First report of Diaporthe kongii causing foot rot on sweet potato in Brazil.
Sweet potatoes (Ipomoea batatas) are one of the most important crops in the world, especially in developing countries. Foot rot of sweet potato is one of the major diseases responsible for economic losses in the crop, making some areas of production unviable. Reports show that foot rot of sweet potato causes losses of 80% in the productivity of the cultivar CO-BRANCA in the area. Postharvest rot may occur on storage roots, making them unviable for commercialization. In May 2017, symptoms similar to foot rot, such as brown to black lesions on roots and yellowing of leaves, were observed in plants and roots of CO-BRANCA in Belém de Maria, Pernambuco, Brazil, with a disease incidence of 50%. Based on morphological characteristics, molecular data (maximum likelihood and Bayesian inference of the sequences of nrITS and EF1-α regions) and pathogenicity tests, the causal agent was identified as D. kongii. This fungus was previously reported in association with sunflower, peanut, and Portulaca Grandiflora in Australia. This is thought to be the first report of D. kongii causing disease on sweet potatoes in the world.