EFFICACY OF COLLOIDAL SILVER PARTICLES AGAINST SELECTED PLANT PATHOGENS
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Date
2016-12-29
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Studies on efficacy of colloidal silver particles against late blight of potato and
bacterial blight of pomegranate were carried out during 2014-16. Colloidal silver was
synthesized by the ‘bottom up’ approach of wet chemical synthesis and analyzed by laser
Dynamic Light Scattering (DLS). The particle size was in the range between 11.17 to
5186 nm with a mean diameter of 149.4 mm, of which 93.60 per cent particles measured
171.8 nm in diameter. The colloidal silver @ 500 ppm concentration was recorded (86.13
%) significantly maximum inhibition of Phytophthora infestans mycelia growth whereas
@ 10 and 25 ppm completely inhibited Xanthomonas axonopodis pv. punicae. The
physical incompatibility was noticed when colloidal silver combined with fungicides
Cymoxanil 8 % + Mancozeb 64 % WP and Dimethomorph 50 % WP due to change in
the pH (8) of mixed solution, but physical compatibility was observed when colloidal
silver particles antibiotic Streptocycline (Streptomycin sulphate 90 % + Tetracycline
hydrochloride 10 %). The pH of the mixed solution was acidic (5.6). Phytotoxicity was
recorded at 750 ppm of colloidal silver alone and in combinations with fungicides and
antibiotic on both potato and pomegranate. In field studies, 500 ppm of colloidal silver in
combination with 0.2 per cent of Cymoxanil 8 % + Mancozeb 64 % recorded maximum
reduction of late blight severity as compared to either colloidal silver alone and its
combination with Dimethomorph 50 % WP @ 0.20 per cent. No significant enhancement
of inhibitory activity was observed when applied with antibiotic Streptocycline against
pomegranate bacterial blight. The increased activity of defense enzymes viz., PO, PPO,
PAL, chitinase, total phenols and higher accumulation of chlorophyll was observed in
late blight infected potato and pomegranate plants upon treatment with either colloidal
silver alone or in combination with fungicides/antibiotics.
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