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Poster Presentations


Poster Presentations


Strategic placement of sentinel plots by combining ecozone and acreage maps -- South Dakota observations 2006

Presenter: B. E. Ruden

All authors and affiliations: B. E. RUDEN, M. A. Draper, and K. L. Maxson-Stein. South Dakota State University, Brookings, SD

The soybean rust sentinel plot network in South Dakota for 2006 consisted of 26 sites with 33 plots, including two sites with dryland/irrigated side by side, two sites with two maturity groups, one site with three maturity groups, and one site with dry field peas. Mobile monitoring of dry beans and field peas occurred at five locations throughout the year. Plots were strategically located in the soybean production areas of the state based on aggregated acreage (aggregations of 300,000400,000 acres were mapped out) and USGS ecozone maps. Ecozone maps combine topography and climatic factors to create various zones throughout the state. This layout maximized environmental exposure, while limiting plot number. Extension Service agronomy educators, trained as first detectors, monitored the sentinel plots on a weekly basis from the first week in June through hard frost, which occurred around September 20. Disease and crop development data, aphid populations, hourly temperature and humidity readings, and rainfall were recorded at each site. Foliar diseases were of minor importance in 2006. Septoria brown spot, a common disease in South Dakota, was fairly minor and generally not observed until August, when the crop was in the R4 to R6 growth stages. Bacterial blight, bacterial pustule, and downy mildew were also identified but at low severities. Soybean rustlike spores were detected in a dry deposition spore traps twice during the season. Dry conditions (early) and frost (late) arrested any development of disease following these spore showers.

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