Epidemiology of Maize Root Rot in South Africa

Maize roots were rapidly infected by soil inhabiting fungi as soon as they differentiated. The first tissues to develop were the seminal roots and mesocotyls. As their function became superseded by that of the adventitious roots, they rapidly became, completely rotted. Adventitious root rot developed slower and the roots did not become as severely rotted. Numerous fungi were isolated from the roots. The most frequently isolated were Helminthosporium pedicellatum and Fusarium moniliforme. Trichoderma sp. was the next most frequently isolated fungus; it was, however, significantly less frequently isolated than the above. Young and Kucharek (1977) found that the fungi isolated from maize roots occur in communities associated with certain plant growth stages. This was not clearly evident in this study. Numbers of root lesion nematodes (Pratylenchus species) correlated non-significantly with fungus frequencies and root rot.