First report of Lasiodiplodia brasiliense causing maize stalk rot
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Maize stalk rot can lead to major corn yield losses in Brazil and worldwide. Maize stalks exhibiting tiny black specks or light brown lesions were collected in the city of Luís Eduardo Magalhães. Based on morphological characteristics and molecular assays, the fungus was identified as Lasiodiplodia brasiliense. This is the first report of maize stalk rot caused by L. brasiliense.
KeywordsCorn Zea mays Brazil Botryosphaeriacea
For the pathogenicity test in maize, a toothpick previously immersed in a spore suspension (106 conidia mL−1) was inserted into the third internode (disinfected with 70% ethanol) of plants at the tasseling stage (VT) (Nicoli et al. 2015). Plants of two maize hybrids, P30F53YH and DKB390PRO, were inoculated with CFMS 1342 isolate, in addition to six plants without the fungus (control). In the evaluation performed after 30 days, the plants inoculated with the fungus showed typical SR symptoms (Fig. 1). Morphological features of the fungus re-isolated were identical to those of L. brasiliense used for the inoculation, thus fulfilling Koch’s postulates. The experiments were performed twice, and in both cases, the control plants did not exhibit disease symptoms. Although L. brasiliense has been reported to cause disease in some crops, mainly on fruit plants (Farr and Rossman 2018), to our knowledge, this is the first report of maize SR caused by L. brasiliense in Brazil and in the worldwide. According to IBGE (2018), since 2004 approximately 50% of the area planted with Carica papaya in the Brazilian locality of Luís Eduardo Magalhães has been replaced by maize. Since C. papaya is the main host of L. brasiliense, the present report is of great importance for future research on adaptive behaviour change of L. brasiliense to the new host, as well as in the development of adequate management strategies for controlling this pathogen in maize.
The authors thank CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior and CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico for financial support and Clóvis Geraldo Ribeiro for technical support.
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