Biological control of phacidiopycnis rot in 'd'Anjou' pears.

摘要

Phacidiopycnis rot, caused by Phacidiopycnis piri, is a recently reported postharvest fruit rot disease of pears (Pyrus communis) in the US, and a major disease of 'd'Anjou' pears grown in Washington State. Phacidiopycnis rot can originate from infection of wounds on the fruit. In this study, two biocontrol agents, BioSave (a Pseudomonas syringae strain) and Cryptococcus laurentii strain 87-108, were compared with the conventional fungicide thiabendazole (TBZ) for their efficacy in controlling Phacidiopycnis rot. 'D'Anjou' pear fruit were surface disinfected, wounded with a finishing nail head, treated with one of the biocontrol agents or TBZ, and inoculated with conidial suspension of P. piri. An untreated control where fruit were inoculated with the pathogen was also included in the trial. The experiment was conducted twice using fruit from different orchards where no fungicides were used. Each treatment contained four 20-fruit replicates. Inoculated fruit were placed on fiber fruit trays wrapped with perforated bags and stored in cardboard boxes at 0 degrees C for three months, at which time decay was assessed. Over 92% of the fruit in the untreated control developed Phacidiopycnis rot. BioSave and C. laurentii significantly reduced incidence of Phacidiopycnis rot by 96-98 and 38-45%, respectively, compared with the control. BioSave was more effective than C. laurentii. No decay was observed on TBZ treated fruit, but there was no statistical difference in decay incidence between BioSave and TBZ treatments. The results suggest that BioSave is effective in controlling Phacidiopycnis rot originating from wound infections by P. piri and can provide a level of control of Phacidiopycnis rot comparable with that of TBZ.