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The taxonomy of the genus Colletotrichum has undergone various changes. These alterations arise from the use of modern molecular tools. Currently, Colletotrichum species are grouped into complexes. Species of Colletotrichum associated with diseases in lima bean have been investigated very little. In Brazil, anthracnose in lima bean has often been associated with Colletotrichum truncatum, but only morphological characteristics have been used for identification purposes. In this study, samples of lima bean with symptoms of spots on the leaves and pods have been collected in Piauí and Alagoas states. Comparisons of morphological characteristics revealed nine isolates with cylindrical or curved conidia. The ITS region and partial sequences of GAPDH, β-tubulin and Actin regions were amplified by PCR, sequenced and submitted to multilocus phylogenetic analysis. The isolates analyzed grouped with reference specimens from Colletotrichum truncatum, C. cliviae and C. fructicola. All isolates were pathogenic to 25-day-old lima bean seedlings. Therefore, this work confirms the pathogenicity of C. truncatum to lima bean and for the first time records the occurrence of C. cliviae and C. fructicola as pathogens of this host in Brazil.

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The fungi Colletotrichum truncatum and Macrophomina phaseolina are among the main pathogens associated with lima bean seeds in Brazil, and they are the causal agents of anthracnose and charcoal rot, respectively. The aim of this study was to verify the seed-seedling transmission of C. truncatum and M. phaseolina in artificially inoculated lima bean seeds. Potato-dextrose-agar (PDA) media with different hydric potentials were obtained after the addition of mannitol. Isolates of C. truncatum and M. phaseolina were peaked to these media. Forty grams of seeds were distributed over the fungal mycelium, remaining there for different exposure periods, as a function of each treatment: T1: 0.0 MPa without inoculum for 48 h; T2: 0.0 MPa for 48 h; T3: -0.2 MPa for 48 h; T4: -0.4 MPa for 48 h; T5: -0.6 MPa for 72 h; T6: -0.8 MPa for 96 h and T7: -1.0 MPa for 120 h. The seeds were incubated at 25 ºC under a 12-hour photoperiod. Germination in a paper roll, emergence of seedlings in sand and seed health in PDA were evaluated. T4 provided the best conditions to temporarily prevent seed germination, promoting a greater incidence of seeds infected by C. truncatum and a greater percentage of diseased plants. M. phaseolina reduced seed germination, independently of the inoculated treatment. Both fungi were transmitted from the seeds to the seedlings of lima bean, causing symptoms in various aerial parts. C. truncatum and M. phaseolina transmission rate was 83.1% and 76.46%, respectively.