Peculiarities of naturalization of bacterial fire blight of fruit crops in Ukraine.
First occurrence of fire blight caused by Erwinia amylovora in Ukraine was recorded in 1997 on pear and apple trees at the time of intensive growth. Disease resistance was found only in pear cv. Kirgizskaya zimnyaya among the 50 cultivars studied. Among the apple cultivars, resistance was found in Melba, Slava Pobeditelyam and Boskopskaya krasavitsa, which were disease free. Monitoring fruit orchards in different regions of Ukraine during 1997-2007 showed that temperature and RH unfavourable to disease development reduced disease spread alongside with the resistance factor.