Variables associated with Phytophthora and Cylindrocarpon root rots of American ginseng



Quesnel, Francois

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University of Guelph


In 1995 and 1996, researchers at the Pest Management Research Centre in Delhi (Ontario) studied the effect of organic amendments on the survival and pathogenic activity of Phytophthora cactorum and Cylindrocarpon destructans. The objective of this research was to monitor soil chemical and microbiological properties of the different assays conducted in Delhi and correlate them with observed pathogen survival or disease severity. Results have shown that variables linear, quadratic and pairwise interaction effects could explain more than 70% of the variation produced by compost addition. However, those variables could not explain more than 45% of the variation observed among various amendments, suggesting other interacting factors may be at play. A second approach to predicting pathogenic activity was to study carbon substrate utilization patterns of microbial communities from various treatments with the help of Biolog microtitre plates. The method was able to differentiate communities from amended and unamended soil but relating CSU pattern to either suppressiveness or conduciveness of soil was not possible.



American ginseng, root rot, Phytophthora, Cylindrocarpon, organic amendments