الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
This work was aimed to study the f ac tors influencing
the severity of root rot disease of peanut and method of
control. The causal organisms were isolated from different
lOCalities in A.R.E., identified and the patnogenicity was
determined. The susceptability of different peanut varieties
to the disease was evaluated. The effect of organic and
inorganic manuring and ~hizobi~ inoculation on plant growth,
disease severity and nittogen fixation was determined. The
effect of different systemic and non-systemic fungicides on
growth of pathogens, plant growth, nitrogen fixation and
disease severity was investigated. Moreover, the effect of
these fungicides on the soil and rhizoshpere microflora Was
studied.
The results might be summarized as follows:
1. The fungi lihizoctonia sOlani (Kuhn), Sclerotium
rolfsii, Rhizoctoni.a bataticola (Taub.) Butl., F-usarium
0x’y’sporum(Sohlech tendahl) and .EgsaritynBolani (Martius)
were pathogenic to peanut causing root rot disease. li. solgni
was superior in this respect than §. rolfsii while the other
fungi were of low importance.
2. The local tested varieties were susceptible to
infeotion”with root rot disease organisms but Giza (3)
va.riety was less suceptible to infection as compar ed with
the other tested varieties.
3. Soil infestation with lie solan~ increased root rot
disease and decreased the numbers, dry weight, size of
nodules and total nitrogen content and dry weight of
plants.
4. Inoculation with Rhizobium c~re resulted in a
decrease in the percentage of disease peanut plants. It
increased the numbers, dry weight and size of nodules,
also dry weight of plants and total nitrogen content pet
plant. Organic manure gave the same results.
5. It Was found that nitrogen fertilization increased
the inQidence of disease, numbers, dry weight, size of
nodules, dry weight of plants and total nitrogen content ..
6. Soil infestation with g,. solani and .2• .t:0lfsii
alone or combined increased the percentage of pre-, postemergence
damping-off and root rot disease. However, it
decreased the nitrogen content. It also reduced the number,
fresh and dry weight of nodules and fresh and dry weight of
roots and shoots.
7. Inoculation with Rhizobiu-m.-. in soil infested with
the pathogens resulted in a decrease in the pre-, poatemergence
damping-off and root rot disease percentages.
While it increased the numbers, fresh and dry weight of
nodules. It also increased the fresh and dry weight of
plants and total nitrogen content.
8. Counts of total microbial flora in the soil were
lower than in the rhizosphere. Rhizosphere/Soil ratio (R/S
ratio) was high in the vegetative growth period. Fungicidal
treatment decreased the total microbial flora density.
9. Actinomycetes counts were low at the beginning of
the experiment but increased as the plant grew up. ActinomYcetes
counts in the soil were higher than those obtained
in the rhizosphere except in the case of the un-inoculated
soil treated with fungicides where higher count was observed.
R!S ratios for this grouP were negative and also quite law.
Fungicides differ~d in their effectiveness on actinomycetes
eouat.
10. The count of fungi was higher in the control than in
rhizosphere soil treated with fungicides especiallY in the
vegetative stage. At the flowering and maturity stages a
low count of fungi was observed.
11. The fungicides Bavistin and vitavaxlCaptan were the
most effective fungicideS in inhibiting the growth of lie
solani while vitavaxlCaptan and vitavaxlThiram were the most
effective in inh1biting tne growth of -S. .rolfeii. The other
fungicides inhibited the growth of the pathogens at varying
degrees.
12. Sclerotial formation of R-. -801-an-i waS completely
inhibited at low concentrations of Benlate and Brassicol.
Sclerotia of -S. -ro-lfsii were not formed at 5 ppm of Vitavax/
Captan and 10 ppm of Vitavax/Thiram.
13. Treating seeds with fungicides reduced the percentage
of pre- and post-emergence damping-off and root rot
disease in the field. The most effective fungicides were
found to be Benl.a te , Vitavax/Th1ram and Vitavax/Captant
respectively.
14. Tre ating soil with fungic ides reduced the percentages
of pre-, post-emergence damping-off and root rot
disease. Brassicol-75 and Orthocide-75 were the most
effective.