Pattern of spatial distribution and sampling technique of winter jujube black spot

Black spots on winter jujube constitute the most significant threat to the safe production of winter jujube. In this paper, the pattern of spatial distribution, sampling technique and influencing factors of black spots in winter jujube were analyzed using Taylor’s power law, Iwao’s distribution function, and six aggregation indices. The results show that the pattern of spatial distribution of black spot in fruits and leaves of winter jujube is aggregative distribution. The basic component of the distribution is the individual colonies. The degree of aggregation increases with the increasing of individual density. The aggregation on fruits and leaves is due to the disease behavior and other environmental factors. Using the parameters a and b in Iwao’s m*-m regression equation, the optimal and sequential sampling numbers are determined.