SUITABILITY EVALUATION OF SEVERAL APPLE CULTIVARS FOR ORGANIC FRUIT PRODUCTION

摘要

Suitability of nine scab-resistant or partially scab-resistant apple cultivars: 'Bohemia', 'Rubinola', 'Topaz', 'Goldstar', 'Pinova', 'Redkroft', 'Free Redstar', Welfiree' and 'Gold Milenium' ('Early Freegold') for organic orchards was evaluated during the period 2002-2006. The experiment was set up in the spring of 2002 and consisted of two plots. In the first plot, no plant protection chemicals were applied either to the trees or to the soil. In the second plot, with limited spraying programme, only those compounds that are allowed to use in organic fruit production were applied in order to control pests and diseases: copper products three times; "Carpovirusine Super SC" and garlic extract "Liquid Bioczos" one time. Young shoots infested by apple mildew and aphids were cut back. After plantlng, the ground under tree rows was mulched with agricultural spun-web, linen residue felt or a sawdust in a 1.2 metre wide strip. Grass was allowed to grow between die rows and was regularly mown. During the years of the experiment, many trees were seriously infected by apple canker (Nectria sp.), what caused the loss of certain number of them. Trees planted in mulched soil with agricultural spun-web grew better and bore more fruit in comparison with the trees grown in linen residue felt and sawdust mulch. The highest yield was obtained from cultivars 'Gold Mileniurn', 'Pinova', Welfree' and 'Topaz'. The cultivars 'Topaz', 'Bohemia', 'Rubinola', 'RedkToft' and 'Gold Milenium' proved to be the most suitable for organic fruit production. The greatest problem was aphid control. Cutting back shoots with primary infestation was the most promising method.