Pear rootstocks were tested in an experiment to discover whether any of the rootstocks were resistant to pear root aphid (Eriosonia pyricola). Several different varieties were tested in the process and the author discusses the results of those tests.
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May 1966 Vol. 10, Issue 1 Pages 1, 3
M.N. Westwood H.O. Bjornstad Horticulture Department Oregon State University, Corvallis, OR