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or multiplier (A. cepa) and . By far, most of the cultivated onions fall into the Common Group, noted for producing a single bulb per plant. Onions are also classed by their response to day length. Short-day on- ions require a relatively short day length Crop to trigger bulbing. In the growing region, bulbing begins at day lengths slightly over 11 h. In compari- son, intermediate-day and long-day Reports onions bulb at day lengths that exceed 13 and 14 h, respectively (Brewster, 1994); however, the exact day length required for bulb initiation may vary from season to season and from field to field within sea- consistent as expected for extending sons, because several other factors includ- Vidalia Onions— onion shelf life. In addition, some grow- ing, temperature, leaf area, variety, and ers have expressed concern over some intercepted light significantly affect the new varieties being too hot to be called process. Within the short-day varieties Production in Vidalia onions. Other varieties have in- grown in the Vidalia region, differential creased problems with late season dis- bulbing responses result in onions being Southeastern eases. Vidalia onions, however, remain harvested from the beginning of April to one of the bright spots in American the beginning of May in most years. Even agriculture by providing good returns though factors other than day length influ- for the producers. Although somewhat ence bulb development, classifying onion 1 uncertain, the Vidalia onion’s future varieties according to day length response George E. Boyhan and remains promising. For the industry to is important to seed companies and grow- Reid L. Torrance2 continue to prosper issues concerning, ers because it indicates varietal adaptation increased competition, production prob- to specific regions of production. The lems including variety selection, and use USDA National Agricultural Statistics ADDITIONAL INDEX WORDS. cepa, of CA storage have to be addressed. Service uses the classification of spring spring nonstorage onions, short-day Vidalia onions are also referred to nonstorage, summer nonstorage, and onions, dry-bulb onions, Granex, as yellow onions, salad onions, green summer storage onions to report onion Grano, Bermuda onions, and dry bulb onions. In order to statistics (USDA, 2000). This roughly be a Vidalia onion they must be a yellow coincides with the short-day, interme- outheastern Georgia is ideal for Granex type. Salad and green onions diate-day, and long-day classes. sweet onion (Allium cepa) pro refers to immature onions. They are The short-day onions grown in S duction. This region is noted for comparable to , however they southeastern Georgia bulb relatively its mild winters, low sulfur soils, and tend to be longer in total length with early, usually during late February or abundant water supply. Vidalia onions larger leaves and an expanded bulb, early March as the day length increases. with their national reputation for mild- about 1 inch (2.5 cm). For this reason, seeds of such varieties ness have dramatically increased in avail- The objective of this article is to are sown in the fall when days are get- ability in the last 10 to 12 years. Several highlight the Vidalia onion industry, ting shorter. This will enable seedlings factors have contributed to this increase and to describe its past, present and to emerge and develop sufficient leaf including; national name recognition, future with respect to production prac- area before bulbing is initiated in the regulatory control of the Vidalia name, tices, issues of concern, and marketing. spring. Short-day onions planted in the ideal region of production, Marketing spring would begin to bulb almost im- Order 955 (USDA, 1989), and the Classification mediately resulting in very poor yields. adoption of controlled atmosphere (CA) Onions are monocots and mem- Origin and variety storage. These factors have resulted in a bers of the Alliacae family, which in- 3-fold increase in production since 1989 cludes (A. cepa), (A. development (USDA, 2001). ampeloprasum), japanese bunching on- Onions have been known to be in The growth of the Vidalia onion ion (A. fistulosum), shallots (A. cepa), cultivation for at least 5000 years. They industry has not been without challenge (A. schoenoprasum), elephant are native to the Eurasia region of Tur- or controversy. Wide fluctuations in garlic (A. ampeloprasum), and a few key, Afghanistan, Iran, Pakistan, and performance from one year to the next ornamental types (Brewster, 1994). into northeastern China and Mongolia have caused CA storage not to be as Onions can be organized into two (Brewster, 1994). Wild are typi- broad groups, the Common Onion cally found in open arid regions with 1University of Georgia, Dept. of Horticulture, East Group and the Aggregatum Group cool climates. Georgia Extension Center, P.O. Box 8112, GSU, Statesboro, GA 30460. (Brewster, 1994). The Aggregatum Considered a cool-season crop, 2Tattnall County Cooperative Extension Service, P.O. Group is noted for producing clusters of onions have been adapted to a wide Box 580, Reidsville, GA 30453. bulbs. The two main entries are potato geographic area through selection for

