落花落果对荔枝园霜疫霉初侵染源萌发的作用

Effect of dropped-blossoms and fruits on primary inoculum source germination on litchi downy blight in litchi orchard

为了明确落地小花、小果对荔枝园霜疫霉初侵染源萌发的作用和该病害流行的起点,采用树盘下覆地膜的方法,2011～2013年连续3年在果园检测落地小花、小果和树上小花、小果霜疫霉感病率.结果表明,树盘下的越冬菌源是霜疫霉病主要初侵染源,覆地膜可以隔离树盘下初侵染源对落地小花、小果的侵染,落地小花、小果与树盘下越冬菌源的接触是荔枝霜疫霉病在果园流行的起点,从而间接证明了荔枝园霜疫霉初侵染源萌发的关键物候期为开花期到第2次生理落果期.

In order to confirm effect of dropped-blossoms and fruits on primary inoculum source germination of litchi downy blight and beginning point of the disease epidemic, incidence of Peronophythora litchii on dropped-blossoms and fruits were investigated through covering with plastic film under tree-disk from 2011 to 2013. The results showed that overwintering inoculum under the tree-disk could be a major primary inoculum source of the pathogen and mulch with plastic film could close off dropped-blossoms and fruits infected by P. litchii. The epidemic of the disease began in contact between dropped-blossom-fruit and primary inoculum source under tree disk. Furthermore, it showed that the key phenophase of primary inoculum source germination on litchi downy blight in orchard lasted from anthesis to the second physiological drop, which provided new strategies for controlling litchi downy blight caused by P. litchii.