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Strawberry annual plasticulture shows promise in Oklahoma
Several varieties evaluated in recent Noble Foundation/OSU study

ARDMORE, Okla. — Treating strawberry plants as annuals — planted, harvested and destroyed within a 12-month period — provides the benefits of uniform plant stands unaffected by summer disease, drought or weed competition, as well as earlier fruit harvest, larger berry size, the potential for heavier yields, and shorter turnaround time from planting through harvest (eight months). Initially used by growers on the West Coast and later refined at North Carolina State University, this method is known as the annual plasticulture system.

Noble Foundation horticulturist Steve Upson and Oklahoma State University research and Extension horticulturist Dr. Lynn Brandenberger recently completed a study of strawberry annual plasticulture at the Foundation’s Horticulture Center.

"The study evaluated the performance of several commercial strawberry varieties using the annual plasticulture system," Upson said. "Another objective of the study was to determine if strawberry transplants produced in Oklahoma could compete with Arkansas-grown transplants in terms of yield and fruit quality."

Six varieties  — Chandler, Gaviota, Jemstar, Camarosa, Sweet Charlie and Festival — were selected either based on current industry use as a plasticulture variety or potential for use in this system. Treatments consisted of Oklahoma- and Arkansas-grown transplants of each variety with the exception of Festival, which could not be obtained from the Arkansas nursery.

The site for the study consisted of 22 40-inch by 30-foot permanent beds on 5-foot centers. The beds were equipped with drip irrigation and covered with black plastic mulch. On Oct. 1, 2001, transplants were set in beds. Harvest began on April 22 and ended on May 17.

All of the Arkansas-produced Jemstar and most of the Gaviota transplants died shortly after transplanting. Death loss of the Oklahoma-produced transplants was insignificant. Oklahoma-grown transplants out-yielded Arkansas-grown transplants regardless of variety.

To be fair, the researchers said, the Arkansas-grown transplants were in poor condition when they were received. According to Brandenberger, the plants had been treated for a fungal infection at the nursery but still appeared to be sick.

"Considering the condition of the Arkansas-grown transplants, the yield differences are not surprising," Upson said. "These results suggest that only the best quality disease-free transplants should be used in the plasticulture system."

Considering results from Oklahoma-grown plants only, Chandler ranked first in marketable yield while Gaviota ranked last.

For many years, Chandler was the strawberry variety of choice among plasticulture growers on both the East and West coasts. Recently, Camarosa has replaced Chandler as the preferred variety based on its equivalent yield potential, superior fruit characteristics and greater resistance to anthracnose, a fungal disease common to strawberry. In the Foundation study, however, Camarosa yielded only two-thirds of what Chandler did.

Even more surprising was the performance of Jemstar. It ranked second in marketable yield (just behind Chandler) but first in average fruit weight. Just as impressive was Jemstar’s ability to produce consistently large berries throughout harvest. The berry size of Jemstar was 0.64 ounces per fruit, and in a taste test conducted at the Foundation, Jemstar ranked first in both berry appearance and flavor.

The results of this study should not be considered conclusive, Upson cautioned. Growing conditions and pest populations change from year to year, and additional trials will need to be conducted over several years before either the Foundation or OSU can recommend any variety with a high degree of certainty, he said.

"Despite the many questions yet to be answered, one thing is certain — the future of annual strawberry plasticulture in Oklahoma appears to be 'berry, berry' good," Upson said.

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Photo Cutline: Jemstar berries at their finest

The Samuel Roberts Noble Foundation, headquartered in Ardmore, Okla., is a non-profit organization conducting agricultural, forage biotechnological, and plant biology research; providing grants to numerous non-profit charitable, educational and health organizations; and assisting farmers and ranchers through educational and consultative agricultural programs.

To learn more, visit the Noble Foundation Web site at http://www.noble.org.

More news releases available at www.noble.org/Press_Release