Steam Treatment Controls Cyclamen Mite ( <i>Phytonemus pallidus</i> ) Without Compromising Strawberry Plant Survival, Growth and Yield

Cyclamen mite is a pest of strawberry that is difficult to control due to its small size and preference for inhabiting concealed spaces in new plant growth. Steam treatment of transplants effectively reduces some strawberry pathogens and may be a valuable tool against cyclamen mite. Strawberry transplants (“Jewel” and “Annapolis”) that were artificially infested with cyclamen mite were steam-treated at 44°C for 1 h or at 48°C for 0.5 h. Both treatments reduced cyclamen mite numbers by > 99% compared to the control, and 44°C for 1 h had no negative effects on plant survival, growth or yield. In a second, similar, field experiment, transplants (“Jewel”) were categorized by crown size as small (6–8 mm) and large (10–13 mm) and steam-treated at 44°C for 1 or 4 h. Steam treatments reduced cyclamen mite numbers by 92–93% compared to the control, but in the 4 h treatment, survival of small crowns was 40%. Steam treatment of strawberry transplants at 44°C for 1 h is an effective tool and may reduce reliance on miticides for cyclamen mite control. Additional research is needed to determine the optimal steam treatment protocols for cyclamen mite control and to understand the effect of the steam treatment on strawberry transplants with different crown sizes.