Potential for mycotoxin-producing fungal growth in various agro-ecological settings and maize storage systems in southwestern Ethiopia

The objective of this study was to evaluate the potential growth of mycotoxin-producing fungi under different agro-ecological settings and storage methods in southwestern Ethiopia. The districts of Sokoru, Omonada, and Dedo, representing three agro-ecological settings, were considered for the study. Six farmers' fields were selected from each agro-ecology for monitoring pre-harvest weather conditions, while three farmers' and three collectors' storage systems were considered for post-harvest study. Additional warehouses were also included for current study. Fungal pathogens were isolated and identified once per month over a six-month storage period. Both long-term climate and pre-harvest weather data indicated that all agro-ecological conditions were conducive to the growth of the target fungal species. Temperatures inside the farmers' storage systems showed significant (P = 0.04) positive correlations with ambient conditions. Significant (P < 0.05) positive correlations were also observed between the relative humidity under the farmers' storage and the ambient conditions. In contrast, there were no significant correlations between the collector's storage and ambient conditions for either temperature or relative humidity. A simple linear regression model revealed that there was a negative relationship between frequency of mycotoxin-producing fungi and the temperature inside the farmers' storage systems; whereas, fungal occurrence was positively and significantly (P < 0.05) correlated with the relative humidity. Both temperature and humidity were associated with fungal frequency of occurrence in the collectors' store-houses and the wholesalers' warehouses. The farmers' traditional storage methods are not climatically controlled to maintain post-harvest product quality. Therefore, a simple and accessible climate-controlled storage structure is necessary for the resource-poor growers of the study area.