In this Issue:
STRAWBERRY NEWS
Strawberry Update
VEGETABLE NEWS
Section 18 Approved for Coragen
APPLE NEWS
The Minnesota Farmers’ Market Association
There will be NO Newsletter next week – We’ll be back on July 25th.
| Vol 5 No. 8 | July 11, 2008 |
Strawberry Update
Thaddeus McCamant, Specialty Crops Management Specialist, Northland Community & Technical College
The strawberry season in southern Minnesota is slowly winding down. Most berry growers in the metro area will pick their Jewel fields for the last time on the weekend of July 12-13. Growers in central Minnesota will be able to pick a week longer, while growers in northern Minnesota opened on July 7. Overall, yields and consumer demand have been extremely high so far, and there are few insect or disease problems.
Raspberries and blueberries are starting to ripen right now, and most raspberry and blueberry growers in southern Minnesota anticipate opening either this weekend or at the beginning of next week. So far, there are no major quality problems with either raspberries or blueberries.
The late year could cause problems with strawberry renovation. Fields with healthy plants and a high plant population should be mown at the end of harvest, because mowing typically increases yields and decreases leaf diseases. Strawberry plants should be mown early enough in the summer so that they can develop a full canopy of leaves before the plant starts forming flower buds in the middle of August. Strawberry plants mowed before July 25 will have time to grow new leaves. With the late and extended season, many farms will be picking at the end of July. If your harvest continues to the end of July, you should either close the fields so that you can mow, or you may have to skip mowing altogether. If you are applying 2-4, D at renovation, you can spray after mowing.
Black Root Rot
At the end of harvest, problems caused by black root rot are most likely to show up. Most of the year, plants with black root rot look normal, but lack the vigor and plant height of normal plants. Harvest and hot spells take a toll on the plants, and many plants with black root rot suddenly die shortly before renovation. Typically, about 75% of the plants in an infected section of row die.
Black root rot is a soil disease, often found in distinct sections of a field. Several different fungi and bacteria contribute to black root rot. In Minnesota, nearly all plants with black root rot have the fungus Rhizoctonia, a disease that also infects potatoes. Black root rot occurs in both sandy soils and clay soils. The disease is most likely to occur in fields that have been in strawberries for several planting rotations without a two to three year fallow period.
If a field does have black root rot, it should be plowed under. The only time to cure black root rot is during fallow periods. Sorghum-sudan cover crops do appear to reduce the disease. Sorghum should be plowed into the field while the leaves are still green. Other cover crops that may reduce black root rot include radishes and mustards that help sterilize the soil. Several growers with black root rot have had good results with leaving the fields in alfalfa for several years.
In studies conducted in Michigan and Ohio, Cavendish was the most resistant variety. From my experience here in Minnesota, K93-10 is even more resistant, but even though K93-10 will have a thick canopy in infected soils, it produces less fruit than susceptible varieties.
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, 651-201-6217, 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 May, 2008 by woldx018@umn.edu
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