STUDIES ON GRAY MOLD OF CASTOR CAUSED BY Amphobotrys ricini (N. F. Buchw.) Hennebert
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Date
2018-08-01
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University of Agricultural Sciences, Bangalore
Abstract
Castor crop suffers from many diseases of which gray mold is important.
Anamorphs of Botryotinia ricini viz., Amphobotrys ricini and Botrytis cinerea are found
to incite gray mold. On the basis of morphology of the fungus isolated from the castor
capsules collected at Gandhi Krishi Vignan Kendra, Bengaluru which was grown on oat
meal enriched medium produced septate and branched mycelium which was thin, hyaline
to light brown in colour and produced cylindrical, dichotomously branched conidiophores
bearing conidia and this was identified as Amphobotrys ricini. Morphological studies
revealed that highest radial growth was observed on Malt extract agar medium, but
profuse sporulation was in oat meal enriched medium. Maxium dry mycelial weight was
observed in Richard’s agar. Highest number of sclerotia were produced on Malt extract
agar whereas large sized sclerotia were produced on Richard’s agar and Malt extract agar.
The PCR amplification and sequencing of ITS rDNA region confirmed that A. ricini as
the cause of gray mold. Among the systemic fungicides Carbendazim, Propiconazole @
50, 250, 500 ppm showed complete inhibition; contact fungicide Mancozeb @ 1000 ppm;
combi fungicide Carbendazim + Mancozeb @ 250, 500, 1000 ppm; nano molecule
Silicon dioxide @ 250 ppm were found to be superior in inhibiting the growth.
Management of gray mold disease revealed that, least disease index with higher seed
yield was recorded in Carbendazim 1.0 g L-1 when prophylactic spray was given before
the onset of disease and next spray 15 days after first spray.