In the July 2002 issue of NF Ag News and Views, I reported on the results of a strawberry yield trial conducted during the 2001-2002 growing season using the annual plasticulture production system. This system employs the use of raised beds covered with black plastic mulch and equipped with drip irrigation. The highest yielding variety in this trial was "Chandler" producing an average yield per plant of 0.57 lbs. with "Jemstar" a close second at 0.52 lbs. Jemstar produced the largest berry at 0.6 oz. per berry, large enough to impress the most demanding strawberry junkie.
Berry size, however, is only one part of the equation – yield per plant is just as important. Unfortunately, yields obtained in the 2001-2002 trial were only a third to a half of what is being obtained in other parts of the country under favorable growing conditions.
While plastic-mulched raised beds reduce the risk associated with flooding, they do not protect against freezing temperatures, strong winds and hail. Fruit and foliage exposed to rainfall are susceptible to disease, which, if not treated, can further reduce yield and quality.
At the Noble Foundation, hoop houses have been demonstrated effective in protecting many high-value crops from weather extremes, thereby improving yield and quality. Hoop houses also have a proven track record of accelerating plant growth, thereby decreasing the time to mature a crop.
Beginning October 2002 and lasting through May 2003, a study was conducted at the Noble Foundation Horticulture Center in our 23-foot by 68-foot triple side-vent hoop house to evaluate the performance of five commercial strawberry varieties: Chandler, "Camarosa," "Sweet Charlie," "Treasure," "Gaviota" and one experimental line, "JP4," grown in a hoop house environment. The variety Jemstar was not included due to a lack of availability.
On Oct. 1, three rows of transplants (produced from tip cuttings obtained from Canada) were set into each of four beds. Rows were spaced 12 inches apart with individual plants in each row spaced 16 inches apart. Each variety (treatment) was replicated four times with each of the four beds serving as a replication. Each treatment contained 80 plants, 20 per replication. The hoop house remained fully vented October through February to limit the amount of premature fruiting. Beginning March 1, the vents were adjusted as needed to maintain a target daytime temperature of 80 degrees F.
Harvest began on April 4 and ended May 23. Results for marketable weight and berry size are reported in Table 1.
Treasure was the top yielding cultivar (1.55 lbs./plant) with Chandler coming in a close second (1.40 lbs./plant). Camarosa, one of the most utilized varieties in the world, performed relatively poorly (0.94 lbs./plant). All of the varieties, however, exceeded the yield obtained by Chandler in our 2001-02 plasticulture variety trial.
Berry size of the JP4, Treasure and Camarosa exceeded the reported weight of Jemstar (0.6 oz.) in the 2001-02 study. Berry size for Chandler, Gaviota and Sweet Charlie were all acceptable based on industry standards.
Initial results suggest that both yield and berry quality are bolstered by the hoop house environment. Additional trials will need to be conducted to verify these results. Because weather conditions vary from year to year, this study will need to be conducted for a minimum of three years. In addition, an economic analysis will need to be performed before any recommendation can be made.
If early results are any indication, hoop houses just might be the ticket for taking strawberry production to the next level in the southern Great Plains.