Henry G. Taber, Faculty, Horticulture Department
Sweet corn production by Iowa vegetable growers ranks number one in percentage of growers and vegetable acreage grown in the state. Weed control is very important for high yield and attractive ear quality as measured by ear length, tip fill, and flag leaf color. Also, weeds in the row centers interfere with pest control sprays and make hand harvesting difficult. All sweet corn acreage is treated with a herbicide. A new herbicide, Callisto, became available in April 2005 that offered season long effective weed control. However, the label restricts rotational crops of cucurbits and snap beans to 18 months after application. This restriction could be a problem for some growers with limited land available for rotation.
The growers asked ISU to evaluate the effectiveness of Callisto for season long weed management, and the potential residue problem with vine crops and snap beans the following year. Their statewide organization, Iowa Vegetable/Fruit Growers Association, provided financial support to carryout the field studies at two locations Muscatine Island Research Farm, eastern Iowa (sandy soils), and the Horticulture Station, central Iowa (loam soils).
In the summer of 2005 the field study at both locations showed that Callisto alone, or in combination with other sweet corn herbicides, provided excellent broadleaf and grass control without detriment to yield and quality. Even double the recommended label rate did not reduce sweet corn yields or quality at either location. In 2006, potential Callisto carryover problem was evaluated at the central Iowa location with cucumbers, muskmelons, watermelons, and snap beans. The result was severe injury to all crops in the seedling stage of growth, except watermelon. Resulting yield and quality was reduced. These results were presented to growers at two summer field days and one winter conference.
As a result of the cooperative effort between growers and ISU personnel, sweet corn growers wishing to use the new Callisto herbicide must evaluate their rotational crop plan for a two year period rather than on an annual basis.
106 Green Industry (Commercial Horticulture and Forestry)
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September 25, 2006
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