Incidence of virus fungal diseases on three stone fruits cultivars in Hungary

Among stone fruit diseases, those fungal pathogens are of great importance which cause early leaf fall and fruit rot. Due to early leaf fall, nutrient accumulation stops from leaves to buds. Consequently, bud formation in summer is delayed and buds cannot develop fully by autumn as well as their susceptibility to frost injury increases during winter and next spring. Fungal pathogens causing early leaf fall include Polystigma rubrum on plum and Apiognomonia erytrostoma on apricot (Holb & Erdôs, 2005; Holb, 2005; Holb et al., 2007). Among fruit rot pathogens Monilinia spp. (mainlyM. fructigena and M. laxa) the most important stone fruit disease. Since the pathogens are wound parasites, it appears on the fruits at injuries after hail or strong pest damage. Brown rotting of fruits starts and then grey conidiophores appears on their surface. The fruits often mummify and stay on the tree. The primary inoculum sources of the disease are the dead woody parts and the fruit mummies. The disease can also cause significant damages during storage. Its host plants include the stone fruit species (Holb, 2004, 2006). Some studies evaluated susceptibility of stone fruit cultvars to fungal diseases which cause early leaf fall. On plum, study of Szabó (1997b) and Soltész (1998) showed that ’Ageni’, ’Althann ringló’, ’Silvia’, ’Ruth Gerstetter’, and ’Utility’ expressed no or little symptoms caused by P. rubrum. In this study, ’Debreceni Muskotály’ and ’Korai besztercei’ cultivars were highly susceptible to P. rubrum. In a Bulgarian study, ’Ahatan’, ’Sofia-2’, ’Gilej’, ’Strinava’ and ’Stanley’ cultivars were partially resistant, while ’Green gage’ and ’Cacanska najbolja’ cultivars were highly susceptible to P. rubrum (Borovinova, 2002). On apricot, Békési et al. (2000) demonstrated that cultivars ’Mammia’, ’Tomis’ and ’Nugget’ showed less severe symptoms of A. erytrostoma in the rainy years of 1999 than all other apricot cultivars. Study of Szabó (1997a) revealed that cultivars ’Magyar kajszi’ and ’Piroska’ were less susceptible to A. erytrostoma compared to commonly grown cultivars in Hungary. Szabó (1997a) classified several apricot cultivars into brown rot susceptibility groups. He evaluated cvs. ‘Budapest’ and ‘Mandulakajszi’ as highly, ‘Ceglédi óriás’, ‘Liget óriás’ and ‘Polonais’ as moderately and ‘Borsi-féle kései rózsa’, ‘Piroska’, ‘Pannónia’, ‘Ceglédi bíborkajszi’, ‘Magyar kajszi’ and ‘Rakovszky’ as lowly susceptible to blossom and twig blights caused by M. laxa. In the case of plum, fruit rot is the most important damage but flower infection can also occur. Such features as vulnerable fruit peeling, long, wet weather periods during fruit maturity and clustering of fruits, are the main factors responsible for susceptibility to brown rot infection (Soltész, 1997). Szabó (1997b) classified several European plum cultivars into brown rot susceptibility groups. He found that ‘Bluefre’, ‘President’ and ‘Stanley’ are highly, ‘Cacanska najbolja’ and ‘President’ are moderately, and ‘Besztercei’, ‘Silvia’ and ‘Tuleu gras’ are lowly susceptible to fruit rot caused by M. laxa. These pathogens are causing severe infections in Hungarian stone fruit orchards if the summer is rainy. The amount of precipitation was higher in summers of 2008 and 2009 which allowed detailed investigation on early leaf fall Incidence of virus fungal diseases on three stone fruits cultivars in Hungary