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 (760) and Py.701-202 (701), both apparently of Pyrus communis L. origin - as interstock grafts to confer psylla resistance to the commercially important 'Spadona Estiva' (Pyrus communis) scion (Spadona) cultivar. The interaction of the interstocks with quince (Cydonia oblong Mill.) and Pyrus betulifolia Bunge rootstocks was also tested. RESULTS: Usage of Py.760-261 (760) and Py.701-202 (701) as interstocks for the psylla-sensitive Spadona resulted in a five-fold decrease in the C. bidens population, apparently as a consequence of 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 '701' interstock equaled or even exceeded those of the control in fruit quantity, fruit size and soluble solids content, especially on P. betulifolia rootstock. CONCLUSION: 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. (C) 2017 Society of Chemical Industry