the trunks. The use of white latex paint on the trunks is
also effective in helping to prevent the infestation of burr knots with dogwood borer. We utilize a
mixture of 50% white latex paint with a low acrylic content mixed with 50% water. This makes a white
wash that can be sprayed on the trunks and rootstock shanks. It assists in the prevention of southwest
injury as well.

In 1998 at the Rutgers University Snyder Research and Extension Farm in Pittstown, NJ, nine year
old Empire trees on M26 rootstock were found to have nearly 100% infestation of dogwood borer
larvae in the scion and rootstock produced burrknots. Up to 6 larvae per burrknot were found in some
of the trees. The trunks of the trees are guarded with solid plastic tree guards, aiding in a favorable
environment for the formation of burrknots and reducing the amount of pesticide reaching them.

For chemical control, Lorsban 50W has a label for dogwood borer on apples This is a Gowan product.
The label rate lists 3 lb./A of Lorsban 50 W. However, for effective dogwood borer control the
application should be made with a handgun soaking the tree trunks and burr knots with the solution
and puddling the solution at the base. Utilize the 3lb/A rate in 100 gallons of water. Penn State says 6
oz per tree with a backpack sprayer directed at the burr knots and the surrounding tissue is effective.
Do not exceed the 3lbs/100gallons per acre rate.

Yes there are pheromones available and they can be trapped. We will be placing dogwood borer traps
at selected locations in NJ apple orchards. The pesticide application
Should be made just after peak flight. In NJ most of our borer activity is
from late July into August.

For more information on dogwood borers visit the Penn State Web Site at

obtain the Cornell Fact Sheet on Dogwood Borer at:

Or the West Virginia website at

1999 North Jersey Tree Fruit Annual Report