Evaluation of different fungicides in the control of purple blotch [Alternaria porri (Ellis) Cif] of onion

Abstract

A field experiment was carried out to evaluate the effect of different fungicides on purple blotch [Alternaria porri (Ellis) Cif] of onion (Allium cepa L.) experimental farm during Rabi 2015-16 and 2016-17 in the Department of Plant Pathology, College of Agriculture, Swami Keshwanand Rajasthan Agricultural University, Bikaner. The experiment was laid-out in randomized block design with three replications during Rabi 2015-16 and 2016-17. The effective management of purple blotch of onion through application of different fungicides was appraised under field conditions. Among the nine treatments evaluated, the seed treatment with Tebuconazole @ 1g/kg + two spray Tebuconazole @ 0.1% was found significantly minimum per cent disease index of 17.75% and bulb yield 26.83 t/ha which was superior over other treatments and control. However, the result shows that the application of Tebuconazole was found superior and maximum inhibited the mycelial growth of Alternaria porri at 100 and 200 ppm concentrations and Azadirachta indica (Neem leaf extract) was found least effective at all concentrations against Alternaria porri. Moreover, the seed treatment with Difenoconazole @ 1g/kg + two spray of Difenoconazole @ 0.1% was recorded second best (PDI 29.03% and bulb yield 22.60 t/ha) but it was found statistically significant with the application of seed treatment with Tebuconazole + Trifloxystrobin @ 0.5g/kg + two spray Tebuconazole + Trifloxystrobin @ 0.05% (PDI 32.87% and Bulb yield 22.33 t/ha) followed by seed treatment with Propiconazole @ 1g/kg + two spray of Propiconazole @ 0.1% (PDI 33.83% and bulb yield 21.97 t/ha) in pooled analysis, respectively. The maximum PDI (74.00%) and minimum bulb yield (5.03 t/ha) was observed in control. Field observations of the different fungicides are very useful to effective control of purple blotch disease of onion as well as in-vitro technique for efficiently inhibit the mycelial growth of the test fungi.