Abstract:

The damage and loss caused by citrus huanglongbing in citrus orchards. in Taizhou city had become more and more serious since 2002. Occurrence of citrus huanglongbing in citrus orchards were investigated from 2004 to 2009 in order to reveal their distribution and population behaviour. Three methods of aggregated indices and Iwao’s way (regressive relation by M*-m) and power law of Taylor were used to test the spatial disritbution pattern of citrus huanglongbing in citrus orchards. The results showed the population of citrus huanglongbing belong to the pattern of aggregation distribution. It was tested by Blackith’s method ,when m＜2.1184, their aggregation was caused by some environmental factors sush as climate, planting, and growth and so on; when m≥2.1184, their aggregation was caused by their behaviour and environmental conditions. Based on this distribution pattern the model for determining the optimum theortical sampling number and the optimum sequential sampling are proposed. The model are as follows: n=(1/D)2?[1/m+0.6761] and Tn=1.831 /[D02-0.1581 /n].