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流行过程一般可分为三个阶段:(1)中心病株(区)阶段;(2)病害增长蔓延阶段;(3)病情下降消退阶段。病害在不同的年份和地区按三种方式发展:(1)一开始发病即较普遍,后转严重,到达高峰后逐渐下降消退;(2)以中心病株(区)为始点,使林段或大区病情逐渐加重,后转消退下降;(3)病害出现很迟,零星分散,没有中心病株(区),也没有大区流行高峰期。 20多年的资料研究分析结果表明,冬春温度,抽叶期长短,病害流行始点期出现迟早,越冬菌量,嫩叶期雨日等,与病害流行关系较密切。冬春温度是病害流行的主导因素。低温阴雨天气是病害发展的综合有利条件。温度主要是通过落叶、抽叶物候影响病害的流行强度。分析广东垦区的白粉病发生与气候的关系,发现有四种流行气候型:(1)冬春温暖流行型,(2)冬暖春凉流行型,(3)冬冷春凉流行型,(4)冬春干旱流行型。根据海南岛、粤西垦区各地历年病害的流行频率和流行强度,气候、物候特点,可将广东垦区划分为三个流行区:(1)常发区,(2)易发区,(3)偶发区。
The epidemic can generally be divided into three stages: (1) the center diseased (area) stage; (2) disease growth and spread stage; (3) the decline of the disease subsided stage. Disease in different years and regions in three ways to develop: (1) the onset of the disease is more common, severe after the turn, and gradually decline after reaching the peak receded; (2) the center of the diseased (district) as the starting point, so that forest Or area gradually aggravated, after the transfer to decline; (3) the disease appeared late, sporadic scattered, no central diseased (area), there is no peak epidemic area. More than 20 years of data research and analysis results show that the winter and spring temperature, the length of the pumping stage, the early onset of disease appear sooner or later, the amount of overwintering bacteria, rainy days and other young leaves, and disease epidemic more closely. Winter temperature is the dominant factor in the epidemic. Cold and rainy weather is a comprehensive favorable conditions for disease development. Mainly through the leaves of the temperature, pumping leaves phenology affect the prevalence of disease intensity. Analysis of the relationship between the incidence of powdery mildew and climate in Guangdong reclamation area found that there are four popular climatic types: (1) winter and spring warm popular type, (2) cold winter and spring cold type, (3) winter and cold spring cold type, ( 4) Drought spring popular type. According to the epidemic frequency, epidemic intensity, climatic and phenological characteristics of the disease over the years in Hainan Island and western Guangdong reclamation area, Guangdong reclamation area can be divided into three popular areas: (1) frequent occurrence, (2) easy onset, (3) Sporadic area.