Improving Crop Load on the Plum Cultivar ‘Kirke’ by Utilization of New Rootstocks

Abstract

The plum cultivar "Kirke" was budded on 13 selected rootstocks including the standard rootstock St. Julien A and evaluated under field conditions during 2001-08. The average bud take was 43%, with the highest bud take on St. Julien A at 75%. No take was observed with Marianna GF 8.1 and only 15% take in combination with Myrobalan P 1254, all of which died during the first year in the nursery. The most vigorous rootstock was Myrocal® Fercino with an increase in the trunk diameter (TD) of 94.6 mm during the first 6 years in the orchard. GF 655-2 had the largest dwarfing effect with a TD of 48.8 mm. Although none of the tested rootstocks were found to be truly dwarfing, the best growth control was provided by Ishtara®, Ferciana and GF 655-2. Ishtara also produced the largest fruits, at 50.4 g, and a high yield. The most productive rootstock was Jaspi® Fereley with an accumulated yield at 25.6 kg per tree. Fruits on the rootstock Plumina® Ferlenain matured 4-5 days earlier than from any other rootstock combinations.