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CropRpt 196 2/27/02, 9:50 AM States were ‘Valencia’, which came from ers considered these varieties to be too Spain and ‘White Bermuda’, which came pungent to market as Vidalia onions. from Italy via Bermuda (Goldman and The elevated pungency levels were es- Havey, 1998). These early populations pecially troublesome because these vari- were the foundation for short-day on- eties would be the first onions offered to ions in New Mexico, , and Geor- the public in the spring. Many have gia. ‘Valencia’ was ultimately the source suggested that it is not the pungency, for ‘Texas Early Grano 951C’, which but rather bitter off-flavors, that are the was one of the parents for the hybrid problem with the Japanese varieties. ‘Granex YB986’. A selection of ‘Excel’, Concerns related to the flavor of became the other parent in the ‘Granex’ these early Japanese overwintering vari- hybrid (Goldman and Havey, 1998). eties prompted the Georgia Depart- The ‘Granex’ name is conjoined from ment of Agriculture in 1997 to restrict the names ‘Grano’ and ‘Excel’. This Vidalia onion varieties to 12 varieties Fig. 1. Granex onion pedigree. hybrid became the basis for the Vidalia (Table 1). These varieties were: Sweet onion industry (Fig. 1). Vidalia, Granex 33, Savannah Sweet, bulbing response to day length. Onions Variety development has contrib- Pegasus, Granex F1, Sweet Success, have been adapted to most regions of uted to the release of several varieties Dessex, Southern Belle, Southern the world from the most northern ar- adapted to the Vidalia onion growing Honey, Rio Bravo, Mr. Max, and Ado- able climes to the tropics. region. One of the most popular early nis. In 1999, this issue was again brought The biennial nature of onions poses varieties, Granex 33, is still grown today. to the fore and three varieties: challenges to plant breeders. In addi- The industry’s success, over the past de- Queen, Spring Express, and Sweet Dixie tion, breeding efforts must be specific to cade, has fostered the release of several new were identified by the Georgia Depart- particular regions according to day varieties. Currently about 50% of the ment of Agriculture as unacceptable length requirements. Selection of new acreage is planted to ‘Sweet Vidalia’, and were not allowed to be grown. In varieties is therefore time consuming which is an early to midseason onion. addition, rules were adopted that man- and difficult. The process can be accel- In the mid-1990s, a new type of dated the University of Georgia was to erated with seed-to-seed production, onion was introduced to the Vidalia make variety recommendations to the which forces the plant to produce seed onion industry. These Japanese over- Georgia Department of Agriculture based in the same season it is sown. This can be wintering onions had two important on variety trial including pyruvate analyses troublesome because ease of seedstem advantages over the traditional varieties. and taste panel evaluations (Georgia De- formation (bolting) is considered unde- They were 2 weeks earlier than previous partment of Agriculture, 2001). sirable in the bulb crop. On the other varieties and they had very good foliar In 2000, the Georgia Department hand, because bulb quality and yield are disease resistance. However, many grow- of Agriculture attempted to expand the of utmost importance in the breeding process, and seedstems are considered Table 1. List of current and proposed Vidalia onion varieties. objectionable, selection for bolting re- sistance often results in plants with poor Variety Source Season seed producing ability. Adonisz Harris Moran The 20th century has seen the de- Cyclops (XP 6995) Asgrow Late velopment of modern plant breeding Dessexz Sunseeds techniques, which have resulted in DPS 1032y,x D. Palmer Midseason tremendous advancements in yield and Granex 33 Asgrow Midseason quality of onions. The discovery of male Mr. Maxz Sunseed sterility in onions in 1925 led to a method Pegasus Asgrow Late y,x of creating F1 hybrid onions (Goldman PS 7092 Petoseed Midseason and Havey, 1998). Male-sterile plants can Rio Bravoz Sunseeds be interplanted with pollenizer plants re- Savannah Sweet Petoseed Midseason sulting in large-scale production of F1 seed Southern Belle D. Palmer Midseason precluding the need for controlled hand Southern Honey D. Palmer Midseason

pollinations. F1 hybrids have advantages Sunseeds Improved Granex F1 Sunseeds Midseason over open-pollinated varieties in that supe- Sweet Advantage (1058)y D. Palmer Early rior varieties can be developed more quickly Sweet Melissa (Sunex 1519) Sunseeds Midseason and they exhibit heterosis or hybrid vigor Sweet Melody Sunseeds Midseason (Simmonds, 1979). In addition, they tend Sweet Success Sunseeds Midseason to be more uniform in their performance, Sweet Vidalia Sunseeds Midseason which is useful in commercial production WI-3115y Wannamaker Early particularly with mechanical harvesting. WI-609y Wannamaker Early The modern Granex varieties zDiscontinued varieties. grown in the Vidalia region have their yProposed additions to the variety list by the University of Georgia for 2001–02 season. origin from Mediterranean onion vari- xProposed additions by the Georgia Department of Agriculture for the 2001–02 season. wAsgrow (Asgrow Vegetable Seeds, Oxnard, Calif.); D. Palmer (D. Palmer Seed Co., Inc., Yuma, Ariz.); Harris eties. Two important open-pollinated Moran (Harris Moran Seed Co., Modesto, Calif.); Petoseed (Petoseed, Oxnard, Calif.); Sunseeds (Sunseeds Co., populations imported to the United Morgan Hill, Calif.); Wannamaker (Wannamaker International, St. Mathews, S.C.).

