Effect of Peach/Plum Graft Incompatibility on Seasonal Carbohydrate Changes1

Abstract

Abstract Spring-budded trees of peach/plum (Prunus persica Batsch. cv. Fay Elberta on the plum P. cerasifera Ehrh. × P. munsoniana Wight & Hedr. cv. Marianna 2624) showed foliar symptoms of incompatibility in early August, whereas a reciprocal combination, plum/peach, remained healthy. Within 2 weeks leaves and scion bark of the incompatible combination contained several times the concentration of starch found in comparable tissues of peach/peach trees. The level of polyols were similar in the peach scions of both combinations until end of summer. In the plum rootstock starch in the bark of the incompatible trees reached a maximum concentration at the beginning of August but was essentially depleted within the next 3 weeks, while the level of sorbitol decreased by half. In relation to compatible combinations, free sugars increased in the bark above the incompatible union and declined below. Presumably, failure of the phloem to function across the peach/plum union in mid-summer resulted in the markedly dissimilar carbohydrate levels in the graft components.