High Tunnels, Cultivars and Plant Types Influence Disease Incidence and Severity in Organically Managed Strawberries, Poster Board #101

Consumers desire organically produced strawberries, but concerns about disease and pest management prevent many berry growers from adopting organic practices. One common strawberry disease is Botrytis gray mold, which reduces marketable yields and decreases the shelf life of harvested fruit. Strawberry plants are also susceptible to Verticillium wilt, which reduces yields by causing plant collapse.  Plug plants of cultivars ‘Albion’, ‘Strawberry Festival’, ‘LCN’ and ‘Chandler’, and bare root plants of ‘Albion’ and ‘San Andreas’ were evaluated in high tunnel and open field locations in western Washington. The experiment was a split plot, with locations as main plots, and cultivars/plant types as subplots. The losses due to Botrytis in the tunnels were approximately 20% less than those in the open field (1.1% and 5.4%, respectively; P = 0.0042). The effect of cultivar/plant type on Botrytis incidence was highly significant (P < 0.0001): ‘Strawberry Festival’ and ‘Chandler’ had less Botrytis than ‘Albion’, ‘San Andreas’ and ‘LCN’. Plants grown under high tunnels had numerically, but not significantly, greater Verticillium incidence and area under the disease progress curve (AUDPC) values compared with those grown in the open field. ‘Albion’, ‘San Andreas’ and ‘Chandler’ had lower Verticillium incidence and severity than ‘LCN’ and ‘Strawberry Festival’ (P < 0.05). Bare root ‘Albion’ plants had lower Verticillium AUDPC values than those grown from plugs (P < 0.05).  Marketable yield was not influenced by production in high tunnels or the open field, but cultivar had a profound effect on yields. In high tunnels and in the open field, marketable yield of the dayneutral cultivars ‘Albion’ and ‘San Andreas’ was over three times that of the junebearing cultivars ‘Chandler’, ‘LCN’ and ‘Strawberry Festival’ (P > 0.05). This work confirms earlier results from this project, indicating that high tunnels can effectively reduce Botrytis, which is one of the major barriers to organic production. However, in the absence of crop rotation or other control measures, high tunnels may worsen Verticillium wilt. Cultivar choice is also critical to minimizing disease pressures, and to establishing productive plantings.