In a survey during [2006][2007][2008][2009] 947 field samples (bark, fruit and leaves) of cultivated and wild pome and stone fruit trees showing various symptoms, including scar skin, dappling, fruit malformation, leaf mottle and stem canker ( Fig. 1) were collected in different regions of Greece (Attica, Crete, Macedonia, Peloponnesus and Thessaly). Samples were tested for the presence of Apple scar skin viroid (ASSVd), Hop stunt viroid (HSVd) and Pear blister canker viroid (PBCVd), using tissue-print molecular hybridisation, reverse transcription-polymerase chain reaction (RT-PCR), cloning and sequencing.Tissue-print molecular hybridisation showed that approximately 400 trees were infected with only one viroid whereas 63 trees were co-infected by two or three viroids. RT-PCR confirmed mixed infections in 26 trees but the results were not clear for samples from the other trees. Fourteen trees in all, seven pear (Pyrus communis), three wild pear (Pyrus amygdaliformis), three apple (Malus domestica) and one quince (Cydonia oblonga) were infected with ASSVd and PBCVd; five sweet cherry trees (Prunus avium) were infected with ΑSSVd and HSVd, and seven trees, four apple and three wild apple (Malus sylvestris) were infected with ASSVd, PBCVd and HSVd. All three viroids were sequenced in two trees, ASSVd and PBCVd in a further six trees, and ASSVd and HSVd (partially) in a wild apple tree (Table 1) (Hassan et al., 2004; Tessitori et al., 2002) and of PBCVd, PLMVd and HSVd in pear (Fekih-Hassen et al., 2004) have been reported previously. The presence of natural viroid infections in wild species away from human influence in Greece suggests that ASSVd, PBCVd and PLMVd originated in wild hosts and are probably native to Greece (Kyriakopoulou et al., 2001); our data for ASSVd, PBCVd and HSVd support this hypothesis (Kaponi 2009).Mixed infections favour viroid recombination and evolution, and wild species used as rootstocks for cultivated species may serve as viroid reservoirs, making phytosanitary control critical (Randles, 2003).

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Veronica sibirica (Veronicastrum sibiriciim) is an erect perennial herb, an ornamental, and a traditional Chinese medicine plant distributed mostly in northeastern, northern, and northwestern China. It has dehumidifying and detoxifying properties, and is mainly used for the treatment of cold, sore throat, mumps, rheumatism, and insect bites (4). In June 2008 through 2012, leaf spots of V. sibirica were observed in the Medicinal Herb Garden of Jilin Agricultural University (43°48'N, 125°23'E) and the medicinal plantations of Antu County (43°6'N. 128°53'E), Jilin Province. Leaf spots were amphigenous, subcircular, angular-irregular, brown, and 1 to 10 mm in diameter; they occasionally merged into a larger spot with an indefinite margin or with a pale center and dark border. Pale conidiomata were hypophyllous and scattered on the spots. The conidiophores were 100 to 400 \xm high and clustered together to form synnemata 20 to 50 fjm in diameter, which splayed out apically and formed loose to dense capitula. Conidiophores occasionally emerged through the stomata individually and produced conidia on the surface of the infected leaves. The conidiogenous cell terminal was geniculate-sinuous with somewhat thickened and darkened conidial scars. Conidia were solitary or catenulate, ellipsoid-ovoid or subcylindric-fusiform, hyaline and spinulose, 4.01 to 7.18 X 11.16 to 20.62 |am with obtuse to somewhat attenuated ends, and slightly thickened, darkened hila. Six isolates were obtained from necrotic tissue of leaf spots and cultured on potato dextrose agar at 25°C. After incubation for 14 days, colony surfaces were white to pinkish. The colony diameter increased by 12 mm after 21 days' incubation. Hyphae were hyaline, septate, and branched. Conidiophores grew individually or fascicularly. The symptoms and morphological characteristics were consistent with previous descriptions (1,2), and the fungus was identified as Phacellium veronieae (Pass.) (U. Braun 1990). The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified using primers ITS4/ITS5 (3). The ITS was identical among all .six isolates (HE995799) and 98% identical to that of P. veronicae (JQ920427, HQ690097). Pathogenicity was confirmed by spraying five 1-year-old V. sibirica seedlings with a conidial suspension (10^ conidia/ml) of each isolate and five seedlings with sterile water as a control treatment. Plants were grown in the greenhouse at 20 to 25°C and were covered with plastic bags to maintain humidity on the foliage for 72 h. After 15 days, the same symptoms appeared on the leaves as described earlier for the field-grown plants; the control plants remained healthy. The same fungus was reisolated from the leaf spots of inoculated plants. Currently, the economic importance of this disease is limited, but it may become a more significant problem, as the cultivated area of V. sibirica is increasing. To our knowledge, although P. veronicae was recorded on the other species of Veronica {V. aiistriaca, V. chamaedrys, V. grandis, V. longifolia, V. p...

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