1997 Volume 41 Issue 2 Pages 105-107
To test the JANZEN hypothesis, I investigated the proportion of injuries caused by Prociphilus oriens MORDVILKO on Fraxinus lanuginosa KOIDZ. saplings planted with mature host trees in Sapporo, Japan, in 1993. There is a significant negative relationship between the proportion of injuries caused by P. oriens and the distance from mature trees, supporting part of the JANZEN hypothesis.