Page 16 - Volume 1, Issue 1, January 2008

K. Elena et al. 14
nias (Southern Peloponnese) imported
from Spain five years ago (Dimou, person-
al communication), so that special actions
have to be taken in these regions too.
CTV is transmitted semi persistently
by aphids and Aphis gossypii (Glover), al-
though not very efficient, is considered
as the most important vector in Greece.
The arrival of Τoxoptera citricida (Kirkaldy),
the most efficient vector of CTV, in 2003 in
Europe (Portugal and Spain) renders the
whole situation even more critical, impos-
ing the establishment of rigorous quaran-
tine and phytosanitary measures.
Cucumber aphid borne yellows virus 
(CABYV, genus Polerovirus)
CABYV is responsible for yellowing
symptoms, in cucurbits especially in open
fields grown melon (Cucumis melo L.) and
cucumber (C. sativus L.), causing serious crop
losses. This virus is phloem restricted, aphid
transmitted in a persistent manner, was first
world characterized in France in 1992 and
was first reported in Greece the same year
(Katis et al., 1992). In 2000, a survey in cu-
curbit crops showed that its incidence in
zucchini (Cucurbita pepo L.), in melon and
cucumber crops was 40%, 20% and 20% re-
spectively (Papavassiliou et al., 2006).
Onion yellow dwarf virus  (OYDV, genus
Potyvirus), Leek yellow stripe virus (LYSV
genus Potyvirus), Garlic common latent
virus (GCLV, genus Carlavirus), Shallot
latent virus (SLV, genus Carlavirus), Garlic
virus B (GarV-B, genus Allexivirus), Garlic
virus C (GarV-C, genus Allexivirus), Garlic
virus D (GarV-D, genus Allexivirus)
A large scale survey conducted a few
years ago on garlic (A. sativum L.), leek (A.
porrum L.), onion (A. cepa L.) crops and wild
Allium species in Greece revealed serious
virological problems, especially on garlic,
as a result of Greek growers’ practice to
produce their own garlic propagation ma-
terial (Dovas et al., 2001b). The potyviruses,
OYDV and LYSV, which are transmitted by
aphids in a non persistent manner, are the
most important viruses of garlic, resulting
in high yield reduction. These viruses were
found to be the most abundant and wide-
spread in Greece (up to 100%).
Significant differences were found re-
garding the frequency and the distri-
bution of the garlic carlaviruses, which
are also transmitted non-persistently by
aphids, but cause only latent infections.
GCLV was restricted to Southern Greece
(in Arcadia 97.6%) and SLV was only de-
tected in low incidence in areas, where
propagation material was imported from
China and Iran. Since aphids transmit car-
laviruses less effectively than potyviruses,
it seems that carlaviruses are mainly trans-
mitted by vegetative propagation
Allexiviruses are mite transmitted and
induce mild or no symptoms in Allium spp.
GarV-B, GarV-CandGarV-Dwere foundonly
in garlic and their regional distribution was
irregular. Their incidence was very high (up
to 100%) in three out of five regions. The
spread of allexiviruses takes place primarily
during bulb storage, where their eriophyid
mite vector Aceria tulipae (Keifer) can eas-
ily spread, and rather scarcely in the field.
When farmers use their own propagative
material as it happens in Greece, 100% to-
tal crop infection is most likely to occur.
The incidence of virus-like symptoms
in leek crops ranged from 10% to 90% in
different regions and fields and all symp-
tomatic plants were found to be infect-
ed by LYSV. All-year-around cultivation of
leek is a common practice and it seems to
be the main reason for the high incidence
of the virus in the country.
Virus incidence in onion was low and
OYDV was the only virus found in few sam-
ples from Southern Greece. A. ampelo-
prasum L. spp. ampeloprasum (L.) Breistr.
and A. Flavum L., were the only wild Allium
species found to be infected with LYSV.
The poor phytosanitary condition main-
ly of garlic crop, as shown above, can be
only overcome through the use of virus-free