Off-Season Greenhouse Strawberry Production

Strawberry production in the mid-South is mostly done in the field with harvest from April to June.  There is year-round demand for fruit with the highest prices from November through February. Our research is ongoing to evaluate off-season strawberry production in polyethylene-covered greenhouses. Runner tips from ‘Camarosa’, ‘Carmine’, ‘Ventana’, ‘Albion’ and ‘Strawberry Festival’ were established as plug plants 1, 15, or 31 of July 2007.  In mid September, the plug plants were transferred to 15.2 cm x 11.4 cm round pots containing 50% Promix and 50% perlite. An experiment was established with eight replications of five cultivars, three plug dates and six plants per experimental unit in a randomized block design. The plants were fertigated with timing controlled by a solar collector/controller (Davis Engineering, Los Angles, CA). Bumblebees were used to pollinate the flowers. Yields of the five cultivars were relatively low for the fall (before 1 January) because of cultural factors, but those propagated on 1 July had approximately 4% and 75% more fruit than those propagated 15 July or 31 July, respectively.  ‘Carmine’ produced high quality fruit and yielded the most fruit during November and December. ‘Ventana’ yielded the most fruit for the entire harvest period (600 g/plant) and had very good quality. However, this cultivar had relatively low fall yields unless propagated by 1 July. ‘Carmine’ and ‘Camarosa’ yielded about 20% and 10%, respectively, of their fruit in the fall but produced similar amounts (520 and 535 g/plant, respectively) for the entire harvest period.  ‘Albion’ and ‘Strawberry Festival’ were relatively productive in the fall; producing 18% to 21% of their total yield, but were less productive than other cultivars after 1 January. The twospotted spider mite was initially the most difficult pest to control, but high populations of Phytoseiulus persimilis provided adequate control. Minor outbreaks of whiteflies were controlled with Encarsia formosa. Amblyseius cucumeris reduced a high thrip population in January but did not adequately control the pest.