First Report on Phytoplasmas Infecting Wild Apples and Wild Pears in Croatia

Wild apple (Malus sylvestris L. Mill.) and wild pear (Pyrus pyraster L. Burgsd.) are direct ancestors of modern apple (M. domestica Borkh.) and pear (P. communis L.) cultivars grown and utilized for human consumption. In late summer of 2012 and 2013, leaves of 140 wild pear and 61 wild apple trees from 10 locations across Croatia were collected and tested for presence of phytoplasma DNA. Disease symptoms (yellowing leaves) were observed on nine apple and five pear trees sampled. Our findings confirm the presence of phytoplasmas belonging to these three groups (SrI, SrIII, and SrX) in new hosts-wild apples and pears. The results imply that these phytoplasmas might infect a number of yet unknown hosts that either do not show any symptoms or show weak, uncharacteristic symptoms. Furthermore, they might pose a threat to commercially grown pears and apples.