Spread Regulation And Control Effect Of Biocontrol Fungus, Puccinia Xanthii Schwein. F. Sp. Ambrosiae-trifidae S. W. T. Batra

The giant ragweed, Ambrosia trifida L., a widely distributed malignance weed in theworldwide, is seriously harmful to agriculture production and human health. Puccinia xanthiiSchwein. f. sp. ambrosiae-trifidae S. W. T. Batra, a host-specific fungicolous of giant ragweed, hasa good control effect on giant ragweed. This paper selected the giant ragweed in Huairou, Beijingas the object to discuss the overwintering in the fields, the natural infection and spreading, and thecontrol efficiency to giant ragweed of P. xanthii Schwein. f. sp. A.-trifidae S. W. T. Batra, and toprovide scientific basis for the application of P. xanthii Schwein. f. sp. A.-trifidae S. W. T. Batra inBeijing. The results as follows:1P. xanthii Schwein. f. sp. A.-trifidae S. W. T. Batra could survive winters in Beijing safely,achieve natural infection and spreading, its biggest daily average propagation distance was70m,the average annual spread distance was2400m, the propagation speed was fast between July andAugust.2The plnts control indices of giant ragweed reduced with increasing distance away from thethe transplanting point, most of which were above0.5. The infection rate of plants was very high,all of them were more than90%. But the plants mortality was low, substantially of which wasunder10%.3The heavier of the infection, the less of the biomass and the fewer of seeds of giantragweed. Once infected, both the biomass and seed of giant ragweed were significantly lower thanthe control.4There were almost no differences of the morbidity among different blocks in the areaswhich were infected in the past year, but the plant height, biomass, seed amount of giant ragweedwere significantly lower than the control. The leaf control indices increased with time, and at theend of the investigation, all of them were above0.7. Both of the plant mortality and leaf mortalitywere more than30%at the end of the investigation. The infection of P. xanthii Schwein. f. sp.A.-trifidae S. W. T. Batra reached its peak from July to August.In this study, the results showed that P. xanthii Schwein. f. sp. A.-trifidae S. W. T. Batra couldfinish its natural circulation in Beijing. P. xanthii Schwein. f. sp. A.-trifidae S. W. T. Batra had agood control efficiency on giant ragweed, so the applied prospects of it is very brightly, and theextensive application of this pathogenic fungi in Beijing is appropriate.