Soybean production in eastern and southern Africa and threat of yield loss due to soybean rust caused byPhakopsora pachyrhizi

Abstract

Soybean is a major source of oil and proteins worldwide. The demand for soybean has increased in Africa, driven by the growing feed industry for poultry, aquaculture and home consumption in the form of processed milk, baked beans and for blending with maize and wheat flour. Soybean, in addition to being a major source of cooking oil, is also used in other industrial processes such as in the production of paints and candle wax. The demand for soybean in Africa so far outweighs the supply, hence the deficit is mainly covered through imports of soybean products such as soybean meal. The area under soybean production has increased in response to the growing demand, a trend that is expected to continue in the coming years. As the production area increases, diseases and insect pests, declining soil fertility and other abiotic factors pose a major challenge. Soybean rust disease, caused by the fungus Phakopsora pachyrhizi, presents one of the major threats to soybean production in Africa due to its rapid spread as a result of the ease by which its spores are dispersed by the wind. Disease control by introducing resistant soybean varieties has been difficult due to the presence of different populations of the fungus that vary in pathogenicity, virulence and genetic composition. Improved understanding of the dynamics of rust ecology, epidemiology and population genetics will enhance the effectiveness of targeted interventions that, in turn, will safeguard soybean productivity.

Halotolerant rhizobacteria Pseudomonas pseudoalcaligenes and Bacillus subtilis mediate systemic tolerance in hydroponically grown soybean (Glycine max L.) against salinity stress

“…Soybean is cultivated worldwide due to its nutritional value and oil yielding characteristics [9]. It has a wide range of adaptations but as salt sensitive crop show limited seed germination, post germination growth, photosynthesis and yield reduction upto 40% due to salinity stress [10].…”

Spray volume deposits and fungicide efficacy on soybean rust (Phakopsora pachyrhizi)

“…2) probably contributed to reduce seed weight. The SBR disease reduces soybean yield in Brazil and other countries around the world (Scherm et al, 2009;Costa et al, 2015;Murithi et al 2016). A study published by Scherm et al (2009), showing a quantitative review of 71 fungicide efficacy trials conducted in Brazil from 2003/2004 to 2006/7, verified a yield reduction average of approximately 22% relative to the treatment without fungicide application.…”

“…Soybean [Glycine max (L.) Merrill] is an economically important crop cultivated by producers all over the world (Murithi et al, 2016). Soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi Syd & P.…”

“…This is not only because the disease spreads rapidly, but also because it can cause significant yield reductions where management practices are poor (Prado et al, 2015). Despite many studies on the development of soybean cultivars resistant to P. pachyrhizi (Langenbach et al, 2016;Vuong et al, 2016;Childs et al 2018), control has been difficult due to the variability and dynamic plasticity of the rust population, varying in virulence and genetic composition (Murithi et al, 2016). One of the most effective management strategies to suppress SBR severity and to reduce yield loss is the application of sequential fungicides (Scherm et al, 2009;Costa et al, 2015;Prado et al, 2015).…”

Biochemicals Associated With Callosobruchus Chinensis Resistance in Soybean.

“…However, it is mostly cultivated by small-scale farmers in other parts of Africa where it is planted as a minor food crop among sorghum, maize, or cassava. In Africa, Uganda is the second largest consumer of soybean following Nigeria (Murithi et al, 2016). Soybean is among the major industrial, feed and food crops grown in every continent (Dugje et al, 2009).…”