Systemic fungicides viz., azoxystrobin, tebuconazole, difenconazole, propiconazole, carbendazim, thiophanate methyl and azoxystrobin 11 % + tebuconazole 18.3% SC were evaluated at 0.1, 0.15 and 0.2 per cent concentration against Alternaria porri, which causes purple blotch of onion under in vitro condition. Among the fungicides, azoxystrobin 11 % +tebuconazole 18.3 % SC was found to be highly effective at 0.1, 0.15 and 0.2 per cent concentrations with the maximum per cent inhibition of 98 to 100. This was found to be significantly superior over all the other treatments. Field experiments were also carried out to know the efficacy of azoxystrobin 11% + tebuconazole 18.3% SC at 500, 750 and 1000 ml/ha against purple blotch of onion. This fungicide at 1000 ml/ha significantly reduced the disease with the PDI of 31.00 followed by the dose at 750 ml/ha (34.00 PDI) and recorded 21.91 and 21.31 t/ha yield, respectively as compared to the maximum PDI (81.00) and minimum yield (10.04 t/ha) in control.
A.S et al. (Fri,) studied this question.