ROLE OF PRUNUS STEM PITTING IN THE DECLINE OF APRICOT TREES
Prunus stem pitting is a serious infectious disease that affects apricot and other stone fruits in Canada, the USA, and several European countries. Apricot trees affected by stem pitting show stunted terminal growth and chlorotic, drooping leaves that curl upward and lengthwise, often turning reddish in the fall. Leaf abscission occurs earlier than on comparable healthy trees. Fruit of affected trees may have an insipid flavor, they fall to size properly, ripen and drop prematurely. Affected trees may have very thick and spongy bark as compared to the bark of unaffected trees. Removal of the bark from the affected lower truck reveals pits and grooves on the woody cylinder. Wood pitting begins below ground, then gradually spreads into the roots and the trunk above ground. Considerable variation in the extent and severity of wood pitting is found between cultivars. Stem pitting is caused by certain strains of the tomato ring spot virus. The stem pitting agent can be readily graft- and soil- transmitted from apricot to other Prunus species and back to apricot. Naturally infected apricot, trees may show a slow decline, or they may develop rapid dieback of the terminal growth and die. The severity of symptoms and damage is determined by the cultivar and the strain of tomato ring spor virus. Control measures for prunus stem pitting should include: use of propagation material from healty trees and rogueing of pitted trees in nurseries and orchards. Repeated use of infested nursery sites for stone-fruit nurseries should be avoided.
Mircetich, S.M. (1981). ROLE OF PRUNUS STEM PITTING IN THE DECLINE OF APRICOT TREES. Acta Hortic. 85, 285-299