EFFECT OF APPLE CHLOROTIC LEAF SPOT VIRUS ON YIELD AND QUALITY OF FRUITS FROM 'GOLDEN DELICIOUS' AND 'SAMPION' APPLE TREES

Apple chlorotic leaf spot virus (ACLSV), the type species of the genus Trichovirus, is one of the most widely distributed plant viruses infecting pome and stone fruits. The effect of ACLSV on the yield and fruit quality of ‘Sampion’ and ‘Golden Delicious’ cultivars grafted on M.9 rootstocks were studied. Quality parameters (weight, percentage of blush, russeting, total soluble solids, titratable acidity and flesh firmness), internal ethylene concentration in the core of fruits and starch index were measured in the fruits. Mean yield of fruits from virus free trees (control) of both cultivars grown on M.9 rootstock was higher then from infected trees. The weights of fruits from the control ‘Sampion’ and ‘Golden Delicious’ trees were higher than the weight of fruits from infected ones. Fruits from virus free ‘Sampion’ trees were more coloured then fruits from the infected trees. ‘Golden Delicious’ apples from virus free trees were less russeting than infected trees. Quality of fruits depended on the cultivars, growing season and health status of the tree as well.