In 1960 a project was started to identify pear rootstocks resistant to pear decline, a virus that negatively impacted Oregon's pear orchards. Several viable clonal rootstocks were found and are discussed in regards to hardiness and resistance to other pear issues.
To view article, click on attachment link above.
April 1967 Vol. 11, Issue 1 Page 3
M.N. Westwood Horticulture Department Oregon State University, Corvallis, OR