الفهرس 
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Abstract
SUMMARY
The present work was carried out to study the role of the biological
control of diseases caused by Rhizoctonla solani, Sclerotium rolfsii and
Corynebacterium flaccumfaciens in bean cultivars. These studies have been
done under laboratory, greenhouse and field conditions. Results obtained C8n
be summarized as follows:
1- Rbizoctonia solani, S. rolfsii and C.flaccumfaciens isolates varied in their
pathogenicity against different bean cultivars.
2- Different microorganisms used in these study as antagonists were isolated
from sclerotia of pathogenic fungi, rhizosphere of bean plants and lor
identified isolates obtained from Bacterial Dis. and Biological Control Dept.
Plant Pathology Inst. Agric. Res. Center, Giza, Egypt and Fungus and Plant
Pathology branch, Dept. Agric. Botany. Fac, of Agric. Moshtohor.
3- An aggressive isolates of R. solani and S. rotfsii were used under laboratory
conditions, to study the effect of physiological factors affecting antagonism
between pathogenic fungi isolates and different antagonistic fungi and
bacteria. Reaction in mycelial growth or sclerotial formation of S. rolfsii were
used as two parameter to measure the efficacy of the antagonist.
4- Data obtained under laboratory conditions show that, different antagonists
varied in their reaction according to different physiological factors. Glucose,
fructose and sucrose were the most favourable carbon source for the
antagonistic effect of against R. solani. Dextrin was the least one effecting the
antagonistic effect of fungi against R. solani. While, lactose, starch, dextrin
were the most favourable carbon source for the antagonistic effect against S.
rotfsii. Starch, sucrose, fructose and glucose were the most favourable carbon
source for antagonistic bacteria against R. solani . On the other hand, lactose,
glycerol and starch were the most effective carbon sources on the antagonism
between antagonistic bacterial isolates and S. rol[sii.
5- Ammonium tartrate and potassium nitrate were the most favourable nitrogen
sources for antagonism between different antagonistic fungi and R. solani and
S. rolfsii. On the other hand, urea and potassium nitrate were the most
favourable nitrogen sources for antagonism between different antagonistic
bacteria and R. solani. Sodium nitrate, ammonium nitrate and potassium
nitrate were the most favourable nitrogen sources for antagonistic effects of
different antagonistic bacterial isolates against S. rolfsii.
6- CIN ratios 15/2 and 25/5 were the most suitable ratios for antagonistic
effect of different antagonistic fungi and R. solani, whereas CIN ratio 00/2 and
25/2 were the most suitable ratios for antagonisms between different
antagonistic fungi and S. rolfsil. On the other hand, CIN ratios 1/0.5, 5/2.5 and
2/1 were the most suitable ratios for antagonistic effect of different
antagonistic bacterial isolates against mycelial growth of R. solani. While CIN
ratio 3/1.5 was the most suitable ratio for antagonism against S. rolfsii.
7_ Regarding the effect of pH value on the efficacy of different antagonists, it
was clear that, at pH 6.5 and 7 were the most suitable pH values for the
antagonistic effect between antagonistic fungi and pathogenic fungi (R. solani
and S. rolfsii ) causing increasing of reduction in mycelial growth and
reduction in sclerotia! formation of S. rolfsii. On the other hand, pH 6.6 and
7.6 were the most suitable pH value for the antagonistic effect of antagonistic
bacterial isolates and R. solani. While pH 6.6 and 7.0 were the most pH value
effects against mycelial growth of S. TolfsU.
C.- 8- Regarding the effect of temperature degrees on the antagonism, 25 and
300e were the most suitable degrees for antagonists effect against mycelial
growth of R. solani. While, 20 and 25°e were the most suitable degrees for
antagonisms between different antagonistic fungi and S. rolfsii. On the other
hand, 300e were more effective than 25°C on the antagonism between
different antagonistic bacterial isolates and R. solani or S. Tolfsii.
9- Morphological studied on the effect of antagonistic bacteria B. subtilis on
mycelium of R. solani. After 4 days showed that, mycelium of R. solani
showed malformed and lytic.
10- Histological studies, showed that, T. harzlanum parasitized sclerotia of S.
rolfsii and absolutely destroyed it within 10 days under laboratory conditions.
iI-Adding culture filtrates of different antagonistic fungi after 5, 10, 15 and 20
days to the medium of R. solani and S. Tolfsii led to reduction in mycelial
growth of the pathogenic fungi. Data obtained revealed that, positive
correlation between the percentage of reduction and rate of adding culture
filtrate and age of culture filtrates. Culture filtrates of T. hanianum iso.No.28
was the most toxic ones to R. solani mycelium while T. harzlanum iso. No.5
was the most effects against S. Tol/sii. On the other hand, slight differences
between T. harzianum iso.No 3, 4 and NO.5 on reduction in amount of
mycelial growth of R. solani. T. harzlanum iso.No.3 was the most toxic one
against S. rolfsii to reduction in amount of mycelial growth was filtrates taken
after 15 days of inocubation.
12- Effect of time inoculation, of the antagonists, on the mycelial growth of R.
solani and S. rolfsii or sclerotial formation of S. rolfsii were also tested. Data
obtained revealed that, positive correlation between inocubation period and
percentages of reduction in mycelial growth of R. solani and S. rolfsii or
sclerotial formation of S. rolfsii were recorded. All isolates of T. harzianum
showed more antagonistic effect than G.penicilloides on reduction in mycelial
growth and sclerotia! formation of S. rolfsii. On the other hand, Bacillus. iso.
