Tree survival beyond 2 years of intergeneric pear/apple graft combinations depended on the scion cultivar, the use of ‘Winter Banana’ apple interstock, and the specific rootstock. Trees with ‘Cornice’ scion and ‘Winter Banana’ interstem (on all six stocks) had higher survival (27%) after 11 years than those with ‘Bartlett’ scion (12%). No ‘Cornice’ tree on apple rootstock survived without the ‘Winter Banana’ interstem. Tree survival with ‘Winter Banana’ interstem after 11 years was 73% on M.26, 14% on M.7 and M.9 EMLA, 7% on MM.106 and MM.111, and 0% on M.9. Only trees of ‘Bartlett’ and ‘Cornice’ on M.26 and ‘Cornice’ on M.7 with ‘Winter Banana’ interstems produced fruit through the 11th year. Tree size ranged from 10% of standard for ‘Bartlett’ on M.26 to 25% for ‘Cornice’ on M.7 with the ‘Winter Banana’ interstem. Incompatability suppressed mainly foliar N and Zn but, to a degree, also P, Ca, and B.
Received for publication 7 Nov. 1988. Oregon Agricultural Experiment Station Technical Paper no. 7733. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.