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Management of late leaf spot of groundnut ( Arachis hypogaea ) with chlorothalonil‐tolerant isolates of Pseudomonas aeruginosa
Author(s) -
Krishna Kishore G.,
Pande S.,
Podile A. R.
Publication year - 2005
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/j.1365-3059.2005.01160.x
Subject(s) - chlorothalonil , biology , grape seed extract , horticulture , fungicide , pseudomonas aeruginosa , microbiology and biotechnology , food science , bacteria , medicine , genetics , alternative medicine , pathology
Fifteen groundnut‐associated bacterial isolates that inhibited by > 90% the in vitro conidial germination of Phaeoisariopsis personata , causal agent of late leaf spot disease of groundnut, were applied as a prophylactic spray (10 8 cfu mL −1 ) and tested for control of the disease in the glasshouse. Two groundnut seed‐associated bacterial isolates, GSE 18 and GSE 19, identified as Pseudomonas aeruginosa , reduced the lesion frequency (LF) by up to 70%. A 90‐day‐old peat‐based formulation of P. aeruginosa GSE 18 reduced LF measured 15 days postinoculation by up to 60%. Both P. aeruginosa GSE 18 and GSE 19 were tolerant to chlorothalonil (Kavach®) up to 2000 µ g mL −1 in LB broth. In glasshouse trials, GSE 18 and GSE 19 tested in combination with reduced concentrations of chlorothalonil were highly efficient in management of the disease. The disease was completely controlled by chlorothalonil (> 250 µ g mL −1 ), and in the presence of GSE 18 or GSE 19, 100 µ g mL −1 chlorothalonil was equally effective. Application of rifamycin‐resistant mutants of GSE 18 or GSE 19 together with chlorothalonil significantly increased the survival of these isolates in the groundnut phylloplane. In the field, a combination of GSE 18 and 500 µ g mL −1 chlorothalonil reduced disease severity comparable to 2000 µ g mL −1 chlorothalonil alone. Use of chlorothalonil‐tolerant pseudomonads together with a quarter concentration of the recommended field dose of chlorothalonil doubled pod yield compared with the untreated unsprayed control.