Susceptibility of Austrian apricot and peach cultivars to

1548 stone fruit trees (1435 trees of P. armeniaca, 113 trees of P. persica) were examined by PCR for ESFY to get information on spread and susceptibility of cultivars and rootstocks used in Austrian stone fruit production. Cultivar susceptibility seems to be less important for tolerance to ESFY than rootstock resistance. Apricot cultivars on rootstocks of myrobalan, commonly used in Austria, are more infected than cultivars on plum rootstocks. Data on peach and apricot rootstocks are not representative as both are not commonly used in Austrian apricot production. In addition, the presence of peroxidase activity in shoot sieve tubes of infected apricot trees (Hungarian Best) reveals that peroxidase is involved in defense mechanisms in plant-pathogen interaction.