Characterization of Neofabraea actinidiae and N-brasiliensis as causal agents of apple bull's-eye rot in southern Brazil

摘要

The causal agents of apple bull's-eye rot in southern Brazil have recently been described as Neofabraea actinidiae and N. brasiliensis. Isolates of both species were evaluated for response of mycelial growth index (MGI) to different temperatures, enzyme production, mycelial growth inhibition and effective concentrations (EC50 and EC100) of the fungicides triflumizole, pyrimethanil and thiophanate methyl, as well as aggressiveness on fruits of Fuji' hybrid and Pink Lady'. There was significantly lower mycelium growth in N. brasiliensis compared with N. actinidiae at all temperatures tested. Neither species grew at 3 and 32 degrees C. There were minor differences in production of enzymes in the two species, with all N. brasiliensis isolates showing no production of pectolyase at pH 7. The lowest EC50 and EC100 values were observed with thiophanate methyl. In general, 'Fuji' fruits were more susceptible to Neofabraea infection and had larger lesions, while N. brasiliensis isolates showed greater aggressiveness on Fuji' hybrid and Pink lady' fruits compared with N. actinidiae.