During the course of the present study various organisms were found to be associated with decayed seeds and infected roots, mesocotyls, plumules and crowns of maize, both in the greenhouse and in the field. The organisms found most often on the decayed seeds were Pythium debaryanum, Gibberella 'saubinetii, Penicillium oxalicum, Trichoderma lignorum and Fusarium spp. Those occurring on diseased roots were Pythium debaTyanum, P. gmminicola, Gibberella saubinetii, Helminthosporium sativum,

more »

... onia solani, Trichoderma ligno1'"'um, Fusarium monili/orme and Fusar-.ium spp. Isolations made from infected mesocotyls yielded chiefly Gibbe1"ella saubinetii, Rhizoctonia solani, H elminthosporium sativum, Penicillium oxalicum, Trichoderma lignorum and Fusarium spp., and those from diseased plumules yielded Gibberella saubinetii, Fusarium spp. and Rhizopus sp. The organisms that appeared on the crowns were Diplodia zeae and Fusa1"ium monili/orme. These organisms may be divided into three groups based on their pathogenicity on maize in the greenhouse and under field conditions: (a) highly destructive, Pythium debaryanum, Pythium graminicola and Gibberella saubinetii; (b) moderately destructive, Rhizoctonia solani, Helminthosporium sativum, Diplodia zeae and Penicillium oxalicum; (c) slightly destructive, Aspergillus niger, Fusarium moniliforme, Trichoderma lignorum, Rhizopus sp. and Fusarium spp.