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Use
of active botanical extracts has been recognized to be one of the promising
components of integrated pest management strategies. With an objective
to test the efficacy of nettle extracts to suppress plant pathogenic Alterinaria
brassicae, the fungicidal bioassays were conducted at the Central Laboratory
of Institute of Agriculture and Animal Sciences (IAAS), Rampur in 2002-2003.
A total of 41 treatments including control (fungus grown in PDA ), a positive
check (fungus grown in carbendazim treated medium) and fungus grown in
39 types of nettle extract solutions were evaluated for the assessment
of fungicidal properties of the nettle extracts. Various extracts from
leaf, stem and roots of stinging nettle (Urtica dioca) were extracted
with methanol, ethylacetate, chloroform, hexane and distilled water. Pure
culture of Alterinaria pathogen was isolated and grown in the medium containing
the nettle extracts and their mycelial growth and spore germination behaviour
were evaluated. The in vitro experimental result showed that the extracts
presumably containing polar and intermediate compounds were able to inhibit
mycelial growth of the fungus up to 75%. These fractions may contain alkaloids,
coumarins, sterols and triterpenes. The extracts presumably containing
most polar, less polar and non-polar compounds such as polyoses, saponins,
tannis, lipids and ?-carotene were less effective to inhibit mycelial
growth of Alternaria brassicae. However, none of the extracts of nettle
were found effective in suppressing spore germination of the fungus. |
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