福建平和琯溪蜜柚炭疽病病原OA

The pomelo(Citrus maxima)is one of the most important cultivated fruit trees in the genus Citrus of the Rutaceae.It has a long cultivation history and great economic value in China.In recent years,a pomelo disease locally called"red flower blight"has been discovered in Pinghe County of Fujian Province,the largest pomelo production area in China.It could cause new shoot blight,rotting and reddening of the flower buds and petals of the variety"Guanximiyou",ultimately leading to flower and fruit drop.In the seriously infected orchards,over 80%of fruitlets dropped.The disease has been spreading from mountainous areas to plains,with affected orchard areas expanding year by year.Based on the disease symptoms,it was speculated to be post-bloom fruit drop(PFD),a citrus disease reported in South America and Florida.However,there are still some differences in host range and infected organs between this disease and PFD.From the infected specimens,orange powdery substances and conidia resembling to Colletotrichum acutatum were observed.Five single-spore isolates showing identical colonial morphology were obtained.Based on the morphological characteristics,multi-loci(ACT,CHS-1,GAPDH,HIS3,ITS and TUB2)phylogenetic analysis,and pathogenicity test,the causal agent was identified as C.fioriniae in C.acutatum species complex.Given that this disease has only been found on pomelo so far,affecting not only flowers but also young shoots and fruits,and the pathogen differs from that of PFD and common anthracnose,this disease is named as"pomelo anthracnose".This is the first report of C.fioriniae as a pathogen infecting citrus and causing anthracnose.The accurate identification of the pathogen provides a scientific basis for precise control of the disease.