الفهرس 
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Abstract
Root-rot, wilt diseases are the most important diseases of many crops (cotton, legumes
and fruit trees). Biological control plays an important role in suppression of soil borne plant
pathogens (root-rot and wilt disease)Instead of chemical substances. For this, the present work
was aimed to select the best organisms, which are good antagonists; studying ecological
considerations associated with natural biocontrol; modes of action of biological control agents;
separation and identification of antibiotics for the bioagent and mode of use of the antagonist.
The obtained results can be summarized as follows:
Eighty one fungal isolates belonging to 23 genera namely: Absidia, Acremonium,
Alternaria, Aspergillus, Chrysonilia, Cladosporium, Cunninghamella, Eurotium, Fusarium,
Fusoma, Geotichum, Montospora, Moniliella, Mucor, Mycogone, Nematoctonus, Penicillium,
Blastomyces, Trichoderma, Rhizopus, Scopulariopsis, Streptothrix and Verticillium were isolated
from the rhizosphere of examined plants at Kafr Elshiekh.
Forty two fungal isolates belonging to 14 genera namely: Alternaria, Aspergillus,
Chrysonilia, Cladosporium, Eurotium, Curvularia, Fusarium, Penicillium, Rhizoctonia,
Rhizopus, Scopulariopsis, Streptothrix, Trichoderma and Verticillum were obtained from the
rhizosphere of the examined plants at Baltim province.
The causal organisms of root-rot and wilt diseases of cotton plants from Kafr Elshiekh
localities were isolated. Twenty six fungal isolates belonging to 9 genera namely: Acremonium,
Alternaria, Blastomyces, Fusarium, Fusoma, Mycogone, Rhizoctoniasolani, Scopulariopsis and
Verticillium were isolated from the rhizosphere of the different plants collected from Kafr
Elshiekh localities.
Also fourteen dangerous agents belonging to 5 genera were isolated from wilted plants in
the cultivated areasof Baltim localities these isolates are: Alternaria, Fusarium, Rhizoctonia,
Scopulariopsis and Verticillum.
Virulent and avirulent organisms were tested against each other in-vitro to select the most
active organism as a biocontrol agent. Data showed varying degrees of antagonism against the
fungal pathogens. About 20 fungal species out of 55 isolates were the most promising i.e.
Trichoderma harzianum (Vf), T. harzianum (Ta), T. harzianum (Sb), Cladosporium
macrocarpum (Ta), C. resinea (Ta), Absidia corymbifera (Ta), Absidia corymbifera (Vf), C.
cladosporioides (Vf), Aspergillus niger (Vf), Aspergillus niger (Td*), Aspergillus niger (Vf*),
Aspergillus niger (Sb), Chrysonilia sitophila (L), Chrysonilia sitophila (Ta), Chrysonilia
sitophila (Vf), Aspergillus niger (Ta), M. altissima (Vf), Aspergillus penicillioides (Vf),
Penicillium echinulatum (L), Aspergillus flavus (C) (from Kafr Elshiekh localities).
While about about 12 isolates “from Baltim localities” out of 28 isolates were promising
i.e. Trichoderma harzianum (Sb), T. harzianum (Sb*), T. harzianum (Vf), T. harzianum (Ta), T.
harzianum (C), Penicillium paraphergal (C*), Aspergillus flavus (Ta), C. sphaerospernum (Vf),
A. niger (Ta), A.niger (Vf), A. niger ( C ) and T. Verdi (Sb).
To avoid the common problem of the introduced antagonist failing to establish and
survive in the rhizosphere, the most potent 9 fungal antagonistic strains were selected perfectly
to be tested against each other.the selected fungal antagonists were tested for their ability to
antagonist each other. Data revealed the presence of variable antagonistic effects between the
different antagonistic fungi. Aspergillus niger (Ta)K, T. harzianum 64(Vf)B, T. harzianum
64(Ta)B, T. harzianium 42(Vf)K, T. harzianum 42(Sb)K, T. harzianum 64(C)B, C.
macrocarpum 15(Ta)K, Cunninghamella mart 17(Vf)K and T. harzianum 64(Sb) B. Data also
indicated that Trichoderma harzianum isolated from Vicia faba roots from Kafr Elsheikh locality
was the most powerful biological agent. It showed broad spectrum and high stability against the
tested organisms. In the second place T. harzianium (Vf) isolated from Baltim it also showed
high activity. Aspergillus niger isolated from Triticum durum from Kafr Elsheikh was less active
but it showed clear and stable zone.
In-vivo studies,to determine the effect of biocontrol agents on the pathogens, revealed
that Trichoderma harzianum 42(Vf) was more efficient as biocontrol agent in reducing dampingoff
and wilt diseases incidence in cotton plants. It was selected for the preceding experiments.
Antibiotics were extracted from Trichoderma harzianum 42(Vf) culture filtrate with
ethylacetate.
The ethyl acetate extract of culture filtrate of Trichoderma harzianum was subjected to
Gas chromatography / Mass spectroscopy ( GC / MS ). Fifty three compounds were identified
and classified into (2 acetlenic, one furanoid and 11 benzenoid products ) 1- 14 ), hydrocarbons
(15–29), volatile alcohols ( 30 – 37 ) , fatty acid esters ( 38 – 49) and phthalic acid products (50 –
53 ). Many compounds were reported as antifungal and antibacterial.