EARLY PERFORMANCE OF TWO EUROPEAN PLUM CULTIVARS ON THIRTEEN PLUM ROOTSTOCKS

The nursery and field performance of the rootstocks GF 655-2, Ishtara^® Ferciana, Jaspi^® Fereley, Julior^® Ferdor, Marianna GF 8.1, Myran^® Yumir, Myrobalan B, Myrobalan P 1254, Myrocal^® Fercino, Plumina^® Ferlenain, St Julien Hybrid No. 2 and Torniel^® Avifel and the standard rootstock ‘St. Julien Wangenheim’ were investigated during the years 2001–07. All rootstocks were budded with the plum cultivars ‘Kirke’, ‘Ive’ and ‘Opal’ and compared during the first six years after planting. The average bud take was 35%. The highest bud take for ‘Kirke’ was in combination with the rootstock ‘St. Julien Wangenheim’ with 75%. The highest bud take with ‘Ive’ was in the combination with Jaspi® Fereley with 52%. The combination of ‘Opal’ on the rootstock ‘St. Julien Hybrid No. 2’ had an 80% bud take. The most vigorous rootstocks were Myrocal® Fercino, Myrobalan P 1254 and Marianna GF 8.1, which on average increased the trunk diameter by 94.6, 93.6 and 84.9 mm, respectively, during the six years in the orchard. The rootstocks with the largest yield efficiency calculated as accumulated yield 2004–07 per cm2 trunk cross section area were GF 655-2 with the plum ‘Ive’ and Jaspi^® Fereley with the plum ‘Kirke’. Fruits of ‘Kirke’ on the rootstock Plumina^® Ferlenain matured and ripened 5 days earlier than any other rootstock combinations with ‘Kirke’ scions. The combination of ‘Kirke’ and the rootstock Jaspi^® Fereley each year resulted in a large crop and gave the largest accumulated yield at 25.6 kg/tree, in the years 2004–07. Four of the well producing rootstock combinations with ‘Kirke’ also produced the largest fruit. The significantly largest fruits came from the combination of ‘Kirke’ and Ishtara^® Ferciana at 50.4 g. The largest accumulated yield of ‘Ive’ was in combination with the rootstock GF 655-2 at 60.9 kg per tree. Of the thirteen rootstocks tested we conclude that none were truly dwarfing. The best growth control was provided by Ishtara® Ferciana and GF 655-2. Ishtara^® Ferciana contributed to the production of large fruits for both ‘Kirke’ and ‘Ive’. The most productive rootstocks were Jaspi^® Fereley with ‘Kirke’ and GF 655-2 with ‘Ive’.