Chemical control of porina in South Otago sheep pastures

Abstract

Abstract Granular, emulsifiable concentrate and micro-encapsulated EC formulations of diazinon, fenitrothion, and chlorpyrifos, micro-encapsulated methyl parathion EC. and the growth regulator diflubenzuron were compared for control of porina (Wiseana spp.) in three trials in Otago. Porina mortality from fenitrothion EC applied at different times between February and June was compared to that obtained with diflubenzuron applied to pasture at different times between March and June and at a range of application rates. Fenitrothion EC. chlorpyrifos EC. and methyl parathion MEC caused the highest mortality of porina with fenitrothion EC applied in late May at a rate of 1.1 kg a.i./ha being the most cost-effective. However, chemical control of porina may not be economic at current prices for chemicals and pastoral products. Diflubenzuron did not appear to control porina effectively in these South Otago trials regardless of rate or time of application.