Management approaches of maize downy mildew using biocontrol agents and plant extracts
2009
Kamalakannan, A. | Shanmugam, V.
Downy mildew of maize caused by Peronosclerospora sorghi was significantly controlled by seed treatment and foliar sprays of a talc-based formulation of a Pseudomonas fluorescens strain under greenhouse and field conditions. Leaf extracts of Prosophis chilensis and Azadirachta indica were found to be equally effective as P. fluorescens in controlling maize downy mildew, although the extracts were not as effective at inhibiting conidial germination as the pseudomonad or as metalaxyl. These treatments also suppressed sporulation of P. sorghi on diseased foliage. Enhanced induction of defense enzymes, chitinase and β-1,3-glucanase appeared to be associated with control mechanism and metalaxyl did not show such induction. The reduction in disease incidence under field condition resulted in increased yield. The inhibitory effect of P. fluorescens and extracts of P. chilensis or A. indica make them potential alternatives to metalaxyl for control of maize downy mildew, although their efficacy, practical application and cost needs to be explored in greater detail before they can be incorporated into an integrated pest management programme.
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