Autumn acaricide applications as a new strategy to control the pear leaf blister mite Eriophyes pyri

The pear leaf blister mite Eriophyes pyri (Pagenstecher) causes severe damage to pear leaves and fruits. As mites are well sheltered from exposure to plant protection agents during summer and acaricide efficacy is reduced when temperatures are low in early spring, autumn acaricide applications were evaluated to control mites as they migrate to their hibernation sites. Post-harvest sulphur and mineral oil treatments were applied in September 2003 and mites were monitored in the following spring. Only the sulphur-treated trees were virtually free of blisters. Sulphur treatments showed an efficacy of 95.3% (one application) to 99.6% (three applications), whereas, mineral oil treatments only had an efficacy of 12.8% (one application) to 69.6% (three applications). That post-harvest sulphur applications could decontaminate heavily infested orchards was possible was confirmed by a large-plot trial in two orchards in 2004/2005.