Page 12 - Volume 1, Issue 1, January 2008

K. Elena et al. 10
vars, which were grouped to highly resistant,
partially resistant and susceptible ones (Sa-
hin and Miller, 1997; Carisse et al., 2000).
Besides lettuce, other natural hosts
of the pathogen are orchids, ornamental
plants (Syngonium sp.), asparagus lettuce
and wild lettuce (Bradbury, 1986). Symp-
toms were also produced by the patho-
gen on tomato and pepper after artificial
inoculation (Sahin and Miller, 1998).
The pathogen is transmitted with con-
taminated seed (Sahin and Miller, 1997; Ca-
risse et al., 2000). The primary sources of
inoculum include the infected plant debris
in the field and the contaminated seeds
for long distance transmission. It is inter-
esting for the epidemiology of the disease
that the pathogen was found to survive on
leaves of weeds (Barak et al ., 2001).
Measures of integrated control (use of
healthy seed or seed heat treated in hot
water at 50°C/20 min, destroy infected
plant debris, use drip irrigation, crop ro-
tation, resistant varieties, sprays with cop-
per compounds) are recommended to
eliminate the pathogen and the disease.
Xanthomonas cynarae  Trebaol, Gardan,
Manceau, Tanguy, Tirily, Boury
The pathogen was found for the first
time in Greece, to infect artichoke (Cynara
scolymus L.) cultivations in the prefecture
of Heraklion, Crete (Goumas et al., 2002).
The symptoms of the disease were wa-
tersoaked spots on the bract leaves of the
artichoke heads. The spots gradually co-
alesced to form larger brown necrotic ar-
eas. No symptoms were observed on oth-
er parts of the plants. Among varieties cv.
Lardati was more susceptible.
The detection of the pathogen in in-
fected artichokes was easily performed
by direct isolation and identification using
morphological, biochemical tests and the
polymerase chain reaction (PCR).
As a result of the infection of the bracts
the quality and the market value of the har-
vested artichoke heads are depreciated.
Integrated control measures (destroy
infected heads, avoid overhead irrigation,
sprays with copper compounds) are rec-
ommended to diminish the infection.
2.1. Concluding remarks
The five plant pathogenic bacteria re-
ported for the first time inGreece, since 1990,
are responsible for serious diseases and con-
siderable economic losses, in many coun-
tries. However, they do not currently seem
to constitute a serious threat in Greece, since
there are not reports of considerable dam-
ages and wide spreading of the pathogens
in the country yet. It is possible that the inte-
grated control measures recommended af-
ter the first detection-identification of the
pathogens, were applied successfully to a
great extend. An assessment of the cultivar
resistance to the pathogens will be useful in
future crop rotation schemes.
3. Plant viruses and viroids
The last twenty years research on plant vi-
ruses has been extensively carried out by
Table 2. New plant pathogenic bacteria in Greece, 1990-2007.
No Name of the pathogen Host plant Reference
1. Pantoea ananas watermelon Goumas & Hatzaki, 1998
2. Pseudomonas syringae pv. apii celery Goumas & Lalla, 2004
3. Pseudomonas syringae pv. porri leek Glynos & Alivizatos, 2006
4. Xanthomonas campestris pv. vitians lettuce Alivizatos & Glynos, 1992
5. Xanthomonas cynarae artichoke Goumas et al., 2002