核桃炭疽病空间分布格局及抽样技术

Pattern of the spatial distribution and sampling technique of walnut anthracnose fruits

采取随机取样和Iwao回归分析法研究核桃炭疽病病果的空间分布型、抽样技术。结果表明,核桃炭疽病病果的空间分布类型为聚集型分布,病果密度越大,聚集程度越高,分布的基本成分是个体群,这种空间分布是由炭疽病致病菌自身的生物学特性与林间环境因素共同作用的结果。应用Iwao统计方法,确定了理论抽样数和序贯抽样模型。以病果率10%为防治阈值,置信水平为1.96,确定防治上下限方程为T0(n)=10 n±13.4691n(1/2)。

Walnut anthracnose is a kind of serious disease in China walnut orchards and caused losses up to 50%. To carry out control effectively and timely,the spatial distribution pattern and sampling technique were studied through the field investigation using random sampling and Iwao regression analysis.The result showed that the spatial distribution pattern of disease fruits was aggregative distribution. The aggregation intensity increased with the individual density. The individual group was the basic component in the distribution. The aggregation on fruits is due to the biological characteristics of pathogen and environmental factors. At the same time,the optimal theoretical sampling number and sequential sampling model were determined by Iwao regression analysis. When the control threshold of disesased fruit rate was 10%,and the confidence level was 1. 96,the upper limit and lower limit control function of sequential sampling was T0（ n） = 10 n ± 13. 4691n（1/2）.