Evaluation of foliar diseases for soybean entries in the Pan-African Trials in Malawi and Zambia

Authors: NACHILIMA, CHRISTABELL - International Institute For Tropical Agriculture; CHIGEZA, GODFREE - International Institute For Tropical Agriculture; CHIBANDA, MWILA - Seedco; MUSHORIWA, HAPSON - Seedco; DIERS, BRIAN - University Of Illinois; MURITHI, HARUN - Oak Ridge Institute For Science And Education (ORISE); Hartman, Glen

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2020
Publication Date: 3/2/2020
Citation: Nachilima, C., Chigeza, G., Chibanda, M., Mushoriwa, H., Diers, B., Murithi, H., Hartman, G.L. 2020. Evaluation of foliar diseases for soybean entries in the Pan-African Trials in Malawi and Zambia. Plant Disease. 104(8):2068-2073. https://doi.org/10.1094/PDIS-12-19-2617-SR.
DOI: https://doi.org/10.1094/PDIS-12-19-2617-SR

Interpretive Summary: Soybean production has expanded worldwide including countries in Sub-Saharan Africa. Soybean production in Africa is considered important to farmers with smaller hectarage. Several national and international agencies and research groups have partnered to improve overall performance of soybean breeding stocks and have introduced new germplasm from Brazil and the USA with the goal of developing new high-yielding cultivars. These trials are known as the Pan African Soybean Variety Trials and the entries come from both private and public breeding programs. The objective of this research was to evaluate entries in the trials that include commercial cultivars or advanced experimental lines for the incidence and severity of foliar diseases. All trials were planted in December 2018 with six located in Zambia and one in Malawi. Plants were evaluated during the reproductive growth stages using a visual pre-transformed severity rating scale. Foliar disease ratings were recorded for three bacterial diseases, six fungal diseases, one oomycete and viruses. The overall occurrence of most of the diseases were high except for soybean rust and target spot. In conclusion, this work provides a bookmark for the current status of soybean diseases in Sub-Saharan Africa and a framework for further evaluation of soybean diseases in more Pan African Soybean Variety Trial locations. This information is important to soybean researchers worldwide as well as breeders, pathologists, and farmers in Africa.

Technical Abstract: Soybean production has expanded worldwide including countries in Sub-Saharan Africa. Several national and international agencies and research groups have partnered to improve overall performance of soybean breeding stocks and have introduced new germplasm from Brazil and the USA with the goal of developing new high-yielding cultivars. Part of this effort has been to test improved soybean lines/cultivars accumulated from private and public sources in multilocational trials in Sub-Saharan Africa. These trials are known as the Pan African Soybean Variety Trials and the entries come from both private and public breeding programs. The objective of this research was to evaluate entries in the trials that include commercial cultivars or advanced experimental lines for the incidence and severity of foliar diseases. All trials were planted in December 2018 with six located in Zambia and one in Malawi. Plants were evaluated during the reproductive growth stages using a visual pre-transformed severity rating scale. Foliar disease ratings were recorded for three bacterial diseases, six fungal diseases, one oomycete and viruses. The overall occurrence of most of the diseases were high except for soybean rust and target spot, which were only found at two and one location, respectively. However, disease severity was generally low although there were differences in disease severity ratings among the entries at some of the locations for brown spot, downy mildew, frog-eye leaf spot, red leaf blotch, and soybean rust.