Disease : a constraint to sorghum production in Honduras

As a result, sorghum is left vulnerable to several diseases. This report examines the major 21 diseases which have constrained sorghum production in Honduras. The effect of Acremonium wilt on sorghum production was studied through paired-plant comparisons. Healthy plants produced 50% more grain than diseased ones. The same technique served to study the effect of maize dwarf mosaic, which caused a 54% loss in production. Sorghum downy mildew was studied by using near- isogenic populations; up to a 44% yield difference in these populations was due to this disease. Gray leaf spot was shown to cause 20% yield loss in a study comparing fungicide protected and unprotected plots. In a similar test, zonate leaf spot caused a 14% yield reduction. Disease severity data collected from small farmer fields was used to develop a mathematical model in another study, with which sorghum yields were estimated at given levels of disease severities. This study included gray leaf spot, oval leaf spot, rust, and covered smut. Yield losses of 15%, 5%, and 3% were estimated for the first three of these diseases, respectively. Disease severities were also studied under different cropping systems. It was possible to evaluate a number of sorghum accessions planted at various locations throughout Honduras during the time of these studies. Sources of resistance for six diseases were identified. These were recommended as breeding stock in an sorghum improvement program under way, cosponsored by INTSORMIL and the Ministry of Natural Resources of the Honduran government. (Author abstract, modified)