Physiological Adaptability of Lasiodiplodia spp. from Acerola in a Semi-Arid Region

Abstract

Drop dieback caused by fungi of the genus Lasiodiplodia is an important disease of acerola in the semi-arid region of Brazil. Information on the influence of fungicides on Lasiodiplodia species of acerola is unknown. Thus, the ED50 (effective dose to reduce mycelial growth by 50%) of seven Lasiodiplodia species was estimated in vitro for the fungicide thiophanate-methyl. The optimal temperature, salinity, and adaptability components were also measured for the species. The ED50 for the MBC fungicide ranged from 0.742 to 2.702 µg.mL-1. Among the seven species studied, L. pseudotheobromae and L. iraniensis showed the greatest sensitivity to thiophanate-methyl, followed by L. brasiliense, L. gonubiensis, L. euphorbicola, and L. hormozganensis, which, on a relative scale of sensitivity, are moderately sensitive species, and finally, L. theobromae was the least sensitive species to the fungicide. At extreme temperatures (10 and 40°C), the Lasiodiplodia species did not develop. The optimal temperature for mycelial growth of the Lasiodiplodia species was... The temperature of Lasiodiplodia isolated from acerola trees was 25.3°C. For the species *L. brasiliense*, there was an indication of adaptability costs. This species, moderately sensitive to thiophanate-methyl, showed greater mycelial growth under high saline stress conditions. The other species did not show adaptation costs.