Control of Phytonemus pallidus (Acari: Tarsonemidae) from strawberry transplants using controlled atmosphere temperature treatment

Since it inhabits young leaves and buds of strawberry (Fragaria x ananassa Duchesne) crowns, cyclamen mite (Phytonemus pallidus Banks) is a difficult pest to control with biological or chemical means once it is present in a field. Controlled atmosphere temperature treatment (CATT) is a successful technique that has been commercially used in the Netherlands for nearly 2 decades to disinfect strawberry nursery stock, including elimination of cyclamen mite. During CATT, plants are treated at 35 degrees C, 50% CO2, and 10% O-2 under high relative humidity for 48 h. The objective of this study was to test CATT against P. pallidus in North America at a scale that can be easily used on-farms by strawberry growers. Two greenhouse experiments were conducted where infested trayplants were treated with CATT or the acaricide abamectin, and P. pallidus number were compared to control plants. Plants were destructively sampled after 4 weeks, and CATT reduced mobile forms of P. pallidus by 99.9% in both experiments. Abamectin used in the first experiment had an efficacy of 95.5%. Our findings suggest that CATT is effective at nearly eliminating P. pallidus from strawberry planting material, and its application could reduce risks of field infestations and the need for multiple acaricide applications. While our results are encouraging, additional research is needed to assess the effects of CATT on strawberry plant survival, growth, and fruit production.