STORAGE STABILITY OF FARM-STORED RAPESEED AND BARLEY

Abstract

Rapeseed was more vulnerable than barley to pest infestation when 46 and 52 t, respectively, were stored in farm bins in Manitoba during 1973–76. The fat acidity of unheated barley did not increase in 3 yr, but that of rapeseed increased by 65% in the 1st yr and 120% by the 3rd yr; in a small heated pocket of rapeseed, fat acidity rose in the 3rd yr by 1,000%. Cladosporium was the major field fungus of rapeseed and Alternaria of barley. Penicillium and members of Aspergillus glaucus group were the major storage fungi associated with rapeseed. Unlike barley, rapeseed was heavily infested by grain mites, Acarus immobilis, Glycyphagus destructor, and their predators, Blattisocius keegani and Cheyletus eruditus. Test insects, Cryptolestes ferrugineus and Tribolium castaneum, introduced in both bins, could not overwinter. Turning of both crops in the spring reduced temperature and moisture differences between the warm center and cooler edges, but it also dispersed fungal spores and mites throughout the bulks. A succession of storage fungi developed in a rapeseed hot spot, caused by moisture leaking through the wall. Occurrence of A. candidus coincided with germination loss of rapeseed. High CO2 concentration (4%) for over a 9-mo period was found in the hot spot in the rapeseed bulk.