CORN Newsletter: 2004-38, November 9, 2004

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C.O.R.N Newsletter 2004-38
November 9, 2004 - November 23, 2004

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Soybean Cyst Nematode – Sampling, HG Type Testing And Plans For Next Year
by Anne Dorrance


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Soybean cyst nematode continues to take yield from Ohio soybean crop and now is a good time to take assessment of your fields. Fields where the drainage was good, but the yield monitors had low readings or the “chatter” from the beans took a dip are the places to sample for soybean cyst nematode. This nematode has a tendency to sit in pockets. If you were walking your fields, these were the areas where the bean height drops from knee high to mid-calf high or waist high to knee high depending on your field. These areas are getting bigger. I walked some fields and what used to be a car size circle has now expanded to a football size area. Because cysts do sit in pockets, it is possible to miss them when collecting soil samples. For every 10 to 20 acre field, collect soil cores as you would for fertility samples. Many folks use the zig-zag pattern. When sampling, aim your soil probe for the root zone. If you probe between rows, you will have a lower likelihood of hitting a cyst pocket. If you have GIS information and can go back to the spot where the yields took a hit – this would also be good. Take all of the soil cores and mix them thoroughly – and then send a good healthy quart of soil to the SCN testing lab.

Do you need to determine which HG type (Heterodera glycines), formerly called race type, of SCN populations are in your field. My answer is the same as it is for Phytophthora sojae, NO. For SCN we have one primary source of resistance that is currently in commercial varieties, PI88788. There are a few varieties with Hartwig or Peking sources of resistance. The management of these sources of resistance and SCN in general is to rotate. Rotate your crops, so when planting SCN resistant beans, the SCN populations are low (<2,000 eggs or 4-5 cysts per cup of soil) and follow this by rotating sources or resistance. SCN is also notorious in that it can also adapt to these sources of resistance. So we need to rotate sources of resistance by rotating soybean varieties. What is bad, is that this is all the resistance we have available and many of you know of the yield drag associated with the early releases. With Phytophthora, there are a few more tools in the tool box such as partial resistance and fungicide seed treatments.

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C.O.R.N. is a summary of crop observations, related information, and appropriate recommendations for Ohio Crop Producers and Industry. C.O.R.N. is produced by the Ohio State University Extension Agronomy Team, State Specialists at The Ohio State University and Ohio Agricultural Research and Development Center. C.O.R.N. Questions are directed to State Specialists, Extension Associates, and Agents associated with Ohio State University Extension and the Ohio Agricultural Research and Development Center at The Ohio State University.

Information presented above and where trade names are used, they are supplied with the understanding that no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.

TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868


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