柑橘黄龙病老龄果园发病力与时序发生规律研究

Citrus Liberobacter Asiaticum Morbidity and Timing Patterns in Old Orchards

为揭示柑橘黄龙病自然感染年序病情发生规律,以提高监测预警防控水平提供科学依据,笔者于2002—2015年在天然隔离屏障良好的一个老龄果园开展柑橘黄龙病自然感染发病危害研究,在初入侵果园采取3个重复样地定点定株发病扩散危害系统调查。坚持14年试验结果表明:柑橘黄龙病自然感染发病力以自然感染发病4~5年后为最强盛,其发病力可达年新发病率10%~15%,较其初发病力增强2~3倍;其当年新发病率消长呈"M型"曲线变化规律:第1自然感染发病显症高峰一般为初次入侵后的第5年前后,峰期一般为2~3年;第2个自然感染发病显症高峰为初次入侵后的第9年前后,峰期一般为1~3年,两峰之间为高位波动变化动态。老龄果园黄龙病积年发病呈Logistic曲线上行变化轨迹,其年序数值化变化模型为Q=85.8144/(1+EXP(4.0063-0.5837N))(n=14,r=0.9941^(**)),其自然感染扩散大周期为15年(其中核心为害周期10年左右)。运用这些变化规律,对提升老龄果园黄龙病监测预警防控具有十分重要的指导意义。

To reveal natural occurrence of citrus liberobacter asiaticum and provide a scientific basis for monitoring, preventing and controlling the disease, a study was made from 2002 to 2015 on natural infection morbidity in a citrus orchard with good natural isolation barrier by taking three sample plots to find out the onset and diffusion of the disease. The fourteen-year study showed that citrus liberobacter asiaticum morbidity was the most powerful four or five years after the natural infection, and reached 10% to 15% yearly, which increased by two to three times compared with its early incidence force. Its varying curve of occurrence acted as an ＂M＇. The first peak symptomatic appearance of natural infection was around the 5＇h year after the first incidence and the second happened 9 years later or so. Generally, the peak period lasted 1 to 3 years and the change between the two peaks fluctuated with high volatility. The occurrence regularity of citrus liberobacter asiaticum morbidity showed an upward trajectory in Logistic curve and its chronological value change model was：Q=85.8144/（1＋EXP（4.0063-0.5837N））（n=14,r=0.9941-（＊＊））, and its big cycle of natural infection spreading was 15 years （including core harm period of 10 years or so）. This change patterns could be of guiding significance to monitoring, preventing and controlling citrus liberobacter asiaticum in old orchards.