Efficacy of pyrimethanil in controlling green mouldof 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.