Submitted to: Association of Operative Millers
Publication Type: Trade Journal
Publication Acceptance Date: 8/15/2006
Publication Date: 10/1/2007
Citation: Flinn, P.W., Reed, C., Hagstrum, D.W., Phillips, T. 2007. Seasonal and spatial changes in insect density in commercial elevator bins: Implications for phosphine fumigation. International Miller (Association of Operative Millers), October 2007, p. 36-40. Interpretive Summary:
Technical Abstract: Results of a 5-year, area-wide IPM program for managing insect pests in commercial grain elevators in Kansas and Oklahoma showed that insects generally invaded stored grain from the top of the grain mass. In stored wheat, the rusty grain beetle was the most common insect species from June-September, but was often surpassed by the lesser grain borer after 3-4 months of storage. The red flour beetle was the third most common insect species found in stored wheat. Studies that measured the movement and concentration of phosphine gas in concrete bins over time indicated that fumigant movement was dictated by air currents, which in turn, were a function of the difference between the average grain temperature and the average outside air temperature during the two weeks following application of the fumigant pellets. When the grain was warmer than the average outside air temperature during these two weeks, the phosphine gas would move upward through the grain mass. When the grain was cooler than the average outside air during these two weeks, the fumigant moved downward. Because insect problems normally occurred in the top of the grain mass early in the storage season (June-August), a uniform application of fumigant pellets was more effective when the grain and outside air temperatures were similar during the two weeks following application of the fumigant. When grain was much warmer than the average outside air temperature during these two weeks, applying more fumigant pellets into the bottom half of the grain mass was the most effective strategy. If the grain temperature is expected to be cooler than the average outside air temperature during the two weeks following application of the fumigant, applying more pellets to the upper half of the grain mass would be the best strategy.