STUDIES ON Fusarium WILT IN SCENTED GERANIUM [Pelargonium graveolens (L.) Herit]
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Date
2020-12-30
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University of Agricultural Sciences, Bangalore
Abstract
Scented geranium is an important, perennial aromatic herb affected by several
diseases of which wilt caused by Fusarium oxysporum is becoming a major constraint in
production. Wilt symptoms such as yellowing, drooping of plants and vascular
discolouration were observed in the infected stems. Maximum wilt incidence recorded in
Tumakuru district (36.73 %). The wilt causing pathogen was isolated from infected plant
samples collected from different geranium growing areas of southern Karnataka and
pathogenicity was proved under greenhouse conditions. The re-isolated pathogen was
identified as F. oxysporum based on its morphological characters by comparing with
standard descriptions of Fusarium species and also confirmed the pathogen through
molecular characterization of isolates by using universal fungal ITS-1 and ITS-4 primers.
Sabouraud's dextrose agar (SDA) and corn meal agar (CMA) were found to be ideal for
radial mycelial growth and sporulation. The maximum growth and sporulation of the
pathogen was found at temperature 25 ˚C and pH of 6.5. Among the botanicals and bio
agents evaluated under in vitro condition against F. oxysporum, agave (59.31 %),
Trichoderma viride Tv- 8 (71.12 %), Bacillus pumilis (54.66 %) and B. velezensis Bv-P42
(53.61 %) were effective in inhibition of mycelial growth of the pathogen. Among the
fungicides evaluated, systemic fungicides carbendazim and propiconazole shower 100.00
per cent, combi products hexaconazole + captan 84.51 per cent and contact fungicide
copper oxychloride 56.48 per cent were effective as evidenced by maximum mycelial
growth inhibition compared to other fungicides under in vitro condition.