S16 - Session P2 - Determining Rootstock Incompatibility for Patterson Apricot

Authors: Kari Arnold *, Roger Duncan, Maher Al Rwahnih, Daniel Green, Jacqueline Vasquez-Mendoza, Leslie Alfonso, Cole Margarite

Little is known regarding rootstock incompatibility in apricots. With the growing development of rootstocks for almonds, apricot growers are tempted to use almond, plum, apricot and peach hybrid rootstocks for apricot orchards. Unfortunately, not all rootstocks may be compatible. We tested the Stanislaus County, CA commonly grown Patterson variety of apricot on nine rootstocks with varying backgrounds. Certified, grafted trees were provided by cooperating nurseries, planted at the Stanislaus Agricultural Center in Modesto, CA, in January of 2019 and June of 2019, unstaked and grown according to industry practices. In 2020, we found two of the nine varieties were incompatible based on loss of tree via breakage at the graft union.