© Benaki Phytopathological Institute
Fusarium
and
Rhizoctonia
infecting native Greek tomato varieties
71
2003). Initial symptoms of Fusarium wilt are
described as vein clearing of the younger
leaves and leaf epinasty, followed by stunt-
ing, yellowing of the lower leaves, progres-
sive wilting of leaves and stem, defoliation
and finally plant death. In cross-sections of
the stem, a brown ring is evident in the area
of the vascular bundles (Bishop and Cooper,
1983; Di Pietro
et al.,
2003).
The soil-borne pathogen
Rhizoctonia
solani
Kühn [teleomorph:
Thanatephorus cu-
cumeris
(A.B. Frank) Donk] causes serious
damage to many economically important
horticultural crops (Baker, 1970; Anderson,
1982; Sneh
et al.,
1996). In the past few years,
the importance of the disease caused by this
pathogen has increased dramatically in Eu-
rope (Grosch
et al.,
2005).
R. solani
strains oc-
cur ubiquitously and are either saprophytic
or pathogenic to more than 500 plant spe-
cies. Damping-offdiseases causedby
R. solani
in greenhouse-grown vegetables are com-
monly encountered (Lumsden and Locke,
1989). Symptoms develop as dark brown to
black cankers on the base of the plant, which
increase in size over time resulting in plant
collapse (Baker, 1970; Agrios, 1997).
No information is available in the litera-
ture with respect to the reaction of the na-
tive Greek tomato varieties ‘Chondrokatsari
Messinias’ and ‘Katsari Santorinis’ to the in-
fection by soil-borne fungal pathogens or on
the effects of infection on plant growth and
development. The objectives of the pres-
ent study were to investigate
F. oxysporum
f.
sp.
lycopersici
and
R. solani
infection process
on the native tomato vars ‘Chondrokatsari
Messinias’ and ‘Katsari Santorinis’, record the
symptomatology of the diseases and corre-
late disease intensity (incidence and severi-
ty) with plant growth decline after infection.
Materials and Methods
Plant material, cultivation practices and
experimental design
Untreated tomato (
Lycopersicon escu-
lentum
L.) seeds of vars ‘Chondrokatsari
Messinias’ and ‘Katsari Santorinis’ obtained
from local growers were sown in 60 × 20 cm
plastic trays (INA plastics, Athens, Greece)
filled with sterile white peat moss (TS2 Klas-
mann-Deilmann, Geeste, Germany; pH 6.0).
Tomato seedlings were grown inside a non-
heated greenhouse located at the premis-
es of the Technological Educational Institute
of Peloponnese (lat. 37° 20΄ 20΄΄N, long. 22°
60΄ 51΄΄E) for 35 d and until they reached the
4-true-leaf stage (approx. 30 cm in height).
The young plants were then transplanted
individually into 5 lt plastic pots filled with a
mixture of white peat moss (TS2 Klasmann-
Deilmann, Geeste, Germany; pH 6.0) and
perlite (Perloflor, Isocon SA, Athens, Greece)
at 1:1 (v/v). The pots were then placed on alu-
minium benches (0.2 m width x 15 m length
x 0.5 m height) in a non-heated greenhouse
in a completely randomised design. Stan-
dard cultivation practices, such as plant tie-
up, irrigation and fertilization, were applied
to all plants. The nutrient solution used for
the fertilization of the plants consisted of (in
mmol/lt) 5.10 Ca
2+
, 2.40 Mg
2+,
, 7.00 K
+,
, 1.50
NH
4
+
, 3.60 SO
4
2
, 14.30 NO
3
-
, 1.50 H
2
PO
4
-
and
(in μmol/lt) 20 Fe 10 Mn, 5 Zn, 0.80 Cu, 35
B and 0.5 Mo. Electrical conductivity (EC)
and pH of the nutrient solution ranged be-
tween 2.4-2.5 mS/cm and 5.8-6.0, respec-
tively. Three hundred ml of the nutrient so-
lution was provided to the plants every two
days during the experimental period.
Two individual experiments, Experi-
ment 1 and Experiment 2, were conduct-
ed starting out at the end of February 2015
and finishing 95 d later. In Experiment 1, to-
mato plants of vars ‘Chondrokatsari Messini-
as’ and ‘Katsari Santorinis’ were challenged
with
F. oxysporum
f. sp.
lycopersici,
where-
as in Experiment 2, the same varieties were
challenged with
R. solani
. In each experi-
ment, six plants per variety and time of as-
sessment [i.e. 40 or 60 days post inoculation
(dpi)] were used as replicates.
Pathogen isolates, inoculum prepara-
tion and plant inoculation
For the inoculation of experimental
plants, strain BPIC2550 of
F. oxysporum
f. sp.
lycopersici
isolated from tomato plants (
Lyc-
