STATESBORO, GA—Growers in southeastern Georgia have the perfect combination of climate and soil to produce some of the world's best onions: the famous Vidalia sweet onions. Prized for their mild taste and sweetness, Vidalia onions are shipped throughout North America for use in recipes and relishes.
Onion producers in the Vidalia region have traditionally used transplants to produce dry bulb onions. Transplants are grown on farms in high-density plantings, then pulled and transplanted to their final spacing. The delicate nature of Vidalia onions requires that they be transplanted and harvested by hand. In fact, the entire Vidalia onion crop of 12,000 to 14,000 acres is hand-transplanted over an 8- to 9-week period.
This practice of hand transplanting relies heavily on a migrant labor force and is significantly more expensive than machine transplanting. Although field workers have historically been available during the onion season, producers in the area are concerned about the possibility of a dwindling labor force in the future.
George E. Boyhan, an Extension Horticulturist at the University of Georgia's Southeast Georgia Extension Center, and colleagues Juan Carlos Diaz-Perez, Chris Hopkins, Reid L. Torrance, and C. Randy Hill, published a study in the July 2008 issue of HortTechnology that evaluated direct-seeded onions as an alternative production method. This study evaluated variety, sowing date, and fertility on direct seeding short-day onions in southeastern Georgia. Boyhan explained the impetus behind his research; "Because of the higher cost of transplanting compared with direct seeding, this study was undertaken to evaluate effects of sowing date, variety, and fertility on direct seeding short-day onions in southeastern Georgia." Boyhan added that the research was also aimed at finding ways to lower production costs for growers.
The study results showed that sowing dates in early or mid-October did not affect total, jumbo or medium yields, and sowing onions in late October did not produce sufficient stand or yield to warrant harvesting. Variety also had no affect on yield of direct-seeded onions. Flowering, or seedstems, considered an undesirable characteristic, was significantly greater when the onions were sown in early October, compared to later sowing dates. Neither variety nor sowing date significantly affected plant stand or plant spacing.
"We recommend that growers direct-seed onions in southeastern Georgia in mid-October, plus or minus one week depending on field accessibility. In addition, current fertilizer recommendations for dry bulb onions should be followed. This eliminates all of the cost and resources required for transplant production", stated Boyhan. He noted that onions from transplants will likely predominate in the Vidalia region for the forseeable future. But direct seeding as an alternative method can save growers money. If the labor force necessary for hand harvesting becomes scarce, direct seeding can be a viable and cost-effective alternative.
The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://horttech.ashspublications.org/cgi/content/abstract/18/3/349
Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at ashs.org
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