STUDIES ON SCLEROTIUM RQLFSII SACC. ON CROP PLANTS IN NORTHERN NIGERIA WITH SPECIAL EMPHASIS ON TOMATO
STUDIES ON SCLEROTIUM RQLFSII SACC. ON CROP PLANTS IN NORTHERN NIGERIA WITH SPECIAL EMPHASIS ON TOMATO
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Date
1984-02
Authors
WOKOCHA, ROLAND CHIMA
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Abstract
Field survey conducted over a period of five years
(1976 - 1981) in parts of northern Nigeria during this
study, indicate that crops such as tomato (Lycopersicon
esculentum), cabbage (Brassica oleraceae) and pumpkin
(Cugurbita moschata) were attacked in the field by
Sclerotium rolfsii, while others such as onion (Allium
cepa) bulbs and potato (Solanum tuberosum) tubers were
attacked in storage. Results of field surveys suggest
that tomato plant was frequently attacked by the pathogen
in the field.
Artificial inoculation in the greenhouse showed
that all 35 tomato cultivars evaluated were susceptible
to infection by S. rolfsii. Of the 40 different plant
species screened for susceptibility to infection by the
pathogen, only 'bahama' grass (Cynodon dactylon)
appeared to be resistant to infection by S. rolfsii.
Results of field surveys and artificial inoculations in
the greenhouse appear to have shown for the first time
in Nigeria that cabbage (B. oleraceae), spinach
(Amaranthus sp.), sorghum (Sorghum vulgare) and millet
(Penniseturn typhoides) are attacked by the basal stem
rot disease.
Results of in vitro screening of 26 fungicides
against S. rolfsii revealed that 13 of these fungicides,
notable the oxanthiin compound - Vitavax-, Du-Ter 50,
PCNB, Verdasan, Fernasan D and Cerosan practically
prevented any mycelial growth at active ingredient
concentrations as low as 5 to 50 p.p.m.
In vivo greenhouse tests showed that of the
fungicides which strongly inhibited the mycelial growth
of S. rolfsii on PDA, seven (Aatopam-N, captan, Dithane
M-45, Aldrex T, PCNB, Calixin M and captafol) appeared
to be non-phytotoxic to young tomato plants at the
concentrations inhibiting mycelial growth.
An evaluation of the various factors which influence
the development of the basal stem rot disease in the
greenhouse revealed that pre—inoculation mechanical
injury on tomato plants as well as low relative humidity
significantly enhanced disease severity. Trichoderma
viride completely prevented the appearance of the disease
when it was inoculated on tomato plants on the same day
as, or three days before inoculation with S. rolf sii,
but was ineffective when inoculated three days after
inoculation with the pathogen. PCNB was also found to
be efficacious in reducing the basal stem rot disease
when applied to soil 10 days before inoculation in the
greenhouse.
In field trials conducted in Samaru to evaluate
the efficacy of of some fungicides, antagonistic
micro-organisms and animal manures in reducing the
basal stem rot disease on tomato, PCNB and T. viride
were found to be highly effective in reducing the
disease.
Description
A THESIS SUBMITTED TO THE DEPARTMENT OF CROP PROTECTION,
FACULTY OF AGRICULTURE, AHMADU BELLO UNIVERSITY IN
PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE
OF DOCTOR OF PHILOSOPHY IN CROP PROTECTION.
February, 1984
Keywords
SCLEROTIUM,, CROP PLANTS,, NORTHERN NIGERIA,, SPECIAL EMPHASIS,, TOMATO