Mathematical Analysis and Modeling of Epidemics of Rubber Tree Root Diseases: Probability of Infection of an Individual Tree

Author： Chadoeuf J. Joannes H. Nandris D. Pierrat J. C.

Publisher： Society of American Foresters

ISSN： 0015-749X

Source： Forest Science, Vol.34, Iss.4, 1988-12, pp. : 831-845

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Abstract

The spread of root diseases in rubber tree (Hevea brasiliensis) due to Rigidoporus lignosus and Phellinus noxius was investigated epidemiologically using data collected every 6 months during a 6-year survey in a plantation. The aim of the present study is to see what factors could predict whether a given tree would be infested at the following inspection. Using a qualitative regression method we expressed the probability of pathogenic attack on a tree in terms of three factors: the state of health of the surrounding trees, the method used to clear the forest prior to planting, and evolution with time. The effects of each factor were ranked, and the roles of the various classes of neighbors were established and quantified. Variability between successive inspections was small, and the method of forest clearing was important only while primary inocula in the soil were still infectious. The state of health of the immediate neighbors was most significant; more distant neighbors in the same row had some effect; interrow spread was extremely rare. This investigation dealt only with trees as individuals, and further study of the interrelationships of groups of trees is needed. For. Sci. 34(4):831-845.