MN Fruit & Vegetable IPM News - Vol. 4, No. 4

The dogwood borer (DWB) is a native pest of apple and other fruit crops in North America . It has only one generation in Minnesota (June-early September). In addition to DWB, the closely-related apple bark borer (ABB), Synanthedon pyri, may also occur in Minnesota orchards.

Dogwood borer (DWB) is a native pest of apple and other fruit crops in North America. It has one generation in Minnesota (June-early September). In addition to DWB, the closely-related apple bark borer (ABB), Synanthedon pyri may also occur in Minnesota orchards.

The adult DWB is black with yellow markings and clear wings. Body length is about 10
mm with a wingspan of 20 mm. In the female, the entire fourth abdominal segment is yellow, while this segment is black with a narrow yellow ring in the male. Eggs are small, oval, light brown with a hexagonal pattern of slightly raised lines. They are laid singly on tree trunks.

DWB Larvae are white to cream colored with a reddish head capsule and about 15 mm long when mature. DWB overwinter as larvae in feeding tunnels on tree trunks, resuming activity in the spring. Pupa is brown, about 10 mm long, and enclosed in a silken cocoon covered with frass. Pupal cases are found in the feeding tunnel covered with bits of frass, often remaining at the entrance of the feeding tunnel after adult emergence. Larvae feed on burr knot tissue in the trunk. This type of feeding is characterized by the presence of brown frass on the surface of infested tree trunks. DWB rarely attacks a healthy tree with smooth undamaged bark. Injury is commonly observed on size-controlled rootstocks with burrknots (aggregations of root initials) or a heavily callused graft union. This explains why damage is more common in dwarf plantings. It is easy to confuse adults and larvae of DWB and ABB. DWB has a crown of yellow hairs at the back of the head while ABB has mostly dark hairs at this spot. Also, DWB has tufts of black hairs bordered with yellow on the terminal segment, which is completely black in ABB.

In 2006, dogwood borer began showing up in traps approximately June 12th. Lures for DWB are available for monitoring adult flight.

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ACKNOWLEDGEMENTS

Co-Editors: Bill Hutchison (hutch002@umn.edu), Department of Entomology, University of Minnesota, Jeanne Ciborowski, Minnesota Department of Agriculture, Ag. Resources Management and Development Division, and Suzanne Wold-Burkness (woldx018@umn.edu), Department of Entomology, University of Minnesota

The Newsletter is published weekly from May through August, cooperatively, by the Minnesota Department of Agriculture (MDA) and the University of Minnesota (U of MN). Reports are posted on the U of MN and MDA web sites on Fridays. If you have suggestions and/or comments, please send your contributions by 4 p.m., Wednesday to Jeanne Ciborowski, 651-201-6217, jeanne.ciborowski@state.mn.us , MDA, 625 Robert St. North, St. Paul, MN 55155. You can access the Newsletter at the U of MN web site in htm format at: www.vegedge.umn.edu/MNFruit&VegNews/mnindex.htm and at the MDA web site in pdf format at: www.mda.state.mn.us/plants/pestmanagement/ipm/ipmnews.htm

Partial funding for this publication is provided through partnership agreements with the Minnesota Fruit and Vegetable Growers Association (MFVGA) and the United States Department of Agriculture – Risk Management Agency (RMA). These institutions are equal opportunity providers.

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Last Revised May, 2007 by woldx018@umn.edu
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