MN Fruit & Vegetable IPM News - Vol. 1, No. 11

Codling moth: Summer (second generation) adults of codling moth (CM) must be properly monitored using pheromone-baited traps. Egg-laying by summer adult females begins around 1060 DD base 50ºF, counting from biofix. Therefore, conventional insecticides targeted against second generation larvae should be applied around 1250 DD base 50ºF, counting from biofix. CM pressure can also be evaluated by sampling fruits for injury. Remember that if not effectively controlled second generation larval populations will overwinter and may result in an increased CM pressure the following spring.

Apple maggot: Apple maggot (AM) has a single generation per year in Minnesota, and peak emergence usually occurs in late July/early August. Growers should continue to monitor AM using baited red spheres. The threshold for treatment is 5 flies per trap. Most of the conventional insecticides have residual activity for about 2 weeks after application. After the insecticide has lost its residual activity you should resume monitoring and treat again when you catch 5 flies per trap. Remember that AM overwinters as pupae in the soil. Therefore, orchard sanitation and removal of fallen fruits is a key factor to consider in its management.

Plum curculio : Plum curculio (PC) overwinters as adults in the soil. These adults emerge in the spring, feed, mate, and reproduce. Eggs laid by the females develop within the fruit and emerge as adults in July and August. Upon emergence, the summer adults feed on the developing fruit throughout the season but do not reproduce. In the fall they find hibernation sites in ground litter or the soil where they pass the winter. This summer population of PC must therefore be effectively controlled not only to prevent significant fruit damage, but also to reduce the number of adults making it to the next season. Growers should continue to monitor for PC adults and feeding injury throughout the season.

Obliquebanded leafroller : There are two generations of obliquebanded leafroller (OBLR) in Minnesota. First generation adults are active from mid June to late July. Larvae from these summer adults (first generation adults) feed on leaves and developing fruit between July and August. Fruit injury usually occurs around fruit clusters. These larvae should be monitored and controlled in order to prevent economic loss. Second generation adults start to emerge around late July to early August. The progeny of these late summer adults will overwinter as third instar larvae.

European red mite: European red mite (ERM) usually occurs in the orchard throughout the season, with multiple generations per year. Therefore, scouting for ERM should continue through the season. Growers should remember that the threshold for ERM increases as the season progresses: 5 mites per leaf in July and 7.5 mites per leaf in August.

Other insects: Other insects that may pose significant problem to growers include aphids, leafhoppers, and tarnished plant bug. Growers should continue to watch for these sporadic pests. Redbanded leafroller (RBLR) is another pest to monitor. With three generations per year in Minnesota, severe RBLR infestation can create some problems. The main problem is caused by summer larvae when they feed on apple.

*(By Henry Fadamiro - Reprinted from Apple & Strawberry Report, July 18, 2002)

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ACKNOWLEDGEMENTS

Co-Editors: Bill Hutchison, Department of Entomology, University of Minnesota, hutch002@umn.edu
Jeanne Ciborowski, Minnesota Department of Agriculture, Ag. Resources Division,jeanne.ciborowski@state.mn.us
Suzanne Wold-Burkness, Department of Entomology, University of Minnesota, woldx018@umn.edu

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., Tuesday to Jeanne Ciborowski, 651-297-3217, jeanne.ciborowski@state.mn.us , MDA, 90 W. Plato Blvd., St. Paul, MN 55107-2094. 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/biocon/fruitreports/default.htm

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

DISCLAIMER

References to products in this publication is not intended to be an endorsement to the exclusion of others which may have similar uses. Any person using products listed in this publication assumes full responsibility for their use in accordance with current manufacturer directions.

Last Revised July 22, 2004.
The University, including the Minnesota Extension Service, is an equal opportunity educator and employer. ©1999-2004 Minnesota Extension Service, University of Minnesota. All rights reserved. Contact copyright@extension.umn.edu for information on reproduction or use of this material.