Page 15 - Volume 1, Issue 1, January 2008

New plant pathogens in Greece 13
Etoloakarnania) and PBCVd in quince (Cy-
donia oblonga Mill.) (Peloponnese) (Bou-
bourakas et al ., 2006b). In this study, the
wild species Crataegus was for the first time
reported as a host of PBCVd and PLMVd.
In 2000, Hop stunt viroid (HSVd, genus
Hostuviroid) was reported on apricot with
an incidence of 5% and although latent on
this host, it could potentially be transmit-
ted to other susceptible crops including
stone fruits (Amari et al., 2000).
Recently citrus mother trees of the col-
lection of the Agricultural Station of Poros
were found to be highly infected by Cit-
rus bent leaf viroid [CBLVd, formerly called
citrus viroid (CVd)-I, genus Apscaviroid]
and Citrus viroid III (CVd-III, genus Apscav-
iroid ). They were often found in mixed in-
fections with HSVd [formerly called cit-
rus viroid (CVd)-II], causal agent of citrus
cachexia disease and Citrus exocortis viroid
(CEVd, genus Pospiviroid), causal agent of
exocortis disease (Vidalakis et al., 2006).
The need to establish viroid-free mother
plantations through a national certifica-
tion program seems to be the best way to
combat these serious diseases.
3.2. Insect and mite transmitted viruses
3.2.1.Transmitted by aphids and mites
Apium virus Y  (ApVY, genus Potyvirus)
and Celery mosaic virus (CeMV, genus
Potyvirus)
During the years 2002-2004, a survey
was carried out to determine virus inci-
dence in celery ( Apium graveolens L.) and
parsley [Petroselinum crispum (Mill.) Ny-
man ex A.W. Hill] crops showing virus-
like symptoms, such as mosaic, yellow-
ing, stunting and leaf distortion. A total of
2094 celery samples and 221 parsley sam-
ples from various parts of Greece were ex-
amined (Houliara et al., 2006). In celery
crops, incidence of non-persistently trans-
mitted aphid-borne viruses CeMV and
ApVY was 60.6% and 8.1%, respectively.
Parsley samples also were found infected
by ApVY (64.3%) and CeMV (3.6%).
Beet western yellows virus 
(BWYV, genus Luteovirus)
BWYVisapersistentlytransmittedaphid-
borne virus producing yellowing symptoms
on a wide range of natural hosts including
vegetables, ornamentals and arable weeds.
In 2000, a survey in spinach (Spinacea ol-
eracea L.) crops revealed a high incidence
(18.7%) of the virus in Northern Greece, At-
tica and Evia (Dovas et al., 2001a). Moreo-
ver, the virus was also widespread in oth-
er cultivated plants such as chickpea (Cicer
arientinum L.), Sinapis alba L., broad bean
(Vicia faba L.) and in various annual and
perennial arable weeds (Flomis fruticosa,
Reseda alba, R. lutea and Malva sylvestris)
which consist important sources of virus
inoculum (Dovas et al., 2001e).
Citrus tristeza virus 
(CTV, genus Closterovirus)
Citrus tristeza virus causes the most de-
structive virus disease of Citrus spp. graft-
ed on sour orange rootstock and is one of
the most important quarantine pests in
the country. In 2000, the first CTV-infected
sweet orange cv. Lane Late tree grafted on
CTV-tolerant Carrizo citrange was found
in Argolis county, Peloponnese (Dimou et
al., 2002). This tree belonged to a batch of
CAC propagation material (20 trees) ille-
gally introduced from Spain in 1994. Erad-
ication measures were undertaken and
the disease was probably ruled out in Arg-
olis. However, in Crete, the second region
having accepted the same infected mate-
rial from Spain, the situation is more criti-
cal, since the virus has been identified not
only in the Chania region, where the ma-
terial was initially introduced, but also in
Rethymnon and Heraklion prefectures.
Over 4000 trees have been eradicated up
to now. The virus was recently detected
in orange trees of the Arta valley (North-
western Greece) (Barbarossa et al ., 2007)
and in Clemenpons trees in Skala Lako-