Efeitos de ferimento, umidade e temperatura na virulência de espécies de Lasiodiplodia em frutos de manga

Abstract

Dieback and stem-end rot, caused by species of Botryosphaeriaceae, are important diseases of mango in the Brazilian Northeast. These diseases limit the production and drastically reduce fruit quality, directly affecting exports. In this study, was investigated the effects of wound, humidity and temperature in virulence of five Lasiodiplodia species prevalent in the orchards of northeastern Brazil (L. hormozganensis, L. iraniensis, L. pseudotheobromae, L. theobromae and L. viticola). Lasiodiplodia hormozganensis, L. pseudotheobromae and L. theobromae did not induce symptoms in non-wounded fruits, but all Lasiodiplodia species induced symptoms in wounded fruits. There were differences between species in relation to virulence levels both in the absence and in the presence of wound. The wound age in fruits influenced the virulence of Lasiodiplodia species of all species has expressed increased virulence when inoculated immediately after the wound, reducing the virulence with increasing wound age. Lasiodiplodia pseudotheobromae was the most sensitive species to the wound age. The high relative humidity length influenced the virulence of the Lasiodiplodia species, with an increase in virulence with the lifting of the period under high humidity. Lasiodiplodia hormozganensis, L. iraniensis and L. theobromae induced symptoms in the absence of high humidity. The virulence of Lasiodiplodia species was significantly influenced by the time interval between the inoculation and beginning of high relative humidity. All species expressed increased virulence when exposed to high relative humidity immediately after inoculation and decreased virulence with increasing time interval to beginning of high humidity. Lasiodiplodia iraniensis and L. viticola were the species most sensitive to the delay in onset of high relative humidity. No Lasiodiplodia species induced symptoms in fruit stored at 5 ° C and only L. pseudotheobromae induced symptoms at 10 ° C. There was no significant difference between species in relation to the optimum temperature for maximum virulence expression, ranging between 29.6 and 31.3 ° C. In most experiments, the increased virulence was demonstrated by L. iraniensis while L. viticola was less virulent.