REACTIONS OF KOREAN NEW CULTIVAR 'HAEGEUM' AGAINST MAJOR DISEASES OF KIWIFRUIT

Abstract

‘Hayward’ (Actinidia deliciosa [A. Chev] Liang et Ferguson), which has been cultivated since the late 1970s, is the most popular green kiwifruit cultivar in Korea. However, ‘Hayward’ has been known to be susceptible to problematic foliar diseases such as bacterial canker, bacterial leaf spot, powdery mildew and fungal leaf spot diseases on kiwifruit trees grown at open-field orchards during growing season and postharvest fruit rot diseases during storage and distribution of harvested fruits. ‘Haegeum’ (A. chinensis Planchon), which is one of the new yellow kiwifruit cultivars bred in recent years, has been released at growers’ orchards since 2007 in Korea. Responses of ‘Haegeum’ against the major diseases of kiwifruit were compared with those of ‘Hayward’. The disease severities of the foliar diseases of ‘Hayward’ and ‘Haegeum’ were investigated at six naturally infected orchards during the growing season in 2013. The incidence rates of the postharvest fruit rot diseases on the fruits harvested in 2012 were also investigated at two naturally infected orchards. The disease severities of bacterial canker and bacterial leaf spot diseases were 18.5 and 63.5% on ‘Hayward’ at an orchard, but the disease severity of bacterial canker was 1.2% and no bacterial leaf spot was observed on ‘Haegeum’, respectively. Furthermore the disease severities of powdery mildew ranged from 9.4 to 84.8% on ‘Hayward’ at four orchards, while those on ‘Haegeum’ were less than 20%. The disease severities of leaf spot diseases induced by several fungi were 27.4 and 5.0% on ‘Hayward’ and ‘Haegeum’, respectively. The incidence rates of postharvest fruit rot diseases were 18.5% on ‘Hayward’ and 3.3% on ‘Haegeum’. The overall results reveal that ‘Haegeum’ is relatively resistant to the major diseases of kiwifruit compared with ‘Hayward’.