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variety list with inclusion of seven addi- agents, the Vidalia onion crop was esti- and could be grown only in a specifically tional varieties; however, after holding mated to be valued at $94,487,900 designated area of Georgia. The desig- hearings and failing to get a clear man- (University of Georgia, 2000) nated Vidalia growing region includes date from the growers, the Georgia 12 counties in their entirety and parts of Department of Agriculture decided to Vidalia onion history 8 others. The state of Georgia defined maintain the original 12 varieties while Short-day onion production be- the Vidalia onion growing region, which including three additional varieties, gan in southeastern Georgia in 1931 includes all of Appling, Bulloch, Can- Cyclops, Sweet Melody, and Sweet (D. Bland, personal communication). dler, Evans, Emanuel, Jeff Davis, Mont- Melissa based on University of Georgia The first grower to produce sweet on- gomery, Tattnall, Telfair, Toombs, recommendations. Several seed compa- ions was a local grower, Mose Coleman. Treutlen, and Wheeler counties, as well nies and growers promptly sued the He was able to produce and sell sweet as, parts of Bacon, Dodge, Jenkins, Georgia Department of Agriculture al- onions for the unheard of price of $3.50 Laurens, Long, Pierce, Screven, and leging they did not follow their own for a 50-lb (22.7-kg) bag. Considering Wayne counties (Fig. 2). Over the years, rules regarding the inclusion or exclu- 400 bags/acre (22.4 t·ha–1) as an aver- this legislatively designated area has be- sion of varieties and won the case. As a age yield, this was a fabulous return, come popularly known as the onion result there were no restrictions on vari- especially with the advent of the Great belt. For growers to market onions as eties for the 2000–01 growing season. Depression. Other growers soon saw Vidalia onions they must grow them in With the completion of 3 years of the value and potential profitability of fields within this region. trials, the University of Georgia has these onions and began growing them. Although this legislation gave the recommended the inclusion of five ad- A farmer’s market was constructed onion industry protection within Geor- ditional varieties; DPS 1032, PS 7092, in Vidalia, Georgia in the 1940s to help gia, it did not give the industry protec- Sweet Advantage (1058), WI-3115, and growers sell their produce. In addition, tion in the rest of the U.S. However, in WI-609. Two of these varieties, WI- Vidalia was strategically located on the 1989 the industry obtained national pro- 3115 and WI-609 are early Japanese crossroads of some of the most impor- tection with Marketing Order 955 (USDA, overwintering varieties. The Georgia tant preinterstate north–south routes. 1989). This order gave recognition and Department of Agriculture has decided Word spread among travelers driving protection to Vidalia onions and to the to adopt only two of the University of through Vidalia about those mild sweet state mandated onion-growing region. Georgia’s recommendations, ‘DPS onions. Piggly Wiggly, a well know This marketing order also established the 1032’ and ‘PS 7092’. This will extend supermarket chain, also maintained a Vidalia Onion Committee, which collects the list of acceptable varieties to 17. In warehouse distribution center in Vidalia monies from growers based on volume of addition to the 3 years of University of and purchased these onions when in onions sold. This money is used for pro- Georgia trials and testing for pungency, season for distribution in their stores. motional efforts and for research that the Georgia Department of Agriculture All of these factors contributed to the benefits the production and marketing based their decision on the inclusion of development and growth of this indus- of Vidalia onions. Since establishment 1 year of taste panel evaluations. try. By the 1970s there were about 600 of the Vidalia Onion Committee, more acres (243 ha) of production. than $0.5 million has been funneled Production statistics Initially the sweet Vidalia onions into onion research, primarily through Total onion acres harvested in the were marketed primarily in Georgia and the University of Georgia. United States was 169,200 acres (68,473 