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Serving: IA

This Week's Crop Gospel According to George

Harvest is progressing with many farmers now done with soybeans and waiting for warm temperatures and drying winds to lower corn moisture of the crop in the field and reduce artificial drying costs. "Both corn and bean yields vary across our area depending on soil type and seasonal rainfall," says Iowa State University Extension crop specialist George Cummins at Charles City in far northern Iowa.

Soybean yields reported usually fall within the 40 to 65 bushel per acre range. Corn yields reported this year vary from 80 to 220 bushels per acre. As a general prediction, it appears that county average yields for both corn and soybeans will be about 10% less than 2005 figures but certainly better than the yield predictions in early August 2006, before the late season rains came.

At ISU winter meetings two years ago, Palle Pedersen, ISU soybean specialist, spoke on "producing 100-bushel per acre soybeans". He raised the bar and shared a list of management practices to improve yields. Cummins notes that you can do that through better variety selection, weed control, early planting, etc.

Farmers listened and have adopted many of Pedersen's recommendations. Soybean yields have been above trend line the last two growing seasons.

Farmers scout fields more often

The threat of bean leaf beetle or soybean aphid damage and the possibility of soybean rust have also had a "beneficial" effect. "We are scouting our fields more often, identifying potential problems and taking appropriate action in a timely manner," says Cummins. "The threat of these pests and awareness of reductions in grain yield and quality have provided incentives for appropriate research. Also the organization of coordinated scouting efforts across the state has helped to identify outbreaks and monitor the spread of harmful insects and diseases.

In a recent "Crop Notes" e-mail newsletter that Cummins sends to farmers and agribusiness professionals in his area of Iowa, he asked for information on acres treated for various pests. Respondents whose sales territory includes all or parts of 16 counties indicated the following:

Results of crop pest spraying survey

  • Of the 136,000 acres of soybeans represented by the survey, 13,000 acres were treated for soybean aphid this year. Of the treated acres, 9,000 acres or roughly 70% were considered " preventative treatments" – i.e. an insecticide added to a herbicide application with aphids absent or below threshold.
  • Approximately 4,040 acres of soybeans were treated for bean leaf beetle. That acreage figure breaks out as 100 acres of the overwintering generation; 2,600 as first generation and 1,240 as second generation bean leaf beetle. Of the treated acres, about 3,100 acres or over 75% were considered "preventative treatments."
  • A total of 35 acres were sprayed for spider mites this summer.
  • Approximately 450 acres of soybeans were treated for western bean cutworm – primarily in Buchanan County
  • About 3,300 acres were treated for potato leafhoppers with nearly everyone who responded to the survey saying they treat some acres. This total includes 274 acres that were sprayed two times and 137 acres that were sprayed three times.

Hailstorms in October are rare

Early morning on October 4, severe hail damage was reported in a narrow band from Northwood (Worth County) to St. Ansgar (Mitchell County). Lesser hail damage was reported along the Chickasaw/ Howard Co. border from Lourdes to Jerico to Protivin. The combine monitor in a neighboring soybean field was registering 46 bushel an acre on Friday after the storm.

From PM – 573 "Profitable Soybean Harvesting" 4 beans per sq. ft = 1 bu/ acre. This publication is useful in estimating preharvest and hail damage as above and also to determine total harvest loss and where it is occurring (gathering, cylinder and/or separation) during combining.

From PM- 574 " Profitable Corn Harvesting" 2 corn kernels/ sq. ft = 1 bu/ acre. In 1/ 100th of an acre (174.2' for 1- 30" row, 87.1' for 2-30" rows, etc.) each 3/4 lb. ear or it's equivalent in smaller ears = 1 bu/ acre ear loss. As above, this publication is useful in estimating preharvest losses and making combine adjustments to reduce harvest losses. Herbicide-tolerant volunteer corn may pose a problem in many of these fields going to herbicide-tolerant soybeans in 2007.

Look for new rootworm event for 2007

Fall Stalk Nitrate Test ( PM 1584) is an excellent tool to monitor N utilization and loss. Pulling the stalk samples gives valuable insights into corn variety selection, stalk rots, lodging problems, ear droppage and insect damage. Several farmers have adjusted their harvest schedules as a result of these observations.

Syngenta has received EPA registration approval for its corn rootworm event, "Agrisure RW". This event will be available to farmers for the 2007-growing season. ISU has not had this event in any of the public corn rootworm management trials to date. Trials are underway comparing the Monsanto and Herculux events with each other and their isolines in both first–year corn and continuous corn situations. Corn rootworm management is of great interest and will also be a keynote topic at the Crop Advantage Programs in Mason City and Waterloo in January," says Cummins.

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