Study On The Incidence And Pathogen Of Peach Tree Gummosis

Peach tree gummosis does great harm to peach trees all over the world, and the injury is especially serious in the regions where it often rains. Peach is one of the main fruit trees cultivated in Chongqing, where the highest incidence of gummosis is over 90% according to some preliminary investigation. In this dissertation, we report the incidence and factors of peach tree gumossis in this area, the isolation of possible pathogen, its pathogenicity and biological characters. The main results are as follows.1. Symptoms of peach tree gummosis in ChongqingFor young trees, gummosis mainly appears on the trunks, for old ones, practically on all the trunks, branches and twigs, and also sometimes on fruits. Gumming is originated from both lenticels and wounding. For the gumming of lenticels, symptoms include the appearance of swelling or watery spot, after the swelling break, gumming with the color changing from colorless fluid to brown solid. The disease outbreaks when the rainfall is enough, especially after a long period of drought.2. Incidence of peach tree gummosis and its change trend within the yearPeach tree gummosis becomes widespread and severity in all the investigated orchards. The highest incidence and disease contamination index are 95.9% and 67.7, respectively, with corresponding average of 66.8% and 41.1. The results of investigation in the same 30 peach trees in...