In this Issue:
New IPM Publications for 2006!
VEGETABLE NEWS
Vegetable Insect Pest Update - Southern Minnesota
STRAWBERRY NEWS
Strawberry Weekly Pest Sampling Data
Tarnished Plant Bug Damage, Frost Damage, or Boron Deficiency?
APPLE NEWS
Apple Maggot – Adult Emergence Data for Five Minnesota Orchards in 2004 & 2005*
Apple Trap Note – What's that Insect?
| Vol 3 No. 6 | June 23, 2006 |
Tarnished Plant Bug Damage, Frost Damage, or Boron Deficiency?
Thaddeus McCamant, Specialty Crops Management Specialist, Northland Community & Technical College
Strawberry growers in southern Minnesota began picking on June 10th, while growers in central Minnesota opened a week later. The crop this year is mixed. Some farms have an excellent crop, while others lost fruit to frost or insects. There are many reports of deformed berries, which could be caused by frost, tarnished plant bug, or boron deficiency.
 TPB damage on 'Kent' strawberries. The king berry is slightly damaged, the secondary berries are unmarketable. The last fruit is healthy (most likely because the field was sprayed). |
 Frost damage in 'Mesabi' strawberries. Note, the lower berry is flat, but without the seeds associated with TPB damage. |
If you see deformed fruit in the field, you should inspect the fruit to see if the losses were due to tarnished plant bug or frost, as the two types of damage are easily confused. If most of the fruit was damaged by tarnished plant bugs, you will need to make appropriate control measures next year.
Frost often kills or deforms the king berries, leaving the secondary berries with little or no damage. Tarnished plant bugs usually cause little damage to the king berry, while destroying secondary blooms. When trying to differentiate between frost and tarnished plant bug damage, look at the whole cluster. With frost damage, healthy and damaged fruit will be on the same cluster. With tarnished plant bug damage, the whole cluster is usually damaged.
Tarnished plant bugs damage the tip of the berry first, giving the berry the characteristic seedy end, or “cat face”. Customers will not notice minor tarnished plant bug damage. With frost damage, any side of the berry can be deformed. If the sides of the fruit are damaged, and the tip is not seedy, you have frost damage, not tarnished plant bug. Quite often, with frost damage, you will see a suture mark between the normal and deformed sides of the berry.
If a field was left unsprayed, tarnished plant nymphs will be crawling through the field at the start of picking. 4th and 5th instar nymphs are big enough to crawl between clusters. Currently, the nymphs are turning into first generation adults.
Every year, I see a field of 'Glooscap' or 'Mesabi' with severely deformed berries. Crop losses in 'Glooscap' fields with deformed fruit vary from 20 to 90%. The affected fields are scattered across the state, and a poor field one year often produces well the next, unless the owner plows under the field in disgust. I am still trying to determine the cause of the deformed fruit. One possibility is boron deficiency.
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.
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. ©1999-2006 Minnesota Extension Service, University of Minnesota. All rights reserved. Contact copyright@extension.umn.edu for information on reproduction or use of this material.