Grafting on resistant interstocks reduces scion susceptibility to pear psylla, Cacopsylla bidens

BACKGROUND Pear psylla is a major obstacle to efficient integrated pest management in pear orchards in Israel and around the world. We used two accessions with natural resistance to pear psylla Cacopsylla bidens (Sulc) – Py.760-261 and Py.701-202 – as interstock grafts to confer psylla resistance to the commercially important ‘Spadona Estiva’ scion (Spadona) cultivar. The interaction of the interstocks with quince and Pyrus betulifolia Bunge rootstocks was also tested. RESULTS Py.760-261 and Py.701-202 interstocks on the psylla-sensitive Spadona, resulted in a C. bidens population decreased of five-fold, apparently due to antibiosis affecting nymph survival. Additionally, psylla survival was negatively correlated with the interstock length and amount of foliage. The yield and fruit quality of Spadona grafted on the Py.701-202 interstock equaled or even exceeded the control in fruit quantity, fruit size and soluble solids content, especially on P. betulifolia rootstock. CONCLUSIONS Susceptibility to pear psylla decreased significantly following grafting of commercial Spadona on resistant interstock. This is the first demonstration of increased resistance to pear psylla conferred by the use of resistant interstock in pear trees and among the few examples demonstrating transfer of resistance to insects from the interstock in fruit trees.