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POSTERS: Cultural control

Thermotherapy via aerated steam: a safe practice to strawberry with benefits in disease control
Nan-Yi Wang - Gulf Coast Research and Education Center, University of Florida. Natalia Peres- University of Florida - Gulf Coast Research and Education Center, William Turechek- USDA, ARS, U.S. Horticultural Research Laboratory

A thermotherapy protocol via aerated steam, including a 1 h treatment at 37°C, a 1 h cool-down, and a 4 h treatment at 44°C, has been confirmed to effectively reduce or eliminate pathogens from strawberry nursery stock. However, its practical adoption is hindered in part by the fear of potential harm to strawberry plants. In this study, we conducted field trials to evaluate the effect of the current thermotherapy protocol on plant quality in several strawberry cultivars: Florida Beauty, Florida Brilliance, Florida Radiance, Florida 127, Strawberry Festival, and Ventana. Within each cultivar, numbers of new leaves and runners on steam-treated plants were equivalent to those on nontreated controls. Similar results were observed for flowering onset, except that steam-treated 'Strawberry Festival' showed significantly earlier flowering than the nontreated control. Fruit yields of steam-treated 'Florida Beauty' and 'Strawberry Festival' were higher than their corresponding nontreated controls. Nearly all the strawberry plants, regardless of steam treatment, remained vigorous throughout the study, whereas 52% of nontreated 'Florida Radiance' collapsed, which was attributed to infection by Phytophthora spp. likely occurring in nurseries. Overall, our results indicated that thermotherapy via aerated steam is a safe practice for managing latent pathogens on strawberry nursery stock and can be integrated into the existing production practices to supply clean planting stock.