Boeremia exigua causing leaf spots on sweet potato in Brazil.
2020
COLMÁN, A. | LIMA, I. de M. | COSTA, H. | BARRETO, R. W. | A. COLMÁN, UFV; Inorbert de Melo Lima, Incaper; Helcio Costa, Incaper; R. W. Barreto, UFV.
In what is a first for the world, leaf spot disease of sweet potato, caused by Boeremia exigua, is reported in Brazil. Identity of the fungus was confirmed by a combination of molecular and morphological data. Koch s postulates were fulfilled with a selected isolate of the fungus obtained from Santa Maria do Jetibá, state of Espírito Santo, Brazil. Ipomoea batatas (Convolvulaceae) - sweet potato - is the sixth most important food crop worldwide (CIP 2020). Several diseases are limiting factors for this crop, including field and storage diseases (Clark et al. 2013). In Brazil, sweet potato has lost some of its former importance because of changes in the consumer s habits but still remains one of the top vegetables in Brazilian agriculture (Silva et al. 2008). These authors listed several fungal diseases that occur on sweet potato in Brazil, but considered that damage to the crop by fungal diseases is normally small. In June 2015, sweet potato plants bearing severe leaf spot damage were observed in a plantation in the municipality of Santa Maria de Jetibá (state of Espirito Santo, Brazil). Lesions were initially circular but became irregular, slightly sunken and zonate, dark brown, surrounded by a chlorotic halo, coalescing and leading to a blight of part or entire leaves (Fig. 1a). Older lesions often became torn in their central parts. Numerous, black dots were repeatedly seen immersed in the necrosed tissues when viewed using magnifying lens. Primeiro registro no Estado de Boeremia exigua.
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