EVALUATION OF PLANT EXTRACTS FOR THE CONTROL OF SEEDLING BACTERIAL BLIGHT OF COTTON INDUCED BY Xanthomonas campestris pv. malvacearum (Smith) Dye
EVALUATION OF PLANT EXTRACTS FOR THE CONTROL OF SEEDLING BACTERIAL BLIGHT OF COTTON INDUCED BY Xanthomonas campestris pv. malvacearum (Smith) Dye
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Date
2002-04
Authors
Shenge, Kennenth Chivir
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Abstract
Aqueous extracts of six plants, namely Garlic {Allium sativum L), Custard apple Annona
senegalensis L), Borreria verticillata L., Jatropha curcas L, the Sweet basil (Ocimum
basilicum L), and Neem (Azadirachta indica (A.), Juss) were evaluated for the control of
bacterial blight of cotton. Streptomycin and three preprietory chemicals; bronocot (12%
broropol), Apron plus (10% metalaxyl, 6% carboxin, and 34% Furathiocarb) and Apron star
(20% Thiamethoxam, 20% Metalyaxyl-M, and 2% Difenoconazole) served as checks
alongside an untreated control. Assessments of the extracts was done in vitro, in the
glasshouse, and in the field to determine the efficacy of the extracts against the disease.
Two methods were used to evaluate the plant extracts in vitro, namely, dilution plate count
and agar cup methods. Garlic (A. sativum) was found to be most effective, and significantly
reduced bacterial population and growth over the untreated control. A. senegalensis, B.
verticillata, and J. curcas were moderately effective, while the performance of 0. basilicum
and A. indica relative to untreated control was very marginal. In the glasshouse
experiment, the extracts were evaluated for their effect on seed-seedling parameters.
Germination, stand establishment, shoot length root length, stem diameter and vigour of
seedlings arising from seeds treated with the various plant extracts were assessed.
Treatments were found to have no effect on germination stand establishment and root
length. Extracts of A. sativum were found to be phytotoxic at high concentrations, as
evidenced by the significantly reduced shoot length and plant vigour. However specific
experiments to investigate this observed phytotoxicity did not confirm this observation.
Plant extracts were also evaluated under field conditions for their effect on germination,
stand establishment and seedling bacterial blight. In these experiments, extracts of garlic
produced rates of germination which were marginally higher than those of all the other
plant extracts. All the plant extracts significantly reduced the incidence of seedling
bacterial blight although they had no effect on severity of the disease. However, extracts of
garlic were significantly more effective in reducing the incidence seedling bacterial blight
over the untreated control; and was indeed on the same level of effectiveness with
bronocot.
Description
A thesis submitted to the Post-Graduate School, Ahmadu Bello University, in partial fulfillment
of the requirements for the Degree of Master of Science in Crop Protection.
Department of Crop Protection
Faculty of Agriculture
Ahmadu Bello University, Zaria
Nigeria
APRIL, 2002
Keywords
EVALUATION,, PLANT,, EXTRACTS,, CONTROL,, SEEDLING,, BACTERIAL,, BLIGHT,, COTTON,, INDUCED,, Xanthomonas campestris pv, malvacearum (Smith) Dye.