[EBOOK] A Pictorial Guide for the Identification of Mold Fungi on Sorghum Grain, S S Navi, R Bandyopadhyay, A J Hall, and Paula J Bramel-Cox, International Crops Research Institute for the Semi-Arid Tropics

People need food, and a crop is not food until it is eaten. A program to reduce storage losses probably could result in an increase of available food in some developing countries, and might also assure that whatever increases in production occur in future would be used for the nourishment of people, not for feeding pests. Overall postharvest losses of cereals, oilseeds, and pulses have been estimated at 20% of the harvested crop in Africa, Asia, and Latin America. The Food and Agriculture Organization of the United Nations (FAO) has estimated losses of these commodities at 10% on a worldwide basis (FAO/ICRISAT 1996). In individual cases losses may be much greater and it is suggested that losses at the farm-level of 35-50% followed by 10-12% in traders' stores and further 5% in centralized stores may not be uncommon (Booth and Burden 1983).

There is little doubt that grain mold in its broadest sense constitutes one of the most important biotic constraints to sorghum (Sorghum bicolor (L.) Moench) improvement and production. The real and potential importance of grain mold has been emphasized for Africa, the Americas, and India (Forbes et al. 1992). Grain mold fungi have repeatedly been associated with losses in seed mass, grain density, and germination and other damage relating to storage quality, food and feed processing quality, and market value of the grain. More specifically, the effects of fungi in quality loss in stored grains are: (1) decrease in germinability; (2) discoloration of part or all of the seed or kernel; (3) heating and mustiness; (4) various biochemical changes; and (5) production of toxins that if consumed may be injurious to humans and to domestic animals.

Grain mold continues to receive much attention because of the growing concern for deleterious nature of subacute dosages of mycotoxins on animals. Mycotoxin content of grains contaminated during pre-harvest increases when the grains are stored. There are species of 32 dematiaceous hyphomycetes which produce mycotoxins and other metabolites. More species in the genera Alternaria. Bipolaris, Curvularia, Drechslera, Exserohilum, and Fusarium have been investigated for mycotoxins than those in the other fungal genera (Sivanesan 1991). In addition, species of Aspergillus can produce aflatoxins (Pitt 1991).

Seeds carry mycoflora which vary with the host species. This is especially true for the more deeply seated mycoflora, whilst on the surface many "accidental guests" may be carried as well. The seedborne mycoflora can be identified through the use of seed health tests. The tests are used for several purposes:

•   To assess the incidence of a seedborne pathogen that may affect seed quality.

•   To detect organisms of quarantine concern.

•   To determine seed quality in terms of germinability and or vigor.

•   To determine if pesticide treatment of the seed is necessary.

In this study, efforts were made to compile information on symptoms of 49 grain mold fungi, to detail their morphology, provide quick clues for identification, and describe their importance in terms of diseases, and mycotoxin and metabolite production.

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