The effect of Salicylic Acid (SA) in inducing resistance in groundnut plants against Alternaria alternata was investigated. Foliar application of SA at the concentration of 1 mM significantly reduced the leaf blight disease intensity and increased the pod yield under glasshouse conditions. Changes in the activities of phenylalanine ammonium lyase, chitinase b-1,3 glucanase and in phenolic content on groundnut after application of SA and inoculation with A. alternate were studied. In SA-treated leaves (plants) an increase in phenolic content was observed five days after challenge inoculation with A. alternata in groundnut plants pretreated with SA. There was a marked increase in chitinase and pathogen inoculation in SA-treated leaves. In chitinase, b-1,3 glucanase activities were observed in response to plants with an increase in SA treated leaves. Foliar applications of SA-induced in peroxidase and polyphenol oxidase activities were observed upon challenge inoculation with pathogen.

No abstract

No abstract

Grapevine downy mildew is the most devastating disease throughout the world causing huge monetary losses. Twenty medicinal plant extracts and six phylloplane microfloras were evaluated for their efficacy against sporangial germination of grapevine downy mildew pathogen Plasmopara viticola in vitro. The results revealed that the Neem Seed Kernel Extract (NSKE) at 5% significantly inhibited the sporangial germination (75.36%) of P. viticola. Among the phylloplane microflora Pseudomonas fluorescens was highly effective in reducing the sporangial germination (64.26%). Post inoculation spraying of NSKE (5%) and P. fluorescens (0.2%) effectively inhibited the disease development in the greenhouse. Three sprays with NSKE (5%) and phylloplane P. fluorescens (0.2%): first spray after initial appearance of disease and the second and third at 10 day intervals were found to be promising in reducing disease incidence in the field.