Occurrence and detection of lesser known viruses and phytoplasmas in stone fruit orchards in Poland

A survey was carried out on 38 commercial and experimental stone fruit orchards located in major growing areas of stone fruit trees in Poland to determine the incidence of lesser known viruses and phytoplasmas. Leaf samples from 145 sweet cherry and 102 sour cherry trees were tested for Little cherry virus 1 (LChV-1), Little cherry virus 2 (LChV-2), Cherry green ring mottle virus (CGRMV), Cherry mottle leaf virus (CMLV), and Cherry necrotic rusty mottle virus (CNRMV) using RT-PCR. Sixty samples collected from peach and 20 apricot trees were also tested for CGRMV. Eleven out of 145 sweet cherry and three out of 102 sour cherry trees were infected by LChV-1. CGRMV was detected in 10 sweet cherry, four sour cherry, 14 peach and two apricot trees. No LChV-2, CMLV and CNRMV were detected in any of the tested trees. Phloem tissue from samples of shoots collected from 145 sweet cherry, 102 sour cherry, 128 peach, 37 apricot, five nectarine and 20 European as well as Japanese plum trees were tested for phytoplasmas. The nested PCR of the extracted DNA with universal and specific primer pairs showed the presence of phytoplasmas in six sweet cherry, three sour cherry, nine peach, four apricot, one nectarine and three Japanese plum trees. The RFLP patterns of 16S rDNA fragments after digestion with RsaI, MseI, AluI, and SspI endonucleases indicated that selected stone fruit trees were infected by two distinct phytoplasmas belonging to the apple proliferation group. The stone fruit trees infected by LChV-1, CGRMV and phytoplasmas were grown in orchards localised in all seven regions