MN Fruit & Vegetable IPM News - Vol. 3, No. 1

Various pest organisms, primarily arthropods (insects and mites), diseases, weeds, and mammals are associated with apple production in Minnesota and cause significant economic losses to commercial fruit growers. The focus of this guide is on arthropod pests and diseases of apple. Insect pests found in apple orchards can be classified into two groups depending upon which plant part is attacked. Direct pests are those insects that feed on apple fruits, while indirect pests are those that attack leaves, trunk, and other parts of the tree. Examples of direct pests of apple in Minnesota are apple maggot, plum curculio, codling moth, and other internal fruit feeders. Pests like spotted tentiform leafminer, aphids, and mites may affect yield if present in large numbers, but they are indirect pests since they do not directly injure fruits.

Insect pests can also be classified in terms of the seriousness of their infestation and effect on orchard economics. Major pests are those that have the potential to cause major economic losses to the grower. Usually, most direct pests that feed on fruit are also considered major pests. Apple maggot, plum curculio, and codling moth constitute the "big three" pests of apple in Minnesota and the upper Midwest . Indirect pests usually do not feed on the fruit, and although their activities may limit fruit yield they are considered minor pests. A third category of pest insects is the quarantine pests. Quarantine pests are insects not known to be established in a given area. The flat scarlet mite and apple ermine moth are current examples of quarantine pests in Minnesota .

Not all insects and mites in apple orchards are harmful. Many arthropods, such as lady beetles, predaceous bugs, spiders, and predator mites benefit the grower by feeding on pest insects and mites. Bees also fall into this category of beneficial arthropods by aiding apple pollination.

Many diseases of apple are not restricted to one part of the tree. For example, apple scab attacks the fruit, leaves, and flowers. Powdery mildew can also infect many parts of the tree. Fire blight is a tree disease infecting leaves, shoots, limbs, and trunk, but it can infect fruit and root stock. The fungal disease complex known as sooty blotch and flyspeck is, however, restricted to the fruit.

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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 Jean Ciborowski, 651-201-6217, jeanne.ciborowski@state.mn.us, MDA, 625 Robert St. North, St. Paul, MN 55155-2538. 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: http://www.mda.state.mn.us/ipm/ipmnews/

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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