Suitability of Sweet Cherry ( Prunus AviumL.) Cultivars for Organic Production — Results of a Long Term Trial in Eastern Austria

Abstract

Although there has been a rising demand on the Austrian market in recent years, organic sweet cherry production has been limited particularly due to difficulty in controlling cherry fruit fly ( Rhagoletis cerasiL.). Only cultivars that ripen very early are not affected by this insect pest. Fruit rots caused by Moniliniaspp. are also difficult to control under organic production methods. This perennial trial aimed at defining the suitability of some old and new early-ripening cherry cultivars for organic production. In autumn 2003, eleven cultivars were planted in the Institute research orchard in eastern Austria. They had been grafted on the dwarfing rootstock Gisela5 and cultivated organically. Between 2006 and 2012, yield and growth characteristics, as well as susceptibility to plant diseases and pests (especially fruit damage caused by the cherry fruit fly), were evaluated.

Low (< 0.3% in the mean of four years) infestation with cherry fruit fly could be found on the very early (late May - early June) ripening cultivars 'Early Lory', 'Bigarreau Moreau', 'Bigarreau Burlat', 'Schachl', 'Marzer Kirsche' and 'Merton Premier'. Some later ripening cultivars, including 'Merchant', 'Bigarreau Burlat VG' and 'Valeska', which ripened in early June, were already infested by the larvae, but, in the most years at a level below the market tolerance of 2%, whereas the very late ripening control cultivar 'Sumtare' had about 20% of infested fruits.

Based on data gathered during seven years of evaluation, besides the very early ripening standard cultivar 'Bigarreau Burlat', which was not affected by fruit fly and showed good growth, yield and fruit quality characteristics and good fruit size (6.7 g per fruit), the cultivar 'Merchant', which matures about eight days after 'Burlat', and which had low susceptibility to leaf spots ( Blumeriella jaapiiR.), high specific cumulative yield (0.41 kg·cm ²) and good fruit size (7.1 g per fruit) would be suitable for organic production. With some restrictions, the very early ripening cultivar 'Bigarreau Moreau' (low specific cumulative yield of 0.17-0.22 kg·cm ^-2) could also be of interest to growers. None of the local cultivars can be recommended for commercial production because fruits were too small ('Langstielige' and 'Marzer Kirsche') or because of high susceptibility to mechanical fruit damage in years with rainfall during the harvest period ('Schachl').