Sum of 60 bacterial isolates were obtained from naturally infected
tomato collected from naturally infected tomato leaves and seeds in four
locations i.e. El-Doki (Super Marmand, cv), Qaha (Peto 86 cv and super
strain B cv), Fac. of Agriculture Ain Shams -Kalubia Governorate
(Money maker, Super Marmand and Super strain B cv) and Rashid
(Mors44, Niagra) Domiata Governorate. The isolated bacteria belong to 4
genera and 4 species.
2. Xanthomonas vesicatoria was the more occurred (30 trials of
frequency) in all tested samples comparing to the other isolated
bacteria. The highest isolation number and frequency% of X.
vesicatoria was recorded in Fac. of agriculture Ain Shams (63.6%)
followed by EL-Doki (50%) and Qaha location (35.7%), meanwhile,
the least frequency (29.4%) of X. vesicatoria was recorded in Rashid
location. Other bacteria were isolated and Rashid location showed the
highest number and frequency % (58.8%) followed by Fac. of
agriculture Ain Shams location (36.4%).Sixteen of cultivars and hybrids were used for the isolation of
pathogenic bacteria that caused spots on tomato plants. All tested
cultivars, Dora, Gs12, KTM 141, Niagra, Diamante F1, Hypride7796,
Super strain B hybrids, Mors44, VT916G.SI Hypride, HMX4791
Hypride and faqlta 38 gave negative reaction when direct planting on
the Nutrient agar (NA). Meanwhile, Super strain B was the only
resulted positive reaction for X. vesicatoria isolated. On the other
hand, all used seeds of cultivars and hybrids of tomato were showed
gave negative reaction for Pseudomonas isolation. Meanwhile, other
bacteria that isolated from tomato seeds of cvs and hybrids were
different according the cvs, hence seeds of Super strain B, Gs12 and
faqlta 38 were the only results for other bacteria isolated.
4. According the morphological, physiological and biochemical
characteristics, out of 60 bacterial isolates which isolated from
tomato seeds, leaves, stems and fruits, 30 isolates were identified as
Xanthomonas, 10 identified to each Bacillus and Pseudomonas.
Other lasted of 10 isolates were identified as non-pathogenic bacteria.
5. Regarding of pathogenicity test, 30 isolates of bacteria that
isolated from bacterial spot of tomato was tested for their ability to
infect of tomato and pepper plants. Twelve isolates of Xanthomonas
vesicatoria, numbers: Xv2, Xv3, Xv7, Xv8, Xv10, Xv13, Xv14, Xv20,
Xv22, Xv23, Xv26 and Xv28 were the highly pathogenic and caused
bacterial spot on tomato (leaves) and pepper (leaves), meanwhile,
eight isolates of X. vesicatoria (No. Xv1, Xv 4, Xv5, Xv9, Xv11, Xv12,
Xv15 and Xv24) were resulted the moderated pathogenic effect by
showing a few symptoms of leaves spot on tomato and pepper plants.
The last of the ten isolates of X. vesicatoria (No. X6, X16, X17, X18X19, X21, X25, X27, X29and X30) were non-pathogenic and no
symptoms was showed on tomato and pepper leaves after their tested.
6. Concerning the host range, three isolates of Xanthomonas
vesicatoria that caused bacterial spot of tomato, No. Xv28 was highly
pathogenic in Qaha, Xv22 which was highly pathogenic in Rashid and
Xv10 that highly pathogenic in El-Doki, were used to study of their
ability to infect of different hosts. Data indicated that, the three isolated
were highly pathogenic and caused bacterial spot on tomato plants,
meanwhile, the remained isolates were moderate pathogenic and
showed little symptoms on tomato leaves when tested for their
pathogenicity. All these tested isolates were highly pathogenic on
tomato and pepper and never affected potato and cabbage, common
bean, eggplant, lettuce, beans, strawberry and cantaloupe. On the
other hand, the three isolates showed moderately effect on datura
plants.
7. Different bactericides, antibiotics, oils and plant extracts,
inducing resistance, bio-agents were used at different concentrations
to study there effect on the growth of pathogenic bacteria
Xanthomonas vesicatoria isolates (as inhibition zone cm) under in
vitro conditions. As for the bactericides, Galbin-Cu48% and Copper
oxychloride 54% had inhibitory effect on growth of the pathogenic
bacteria compared with the control. Also, this inhibition was
increased according to the increase of concentrations of bactericides.
On the other hand, the different isolates of X. vesicatoria (Xv28, Xv22
and Xv10) were varied for their sensitivity to these bactericides. In this
respect, Copper oxychloride was more effective than Galbin-cu for
the reduction in growth of all isolates |
