In this Issue:
GUEST ARTICLE
Leaf Analysis as a Guide to Apple Orchard Fertilization
VEGETABLE NEWS
Time to Watch for Squash Vine Borer and Squash Bug
STRAWBERRY NEWS
Strawberry IPM Update Plus Weather and Fruit Diseases
APPLE NEWS
Join us for the Upper Midwest Organic Tree Fruit Growers Network June Field Day
Weekly Trap Counts: June 6- June 15, 2005
| Vol 2 No.7 | June 20, 2005 |
Strawberry IPM Update Plus Weather and Fruit Diseases
Thaddeus McCamant, Specialty Crops Management Specialist, Northland Community & Technical College
The Strawberry bloom is ending in all parts of Minnesota except the Arrowhead region and in all varieties except Winona and other late berries. Tarnished plant bug numbers continued to drop this week, even in fields that were not sprayed. Clipper weevils are still active in fields that were not sprayed.
The constant rain of early June has made many berry growers nervous about fruit diseases. In Minnesota, three fruit diseases damage strawberries: gray mold, anthracnose and leather rot. Each disease is caused by a different fungus, and each fungus has different temperature and moisture requirements in order to infect your fruit.
Gray mold fungi overwinter on strawberry leaves. Wind moves the gray mold spores from the leaves to strawberry blossoms. Once on the blossoms, the spores do not grow and infect the fruit unless the temperature is above 60 °F, and the blossoms remain wet for over twelve hours. Once the fruit is infected, the fungus grows slowly and undetected until the fruit becomes ripe.
Anthracnose fungi live on leaves and petioles. The spores can only move onto the fruit with water. The spores will only start growing if the temperature is at or above 70 °F, and the fruit is wet. Anthracnose outbreaks are most common five days after a thunderstorm on a hot day.
Leather rot fungi live in the soil. The spores can only infect fruit if they are carried by water from the soil to the fruit. Leather rot is active at cool temperatures, and some spores can even swim short distances. Infections begin almost as soon the water touches the fruit. Leather rot infections are most common when water pools around fruit after a rainstorm, when water is splashed onto the fruit during a rainstorm or when water is splashed onto the fruit from tractor tires.
So far this June, we have had long wet periods for gray mold infections and excessive rain for leather rot, but we have not little warm rain for anthracnose.
For more information go to the MDA website:
Field Guide for Identification of Pest Insects, Diseases, and Beneficial Organisms in Minnesota Strawberry Fields at: http://www.mda.state.mn.us/ipm/strawberryfg/default.htm and Integrated Pest Management Manual for Minnesota Strawberry Fields at: http://www.mda.state.mn.us/ipm/berrymanual/default.htm
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, 651-297-3217, 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/
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.
The University, including the Minnesota Extension Service, is an equal opportunity educator and employer. ©1999-2005 Minnesota Extension Service, University of Minnesota. All rights reserved. Contact copyright@extension.umn.edu for information on reproduction or use of this material.