Disease incidence on different cultivars of apple tree for organic growing

Abstract

The incidence of diseases in fourteen apple cultivars and three hybrids planted in an orchard and managed under an organic system were examined in Lithuania in 2007-2008. Infection by leaf blotch (Phyllosticta spp.), apple scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha), bark diseases and physiological damage to fruit were evaluated. During experimental years apple trees cv. 'Aldas' were the most damaged by leaf blotch, the disease incidence and intensity was 42% and 13%, respectively. Cultivars ‘Florina’, ‘Enterprise ® ’, 'Roksana', 'Rajka' and hybrid No 20490 were damaged less than 10% by leaf blotch. The most damaged (39-55%) by scab on leaves were cvs. 'Pilot' and 'Pinova' apple trees; meanwhile, the fruits were slightly damaged. Powdery mildew was observed only in cv. 'Lodel', the incidence was 23%. Physiological damage was observed mostly on cvs. 'Goldstar' and 'Aldas' fruits. No bark diseases were observed on any apple tree cultivars and hybrids.