Efficacy of pyrimethanil in controlling green mould of postharvest citrus

The efficacy of pyrimethanil alone,pyrimethanil-imazalil or pyrimethanil-prochloraz mixtures were evaluated in controlling the green mould of postharvest citrus both under the conditions of laboratory and farmer's storage houses.In laboratory,aqueous fungicide solutions were applied by soaking citrus 12 to 18 h after inoculation.Pyrimethanil alone(at 500 or 1 000 mg/L),pyrimethanil-imazalil or pyrimethanil-prochloraz mixtures(at 500+500 mg/L)showed higher than 94% efficacy in controlling green mold regardless of the inoculation with imazalil-resistant or imazalil-sensitive isolates;whereas,imazalil alone(at 500 or 1 000 mg/L)was poorly effective in controlling imazalil-resistant isolate.In practical application experiments in three-farmer storages done in 2007 and 2008,pyrimethanil alone,pyrimethanil-imazalil or pyrimethanil-prochloraz mixtures at above concentrations performed higher efficacy than imazalil alone at same concentrations in the storage house where the imazalil-resistant isolate had been detected,but at similar controlling level in storage where the imazalil-resistant isolate had never been detected.In conclusion,pyrimethanil could be used to replace imazalil for controlling citrus green mould.It could be used as a single solution or mixtures of pyrimethanil-imazalil or pyrimethanil-prochloraz,at concentration of above 500 mg/L.