Strawberry Production with Protected Culture in Southern California

Total and marketable yield, fruit size and fruit rot were evaluated for 'Camarosa' and 'Ventana' strawberry cultivars grown with or without protected culture in southern California in 2003 and 2004. In both years, bare-root transplants were established on October 5 using standard "open field" production methods. Fifty-five days after transplanting, metal posts and arcs were positioned over portions of the field and covered with 0.0324 m-thick clear polyethylene tarp to create "tunnel" structures 4.9 m wide, 25 m long, and 3.5 m high. Each tunnel covered three contiguous strawberry beds, and experimental design was a randomized complete block with four replications, with individual plots consisting of 20 plants. In 2003, early season (January-April 1) marketable yields in tunnels were 90% and 84% greater than outdoor culture for Ventana and Camarosa, respectively. In 2004, use of tunnels resulted in a 140% marketable yield increase for Ventana and 62% for Camarosa (January-March 31), however unusually high temperatures (38 degrees C) in April resulted in reduced yields in tunnels thereafter. In both years, increased early production coincided with highest fresh market fruit prices, resulting in $ 14,000-18,500 ha(-1) greater returns compared to open field production. For both cultivars, tunnel production resulted in 45-76% fewer non-marketable fruit due to less rain damage, better fruit shape, and decreased incidence of Botrytis cinerea. For all treatments, fruit size decreased as season progressed and this effect was more pronounced in tunnels after April. Overall, these studies indicate that tunnels have considerable potential for enhancing early-season production and profitability of strawberries in southern California.