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Laboratory
and field experiments were conducted to investigate effectiveness of nettle
(Urtica dioica L.) extracts for management of alternaria blight of radish
incited by Alternaria spp. at Rampur, Nepal, during 2001/2002. Effectiveness
tests for inhibition of spore germination and mycelial growth were carried
out in laboratory on glass slide and poisoned media, respectively. Field
experiment was conducted in a split-plot design with spray frequencies
as main-plot and various concentrations of fresh and fermented nettle
extracts and Dithane M-45 as sub-plot factors. Dithane M-45 appeared to
be superior to all other treatments in suppressing conidia germination
and mycelial growth in laboratory and disease in field. Among nettle extracts,
in general, fresh nettle sap extracted in urine appeared the best, followed
by fresh nettle extract in water and fermented nettle extract in vitro
as well as in field. Fresh nettle extract in urine, diluted to 5% in water,
showed second highest suppression of conidia germination and fungal growth
after Mancozeb in vitro. In general, 20% fresh nettle sap extracted in
urine suppressed the disease highest in field and produced the highest
yield among nettle extracts. Fresh nettle sap extracted in cattle urine
seems to be a potential measure for the management of alternaria blight
of radish. |
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