No.2 and B. cereus were the most effect against R. solani, while B. subtilis
iso. No.2 and Ps. jluorscens were the most effects against S. Rolfsii.
13- Under greenhouse conditions inoculum potential of the aggressive
pathogenic fungi and methods of inoculation for the pathogenic bacterial
isolates indicated that, 6 g/kg of soil for R. solani and 75 sclerotia/kg of soil
for S. rolfsii were enough to destroy highest in % of bean plants. While
methods of inoculation of C.flaccumfaciens varied between different bean
cultivars.
14- Under greenhouse conditions, c.jlaccumfaciens as a causal organism
responsible for wilt disease in bean plants, was able to infect soybean, pea,
cowpea and water-melon. While broad bean, tennis, tomato, squash, rice and
lettuce were not susceptible to c.jlaccumfaciens.
15- Different antagonistic fungi were use as spore suspension or culture
filtrates to control disease incidence caused by R. solani and S. rolfsii in bean
compared with fungicide vitavax-captan 75% under greenhouse conditions.
Data obtained revealed that, spore suspension was more effective on control
disease incidence than culture filtrates or vitavax-captan and caused increase
in % survival plants, fresh, dry and No. ofpodsJpot. On the other hand, T.
harzianum iso.No.28 were more effective than other isolates.
16- Under the same conditions, seed or soil treated with antagonistic bacterial
isolates to control disease incidence caused by the same pathogenic fungi in
bean cvs. Data obtained revealed that, in regard to Giza 3 cv soil treated with
different antagonistic bacteria was more effective on reducing in % of disease
incidence than seed treatment which caused increase in % of survival plants.
While seed treated with vitavax-captan was more effective than bio-agents in
Contender and Bronco cvs. On the other hand, all biological agents were mere
effective on increasing No. of pods/pot than fungicide in all bean cvs.
Regarding fresh and dry weight/pot data indicate that, isolates of
antagonistic bacteria varied in their effects according to reaction between the
variety and the pathogens, and showed more or equal with chemical treatment
in increasing fresh and dry weight/pot for bean cvs.
17_ Regarding the effect date of application of biocontrol agents against
pathogenic fungi on disease incidence caused by R. solani and S. rolfsii in
bean cvs. under greenhouse conditions. Adding different antagonists before or
at sowing were more effective on reduction of disease incidence than any other
ways compared with fungicide treatment in case Giza3 and Contender cvs.
when used against R. solani.
Regarding No. of pods/pot B. subtilis was the most antagonists
effective in increasing No. of pods/pot when added to soil before sowing in
Giza 3 cv. While T. harzianum and Ps.fluorscens increased No. of pods/pot
when added at three times or at sowing respectively. Fresh and dry weight of
bean plants was clear when different antagonists were added at three times.
18- Regarding the effect of application time of adding antagonistic bacteriRl
isolates on % wilt disease incidence caused by isolates of C.flaccumfaciens
in bean cvs. Data obtained revealed that, adding different antagonistic bacterial
isolates at 72 hrs before inoculation of pathogenic isolates were more effective
on reducing in % wilt disease incidence in bean cvs. than adding at the same
time. On the other hand, Contender cv was the most affected by using
antagonistic bacterial isolates by only 9.2% wilt diseased. While Bronco and
Giza 3 cvs were slightly affected by them and 30.3 and 42.50/0wilt diseased
were obtained respectively. B. cereus was the most antagonists effective
against isolates of C flaccum/aciens and caused only 22.5 % wilt disease.
While no differences between B. subtilis iso.No.2 and Ps.Jluorscens in
controlling C. flaccum/aciens isolates in bean cvs. by caused 32.2 % wilt
diseased.
19- Comparison between the effect of different antagonists as seed dresser or
soil treatment on disease incidence caused by R. solani and S. rolfsii in bean
cvs. Data obtained revealed that, adding different antagonists as soil treatment
(granules on wheat straw) or as seed dresser were more effective than other
forms on disease incidence in Giza 3. On the other hand, T. harzianum and B.
subtilis were more effective than Ps:fluorscens. Seed treated with different
antagonists increased in No. of pods/pot in Giza 3 cv. than other ways.
Slightly differences between different treatments in increasing fresh and dry
weight/pot.
20- Under field conditions, the same three antagonists, T. harzianum, B.
subtilis and Ps. fluoTscens were used as seed or soil treatment and different
application dates for bean cvs during 1995 and 1996 seasons. Data obtained
revealed that, T. harzlanum and B. subtilis used as seed treating were the
most effective on reduction in disease incidence and increased yield of bean
cvs comparing with control or fungicide vitavax-captan.
21- Adding any of the tested antagonists two weeks before sowing seeds,
inhibited disease incidence and increased the yield of bean cvs., more
effectively if compared with adding at divided into two amounts or at two
weeks after sowing.
22- Under the same conditions, adding different antagonists at different forms
led to different degrees of protection against disease incidence in bean cvs.
Also, different antagonists behaved differently according to the variety of
treated plants. In general, using antagonistic fungi as granules ( on wheat straw
or bran) led to the most protection of disease incidence, and increased of yield
bean cvs. Regarding, the antagonistic bacteria, no trend was observed among
different forms in most cases for controlling of disease incidence and yield of
bean cvs during 1995 and 1996 seasons.