Soilborne diseases in maize-based cropping systems in southern Malawi: incidence and farmers' perceptions
various legumes. root crops and other cereals, A survey conducted during 1990 showed that farmers are less knowledgeable of soilborne plant diseases than of foliar diseases. They ascribed symptoms such as seed rot, damping-off, wilting and yellowing to factors unrelated to microbial attack. but nevertheless rated maize streak and Fusarium wilt of pigeonpea as major constraints to optimal crop production in areas with a high incidence of these diseases. Subsequent investigations during the 1990/91 and 1991/92 cropping seasons indicated that soilborne diseases were mostly of minor importance. the exception being Fusarium wilt of pigeonpea which caused stand losses of up to 50 %. However, diseases like damping-off of bean and maize tended to be severe in certain areas. Root and soil samples collected from major crops produced a variety of pathogenic or potentially pathogenic organisms. Maize roots yielded mainly Fusarium moniliforme. F. oxysporum and Sclerotium rolfsii, whereas bean roots were colonised by F. oxysporum. F. solani, F. equiseti, F. graminearum, S, rolfsi/, Macrophomina phaseolina, Rhizoctonia sp, and Penicillium sp. Fusarium udum was readily isolated from stem sections of pigeonpea plants exhibiting wilt symptoms. Pratylenchus spp., particularly P. zeae and P. brachyurus, were the most commonly encountered nematodes extracted from maize root and soil samples, whereas Meloidogyne javanica caused root-knot in bean and pigeonpea.
Hillocks, R.J.; Khonga, E.B. Soilborne diseases in maize-based cropping systems in southern Malawi: incidence and farmers’ perceptions. African plant protection (1996) 2 (2) 131-138.