Mancha de pestalotiopsis em helic？nia: caracteriza？？o da doen？a e potenciais fontes de resistência

this study describes a new disease of heliconia, "pestalotiopsis spot", outlines the morphology of the fungus and presents results from the evaluation of resistance of some heliconias to the pathogen. pathogenicity of an isolate obtained from diseased foliage of h. psittacorum x h. spathocircinata cv. golden torch was demonstrated by inoculation of detached leaves and inflorescences of that cultivar of heliconia. susceptibility of ten heliconia cultivars to pestalotiopsis flower and leaf spot was evaluated on freshly cut inflorescences by inoculation of the fungus on previously injured areas of floral bracteas. the fungus had acervular conidiomata, epidermal to subepidermal, fusiform conidia, straight to slightly curved, measuring 21.0-26.5 x 6.5-8.5 μm, four septates with the three median cells dark brown, three to five filiforme apical appendages, 8-15 x 1.0 μm and a basal pedicel, 5.0 x 1.0 μm. the fungus was identified as pestalotiopsis pauciseta. inoculation of detached leaves and flowers by laying the culture disk of p. pauciseta over previously damaged tissues has demonstrated that the fungus is the etiological agent of this new heliconia disease. evaluation of resistance to pestalotiopsis spot showed that h. rostrata and h. caribeae x h. bihai cv. jacquinii were the most resistant among the tested cultivars. no lesions were produced on h. rostrata after inoculation. h. stricta cv. las cruzes was the most susceptible, followed by h. wagneriana. this is the first record of pestalotiopsis spot in heliconia and also the first report of heliconia resistance to this disease.