RESUMO
A study was conducted to determine the occurrence and severity of sorghum downy mildew on three major hosts (maize, sorghum, and Johnson-grass) in Uganda. Five surveys were conducted in four growing seasons, between 1994 and 1995. The disease was encountered in 11 of the 22 districts surveyed. In the majority of the areas, incidence was less than 10%, but it was significantly higher (P < 0.05) in the second season of 1994 than in the first season of 1995. Soil type significantly (P = 0.001) influenced the incidence of sorghum downy mildew, with high incidence being associated with sandy soils, followed by loamy soils, and lowest incidence in clay soils. Incidence, shredding, and oospore production were comparatively higher on sorghum and Johnson-grass than on maize.
RESUMO
Finger millet (Eleusine coracana) is a subsistence crop grown in Sub-Saharan Africa and the Indian Sub-continent. Fusarium species occurring on this crop have not been reported. Approximately 13% of the Fusarium isolates recovered from finger millet growing at three different locations in eastern Uganda belong to Fusarium verticillioides, and could produce up to 18,600 µg/g of total fumonisins when cultured under laboratory conditions. These strains are all genetically unique, based on AFLP analyses, and form fertile perithecia when crossed with the standard mating type tester strains for this species. All but one of the strains is female-fertile and mating-type segregates 13:20 Mat-1:Mat-2. Three new sequences of the gene encoding translation elongation factor 1-α were found within the population. These results indicate a potential health risk for infants who consume finger millet gruel as a weaning food, and are consistent with the hypothesis that F. verticillioides originated in Africa and not in the Americas, despite its widespread association with maize grown almost anywhere worldwide.