In this Issue:

VEGETABLE NEWS

Summary of Corn Earworm and European Corn Borer Dynamics in 2007

Insecticide Efficacy for Corn Earworm: Small-Plot Trial 2007

BERRY NEWS

The Benefits of Frost

Coming Attractions

APPLE NEWS

2007 Trap Catches for Codling Moth and Dogwood Borer at 5 Apple Orchards Monitored by the MDA

Minnesota Department of Agriculture’s 2007 Exotic Apple Insect Pest Survey

To Our Readers

Order: 2007 Minnesota Vegetable Guide

Insect, Pest Fact Sheets

The Benefits of Frost

Thaddeus McCamant, Specialty Crops Management Specialist, Northland Community & Technical College

On September 15, most of the state was hit by a frost that killed pumpkin vines, marigolds and tomato plants.  Many parts of Central Minnesota recorded overnight lows in the mid twenties.  Most people dread the first frost as a sign that the growing season and the summer have reached their inevitable end.  This year, people were more upset, because the first frost was up to a month early in southern Minnesota.

Strawberry growers can take advantage of the fall frosts.  Strawberry leaves are highly frost tolerant, and plants continue to make flower buds and small leaves as long as the daytime temperature exceeds 45ºF.  Meanwhile, some of the worst weeds of this summer suddenly turned brown when the sun rose on September 15.  Pigweed, crabgrass and purslane all grew rapidly in the hot dry weather in July and August, choking out berry plants where they were not controlled. All three weeds are sensitive to frost, and they rarely cause economic losses in strawberry fields after the first year.  The first frost marks the last day you had to worry about pigweed in new fields.  Dead pigweed may look ugly in a strawberry field, but they cause no harm to berry plants.

With the annual weeds killed, strawberry growers have a better view of weeds that will threaten their fields during the next two or three years.  Most of the weeds you will be fighting in established fields are perennials, most are frost tolerant, and many are still small.  The window for pulling weeds in the spring is only three or four weeks, which is also a time when people are busy.  In the meantime, a dandelion the size of a small saucer in April can become a large serving plate in May.  In the fall, dandelions and other weeds grow quite slow and can be killed anytime in the six weeks between the first frost and covering the plants with straw.  Here are weeds to look for:

Dandelions can be pulled just as easily in the fall as the spring. Common mallow has become common in many fields lately.  Mallow is resistant to 2,4-D and Stinger.  Its seeds are large, and resistant to many preemergent herbicides.  Large mallow plants with flowers should be pulled and removed from the fields.  Mallow seedlings can be killed with a hoe. White cockle seedlings can be killed with a hoe this time of year.  Quackgrass grows very well in cool weather, and at this time of year, it is sensitive to Roundup.  Strawberries are also extremely susceptible to Roundup in the fall, so be careful when spraying quackgrass near berries.      Musk thistle and bull thistle are biennials that form rosettes in the first year and flower the second year.  Both can be pulled, but musk thistle often sprouts from root pieces left in the soil.  Musk thistle rosettes pulled now will be weak and easy to control next spring.

Many growers will see the first frost as a sign to take a break from working in their fields, but the fields shouldn’t be ignored completely. Spending an hour removing mallow or other weeds can save ten hours of weeding during the time crunch next April.

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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.

DISCLAIMER

Reference 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 September, 2007 by woldx018@umn.edu
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