Evaluation of foliar diseases for soybean genotypes in the Pan African Soybean Variety Trials

Authors: MURITHI, HARUN - Oak Ridge Institute For Science And Education (ORISE); PAWLOWSKI, MICHELLE - University Of Illinois; HUNDE, DERESSE - Pawe Agricultural Research Center; MALEDE, MOLLA - Pawe Agricultural Research Center; OBUA, TONY - Makerere University; KAMWANA, FLORENCE - Department Of Agricultural Research And Technical Services(DARTS); NUNDWE, MACDONALD - International Institute For Tropical Agriculture; ABUKARI, ISSAH - Savanna Agricultural Research; NJOROGE, JAMES - Kenya Agricultural And Livestock Research Organization; NACHILIMA, CHRISTABEL - International Institute For Tropical Agriculture; CHIGEZA, GODFREY - International Institute For Tropical Agriculture; COYNE, DANIEL - International Institute For Tropical Agriculture; TUKAMUHABWA, PHINEHAS - Makerere University; HARTMAN, GLEN - Retired ARS Employee; Clough, Steven

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2026
Publication Date: 5/2/2026
Citation: Murithi, H.M., Pawlowski, M., Desissa, D.H., Malede, M., Obua, T., Kamwana, F., Nundwe, M., Abukari, I.A., Njoroge, J.N., Nachilima, C., Chigeza, G., Coyne, D.L., Tukamuhabwa, P., Hartman, G.L., Clough, S.J. 2026. Evaluation of foliar diseases for soybean genotypes in the Pan African Soybean Variety Trials. Crop Protection. https://doi.org/10.1016/j.cropro.2026.107666.
DOI: https://doi.org/10.1016/j.cropro.2026.107666

Interpretive Summary: Wide-spread cultivation of soybean on the African continent is continually expanding, and therefore new disease pressures are being revealed. Our team surveyed 14 soybean variety testing locations across six different countries, and we summarized the disease observations. Bacterial diseases were not that damaging nor wide-spread. The fungal disease Cercospora leaf blight was the most predominant, but other fungal diseases such as soybean rust and frogeye leaf spot were also fairly common. Red leaf blotch is another foliar disease of importance in Africa, but we did not review that one as it was recently summarized in another publication. Together, the survey work assists breeders, growers, extension personnel and pathologist in knowing what diseases to expect and prepare for, as well as what to prioritize in developed of disease resistant germplasm or chemical applications.

Technical Abstract: Soybean production is expanding dramatically in Africa due to the growing demand for its nutritional value as livestock feed and foods for human consumption. However, the potential for maximal soybean production within a given African field, is not only limited by few choices of high-quality adapted cultivars, but also by soil quality, weeds, pests and diseases. Soybean diseases cause significant yield losses and may limit the expansion of production in Africa unless they can be managed, such as through host plant resistance. The multi-location Pan African Soybean Variety Trials (PATs) have made it possible to identify disease resistant soybean germplasm that perform well in African environments and also yield well. By surveying 14 PAT locations in six countries: Ethiopia, Ghana, Kenya, Malawi, Uganda, Zambia we evaluated soybean entries adapted to Africa for incidence and severity of foliar diseases. Plants were evaluate during the reproductive growth stages using a visual pre-transformed severity scale. Diseases associated with bacteria (bacterial pustule and bacterial tan spot), fungi (Cercospora leaf blight, soybean rust, red leaf blotch, frogeye leaf spot, and Septoria brown spot), and an oomycete (downy mildew), as well as a disorder of uncertain etiology (mustard spot), were observed in the soybean fields. The severity for the bacterial diseases was generally low. Cercospora leaf blight was the most common disease occurring in 30% of the entries. Differences in severity ratings was noted among some entries at some locations for Cercospora leaf blight, frogeye leaf spot, red leaf blotch and soybean rust. Some entries had lower severity ratings compared to the susceptible checks implying that they may be resistant. The results from this study will help soybean breeders and agronomist in Africa identify promising cultivars and to make more informed decisions on disease management strategies.