Influence of Harvest Date on Bull's Eye Rot of 'Cripps Pink' Apple and Control Chemical Strategies.

ABSTRACT

The influence of four different harvest times on the bull's eye rot of 'Cripps Pink' apple caused by Neofabraea spp. was investigated in two orchards harvested at four different times. In addition, a control strategy based on chemical treatments performed in preharvest or postharvest was evaluated. Regression analysis between harvest time and disease incidence revealed high r2 values (>0.75). All preharvest fungicide treatments significantly (P < 0.0085) reduced the bull's eye rot incidence; however, thiophanate-methyl (achieving >87% control) was more effective than a mixture of pyraclostrobin and boscalid (<80.7%) or fludioxonil (<57.6%), in all trials. Compared with nontreated control fruit, a postharvest treatment with the ethylene inhibitor 1-methylcyclopropene (1-MCP) halved the incidence of infection in three of four experiments. However, a combination of two preharvest treatments with a mixture of pyraclostrobin plus boscalid and one postharvest 1-MPC treatment suppressed bull's eye rot to a significantly (P < 0.00001) greater degree (achieving >87.5% control) than the single treatments with pyraclostrobin and boscalid (<65%) and 1-MCP (<80%) tested alone.