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ABSTRACT: The main objective of this study was to describe the importance of cob rots in farmers' maize fields and reduced food quality through spoilage. During the 1997/98 season disease incidence and severity levels were evaluated in the Local, MH18, NSCM41, and NSCM51 varieties on farmers' maize from two villages in central Malawi. Farmer- and researcher-selected samples from farmers' harvests during the 1996/97 and 1997/98 growing seasons respectively were analysed in the laboratory for fungal contaminants. Another experiment was carried out on-station for comparative purposes using the four varieties. Each variety was inoculated with Stenocarpella maydis and Fusarium moniliforme and control plots were treated with sterile distilled water using the silk-spray method. Stenocarpella macrospora was the most predominant pathogen in both farmer- and researcher-selected small-holder farmers' maize. Fusarium moniliforme was also commonly isolated, though at low incidence levels. The results indicate that both 'healthy' and 'rotten' maize are contaminated by almost the same fungal species, but the levels of contamination were generally lower in 'good' than in 'rotten' maize. Cob rot infections were significantly high for NSCM41 followed by NSCM51, MH18, and lowest in the Local variety, both in the field and on-station trials (P < 0.05). High infection levels were more associated with S. maydis than F. moniliforme inoculations. We conclude that NSCM41 is more susceptible to cob rots followed by NSCM51, MH18, with the Local variety being most tolerant.
African Crop Science Journal (ISSN: 1021-9730) Vol 7 Num 4. 04/1999;