Another annual sweet corn pest, Corn Earworm (CEW), reached high numbers on late-planted corn this year, e.g., with 100% of the ears infested in untreated check plots at Rosemount (Dakota Co.). As we noted in September, we initiated a monitoring program to assess the degree to which 2003 populations, which migrate each year from the southern states, may have developed resistance/tolerance to selected pyrethroid insecticides. Results from this work should be available by March/April, 2004. See Sept. 12 issue for more information.

The bean leaf beetle (BLB) was again present at fairly high numbers in May-June this year, despite having severe winter weather last year. New research by Kathleen Bennet on the impact of BLB on defoliation and yield loss in snap beans was successful. Results of the first-year studies may be presented at winter grower meetings; these studies will be repeated in 2004.

Also of interest this spring, was our first observation of BLB feeding on early squash plantings. Feeding damage, particularly on cotyledons, was heavy in the field (see photo, left). Bob Koch and Eric Burkness collected field data documenting the damage to squash, and Bob subsequently conducted a lab-based choice test and no-choice feeding experiments with squash, pumpkin and cucumber. In the no-choice experiments, BLB fed on all 3 cucurbits, but damaged cucumber more than pumpkin and squash.

In snap beans and other crops, potato leafhopper (PLH) infestations were very high, possibly hitting a record high for the past 15 years in Minnesota! A considerable amount of alfalfa was sprayed this year, due to PLH. In addition to foliar insecticides, seed treatments in snap beans (Cruiser, Gaucho) provided significant control. These results will be presented in future research reports.

Fruit Crop Insects: Yet another interesting occurrence this year was the recent movement of the Multicolored Asian Lady Beetle (MALB) from field crops to ripening fruit, and subsequently to homes and buildings in preparation for overwintering. MALB feeding activity on fruit (particularly apples and grapes) in early fall, as temperatures begin to cool, is becoming a growing problem for Minnesota fruit growers. This past fall, we again documented fall infestations in grapes, apples and raspberries (see photos, below). In follow-up lab studies, Bob Koch confirmed that the lady beetle does not cause direct damage to apples or grapes, but is highly attracted to the fruit once the fruit skin has been broken by other insects (wasps), birds, or physiological splitting (e.g., in response to excessive rainfall). During this time, the beetles seem to be attracted to the high sugar content of fruit juice, in preparation for overwintering. For all crops, the infestations usually build just before harvest, making removal of the beetles difficult. New research is needed to evaluate cost-effective control strategies for MALB in fruit crops.

New Insect Pest Award for 2003. Although primarily an alfalfa pest (at this time), our new insect pest award this year goes to the Cowpea Aphid (CA), a recent immigrant from California, Arizona, via Missouri and Iowa. Fritz Breitenbach, Minnesota Extension Service, Rochester, first noticed small, black aphids in alfalfa, that were likely the cowpea aphid (see photo, left). Soon after we noticed infestations at Rosemount, reports were also noted in Wisconsin. The map below shows the infestation in 2003. More information about this aphid, and what it could mean to alfalfa growers is available in the August 8th issue.

New Insect Pest and Beneficial Fact Sheets for 2003 -- In response to questions about key insect pests, we developed three new fact sheets this year. New fact sheets are available for:

• Multicolored Asian Lady Beetle
• Bean Leaf Beetle
• Tomato Hornworm

Thanks again for your interest in the MN Vegetable IPM Newsletter! Feel free to let us know of any new topics you would like to see covered. Send your suggestions to Suzanne Wold Burkness: woldx018@umn.edu

Last Issue for 2003: Although this is the last issue for 2003, we will continue to provide IPM Updates to the VegEdge website throughout the “off-season”. You might want to bookmark the Fact Sheet site for VegEdge, for seasonal updates: http://www.vegedge.umn.edu/intro/pestfact.htm

New VegEdge Coming: This winter, look for a new section on “Research Updates” and a completely new re-design of the VegEdge site! To stay current with Pesticide label changes, new Crop Profiles for MN, and other IPM News, check out our North Central Region, IPM Center site for MN at: http://pestmanagementcenter-mn.coafes.umn.edu/