Occurrence and Epidemic Regularity of Wheat Stripe Rust in Nanchong City of Sichuan Province

In order to realize monitoring and early warning and comprehensive management of wheat stripe rust and to reduce its occurrence in Nanchong City,the occurrence and epidemic regularity of wheat stripe rust in Nanchong was studied by system monitoring and general survey,resistance identification,physiological race monitoring and meteorological data analysis. The initial occurrence location and spreading pathway of Puccinia striiformis f. sp. tritici( Pst) were first verified;there were two infection peaks of wheat stripe rust in Nanchong and one to three epidemic peaks in fields,in which the occurrence area of the first epidemic peak played a pivotal role in disease prevalence in that year; the cumulative occurrence area in late January was positively correlated with annual occurrence area,with the correlation coefficient of 0. 769; the prediction model for infected field rate,diseased plant rate and annual occurrence area was established. The internal reason for heavy occurrence and prevalence of wheat stripe rust in Nanchong was the decline or loss of wheat resistance against stripe rust,as well as the appearance of physiological races of Pst,which later became dominant races. Large fluctuation of temperature in warm winter and spring and more fog and dew days were external reasons responsible for prevalence of stripe rust. From 2002 to 2014,the accuracy rate of short-term prediction of wheat stripe rust reached 100%,while that of medium-term and long-term prediction reached over 98% and 95%,respectively,5%- 15% higher than that of the years before 1998.