Abstract:
Epidemics of papaya ringspot disease (PRV)were monitored in fields in Guangzhou in 1988 and 1989.It was shown by analyzing the data of seasonal dynamics of disease develop-ment that the greatest rate of disease incidence increase appeared in early september.During the epidemic season, alate populations occurred in three peaks:early June,mid-August and mid-October.Ten to twenty days after each peak,there was a peak ofdisease incidence development.The seasonal dynamics of disease development and the growthand decline of the aphid populations were correlated to wind velocity,temperature and hu-midity.By comparing the fitness of three epidemic models (Logistic,Gompetz and Weibull)to the data of disease incidence,it was found that the disease development was best des-cribed by Gompertz model.With the equations of diseae progress,analyzing every parameterand calculating the number of days for disease to reach the incidence of 5%, 50%,90%,and99%,it was found that the disease epidemic pattern of papaya ringspotbelonged to the type of low virus source,low rate of infection and long epidemic pe-riod.By artificial inoculation with aphids(Myzus persicae),two models for infectiousand apparition dynamics of the disease were developped; both of them showed thatWeibull equation best described the dynamic of latent and incubation period,whichwere demonstrated to be about eleven and seventeen days respectively.