SYMPTOMS OF DECLINE IN CANINO APRICOT IN ISRAEL
In the northern area with a high winter raifall /600 mm/ with 3 year old trees following symptoms were observed:
During the second summer in the first symptoms appear; tree shows suffering, as if from drought. Profuse gum exudates. Leaves turn yellow, premature drop. Fruit often shows black spots inside or outside. The following spring foliation is normal but during summer the symptoms reappear with increasing severity. This is often associated with necrotic spots in the xylem and necrotic strands in the cortex of trunk. Similar symptoms are found in the branches and often in the roots. Trees decline and die within 2–3 years.
In the southern, less rainy, but irrigated orchards /some are sparsely irrigated/ less severe symptoms appears. In severe cases sudden death of trees occurs at the early bearing stage with gumming from the trunk, branches and near buds. Leaves are shed and the trees die usually after fruit has set and developed. This may also happen with progressively more gumming during 2–3 years associated with a dieback of terminal growth.
In other cases deep fissures appear on the back along the trunk and lower part of main branches. These are much deeper than ordinary fissures in the apricot back. Virus is suspected and on one occasion successive trees in a row were found to be affected. We do not know yet whether these trees, fruiting normally, will decline prematurely, but it may possibly be associated with a shorter life span, at least in some cases.