Observations of the breakdown of thiram at different moisture levels in stored grain sorghum.

IT HAS been the common practice in some rural parts of India to store sorghum in
underground pits during the glut season and release it to the market during the lean
period after storage for 3-4 months. In some cases, due to inclement weather conditions
during harvest, grain with relatively high moisture content is stored in underground
pits. The relative humidity of the atmosphere in such storages will be 75-90%,
(due to high moisture in the grain), and under such storage conditions fungal
infection poses a serious problem. Although many potent antifungal agents are known,
their use to prevent the fungal attack in storages has received little attention. It was
found that under such storage conditions, sorghum with a moisture content of over
15% became infected with fungus within one week even in the presence of large doses
(290-310 ppm) of thiram (tetramethylthiuram disulphide), while that with moisture
content less than 15% was still free of infection for more than 90 days. In addition
thiram even at 35 ppm on treated grain, has been reported to damage the egg production
of hens, when the grain was fed to birds, both decreasing the total number
produced, and causing soft shells (WAIBEL et al., 1955). The present study was
undertaken to investigate the relationship between moisture content and the degradation
of thiram so as to arrive at a critical moisture content for sorghum, above which
thiram would be ineffective.