Abstract
Effects of partial soil sterilization for Tyrophagus similis Volgin were investigated. Soil sterilization treatments by solar heat, hot water, steam, and soil reduction were effective. Nevertheless, a few acarid mites survived in some cases in the greenhouses because of uneven heat treatment, or on the outskirts of greenhouses, and untreated areas. For that reason, we can not expect a lasting effect over a long period. It is not desirable that these soil sterilization methods be used in early summer. Short-term steam disinfection in spring or autumn will probably suppress acarid mite infestation. Use of this method will spread because of its economy and practicality if applied for prevention before mites' reproduction or as an emergency control measure after their outbreak.
