In this Issue:
GUEST ARTICLE
Strategic Innovation by Karl Foord
VEGETABLE NEWS
SPECIAL FEATURE
STRAWBERRY NEWS
Strawberry Renovation
APPLE NEWS
Apple Scab Infections
| Vol 1 No. 10 | July 19, 2004 |
Strawberry Renovation
Matted row strawberry plantings must be renovated after harvest to establish new crowns for next year’s crop. For best results, renovation should be started immediately after the harvest, to promote early runner formation. The earlier a runner gets set, the higher its yield potential for the following year. Renovation should be completed by the end of July in normal years. Now that harvest is about over, growers should begin renovation. The following steps describe renovation of commercial strawberry fields.
Weed control: Annual broadleaf weeds can be controlled with 2,4-D amine formulations. Check the label, as only a few products are labeled for use on strawberries. Be extremely careful to avoid drift when applying 2,4-D. Even though the amine formulation is not highly volatile, it can volatilize under hot, humid conditions and can cause damage to desirable plants a considerable distance from the site of application. Some damage to strawberries is also possible. Read and understand the label completely before applying 2,4-D amine (or any pesticide). If grasses are a problem, sethoxydim (Poast) will control most annual and some perennial grasses. Do not tank mix Poast and 2,4-D.
Mow: Mow the old leaves off just above the crowns, three to five days after herbicide application. Do not mow so low as to damage the crowns.
Fertilize: A soil test will help determine phosphorus and potassium needs, but foliar analysis is a more reliable measure of plant nutrition. For foliar analysis, sample the first fully expanded leaves following renovation. Your local fertilizer dealer may be able to recommend a testing lab, or contact the research analytical lab at the Univ. of Minnesota to find out about submitting leaf samples for analysis: 612-625-3101 or http://ral.coafes.umn.edu/
Nitrogen needs can be assessed through foliar analysis, but strawberries in Minnesota typically need from 40 to 80 pounds of nitrogen per acre, depending on the vigor of the planting. It’s better to split the total nitrogen into two (or even three) applications at regular intervals, rather than to apply it all at once. A good plan is to apply about half at renovation and half again in late August.
Subsoil: If picker traffic has been heavy on wet soils, compaction may be severe. Subsoiling between rows will help break up compacted layers and provide better infiltration of water. Subsoiling may also be done later in the sequence.
Narrow the rows: Reduce the width of rows based on your row spacing, the aisle width desired, and the time of renovation. Wider rows lead to low productivity and increased disease pressure. Since more berries are produced at row edges than in the middle, narrow rows are superior to wide rows. Narrow rows will give better sunlight penetration, better disease control, and better fruit quality. A desirable final row width to attain at the end of the season is 12 to 18 inches. This means that rows can be narrowed to as little as eight inches during renovation; a vigorous planting will fill out and widen the rows. Use a roto-tiller or cultivator to achieve the reduction. Some growers use Paraquat to narrow rows of varieties (such as Jewel) that don’t respond as well to mechanical row narrowing.
Cultivate: Work in the straw between rows and throw a small amount of soil over the row. Strawberry crowns continue development at the top, and new roots are initiated above old roots on the crown, so one-half to one inch of soil on the crowns will facilitate rooting. This also helps cover any straw in the row and provide a good rooting medium for the new runner plants.
More weed control: Pre-emergence weed control should begin immediately. Dacthal, Sinbar, and Devrinol are commonly used. Check the product labels carefully and remember that it’s a federal law that you may only use pesticides in accordance with their labels. Devrinol must be incorporated by irrigation, rainfall, or cultivation to be effective. Rate and timing of Sinbar application is critical. If regrowth has started at all, significant damage may result. Some varieties are more sensitive to Sinbar than others. If unsure, make a test application to a small area before treating the entire planting. Sinbar should not be used on soils with low organic matter. If Sinbar gets onto strawberry leaves, irrigate to wash it off.
Irrigate: Water is needed for both activation of herbicides and for plant growth. Don’t let the plants go into stress. Ideally the planting should receive one to one and a half inches of water per week, from either rain or irrigation.
Cultivate: Sweep runners into the row until plant stand is sufficient. Thereafter, or in any case after September, any runner plant not yet rooted is not likely to produce fruit next year and is essentially a weed and should be removed. Coulter wheels and/or cultivators will help remove these excess plants in the aisles.
Continue to irrigate and fertilize: Adequate moisture and fertility during August and September will increase fruit bud formation and improve fruit yield for the coming year. Continue irrigation through this time period and fertilize if necessary. The second application of 20 to 40 pounds of N per acre, depending on the vigor of the planting, should happen in August.
*Adapted from an article published in Facts for Fancy Fruit (June 20, 2001) by Bruce Bordelon, Department of Horticulture and Landscape Architecture, Purdue University.
(MDA does not endorse any product or company where trade names are used. Always check to make sure the pesticide is labeled for intended use and read the label before using any pesticide.)
ACKNOWLEDGEMENTS
Co-Editors: Bill Hutchison, Department of Entomology,
University of Minnesota, hutch002@umn.edu
Jeanne Ciborowski, Minnesota Department of Agriculture, Ag. Resources Division,jeanne.ciborowski@state.mn.us
Suzanne Wold-Burkness, Department of Entomology, University of
Minnesota, woldx018@umn.edu
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., Tuesday 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/default.htm
Partial funding for this publication is provided through partnership agreements with the Minnesota Fruit and Vegetable Growers Association and the United States Department of Agriculture – Risk Management Agency (RMA) and the RMA Community Outreach and Assistance Partnership Program. These institutions are equal opportunity providers.
DISCLAIMER
References 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 July 15, 2004.
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