Management of Cucumber (Cucumis sativus L.) Mildews through Azoxystrobin-Tolerant Pseudomonas fluorescens

The compatibility studies of Pseudomonas fluorescens (Pf1) with azoxystrobin at different concentrations viz., 100, 150, 200, 250 and 300 ppm revealed that it was compatible with all the concentrations of azoxystrobin tested and the growth of the bacterium was unaffected even at the maximum concentration of 300 ppm. The field experiment revealed a foliar application of Pf1 (2.5 kg ha-1) and azoxystrobin (250 ml ha-1) combined, reduced downy mildew as well as powdery mildew disease severities more than azoxystrobin (250 and 500 ml ha-1) alone. An application of Pf1+azoxystrobin treatment recorded only 2.22 and 1.00 Percent Disease Index (PDI) of downy mildew and 1.85 and 0.50 PDI of powdery mildew during the first and second seasons, respectively. The treatment also recorded a maximum fruit yield of 14.30 and 15.65 tonnes ha-1 for the first and second seasons, respectively. Application of Pf1 along with azoxystrobin significantly increased the survival of Pf1 in the phylloplane of cucumber crop. In addition, there was multifold increase in peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, ß-1, 3 glucanase, chitinase and phenolics in plants treated with Pf1+azoxystrobin.