bordering states. However, as the acre- In 1990 the industry began adopt- ha) in 1999, an increase over the 166,340 age increased, growers saw the need to ing CA storage for onions. This tech- acres (67,315 ha) harvested the previ- develop national markets for Vidalia nology, borrowed from the apple (Malus ous year (USDA, 2000). The total value onions. Annual festivals were established ×domestica) industry, relies on a low of the onion crop in the United States in both Vidalia and Glennville, Ga. oxygen (3%), high carbon dioxide (5%) was $654,282,000 in 1999. According Through the remainder of the 1970s refrigerated atmosphere to preserve and to the USDA National Agricultural Sta- and into the 1980s the industry grew to extend the marketing season of Vidalia tistics Service, Georgia produced 14,500 about 4,000 acres (1,619 ha). Because onions. Instead of being marketed only acres (5,868 ha) of spring onions, some- of the profitable market premiums paid during the spring, CA storage enables what less than the 15,765 acres (6,380 for Vidalia onions, some growers began growers to extend their marketing sea- ha) accessed through the marketing buying onions from Texas, rebagging son into the fall. Currently there is order by the Vidalia Onion Committee. them in Vidalia onion bags, and selling enough storage capacity in the region to The 14,500 acres represents almost 39% them as Vidalia onions. Although up- store 20 million bags of onions. This of the total spring onion acres grown in setting many, this practice was not ille- represents about half of the annual the United States. If the summer gal at the time. Growers asked the Geor- Vidalia onion production in Georgia. nonstorage onions are included, Vidalia gia legislature to regulate marketing of By dramatically increasing the duration onion acreage drops to 28% of the total. Vidalia onions to prevent such practices. of the marketing season, CA storage is a The value of the Vidalia onion crop was As a result, a standard was set for Vidalia major factor contributing to the in- reported as $74,661,000 in 1999 which onions. In 1986, the Georgia Depart- crease in Vidalia onion acreage from represents a little over 40% of the total ment of Agriculture was given owner- 4,900 acres (1,983 ha) in 1989 to its value of the spring onion crop and a ship of the Vidalia name for the purpose current level of 15,000 acres (6,070 ha) little over 26% of the spring and summer of regulating marketing of these unique (USDA, 2001). nonstorage onion crop grown in the onions. In addition, laws were passed Another important development United States. In 2000, based on a mandating that onions sold as Vidalias in the Vidalia onion industry has been survey of the Georgia county extension had to be a Granex-type the adoption by some growers of me-

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CropRpt 198 2/27/02, 9:50 AM sulfur means there is less of these precur- sors formed and irrigation water ensures maximum water content in the onions. This results in some of the mildest on- ions produced anywhere in the world. Recently there has been an in- creased interest in the health benefits of various compounds found in alliums, particularly garlic. Onions also produce many of these compounds that have been implicated in enhancing human health. Properties of onions that are thought to hold the greatest potential for human health benefits included their hypocholesterolemic, antioxidant, and fibrinolytic effects (Augusti, 2000). Onion oils have also been shown to increase serum insulin levels in humans with lowered blood sugar. Research continues in these areas. Crop production and management High levels of residual soil sulfur or large applications of sulfur fertilizer par- ticularly during the latter part of the crop cycle can result in pungent onions (Granberry et al., 1987). The sandy loam Coastal Plain soils of southeastern Georgia are naturally low in sulfur, typi- cally less than 0.001 ppm (mg·L–1). In addition, southern Georgia sits on top of the Floridan aquifer, an abundant source of low-sulfur water. Irrigation is Fig. 2. Onion growing region of a good source of C. a necessity for production of mild Vidalia southeastern Georgia, which encom- Onion flavor and the underlying onions. In the Georgia onion belt, irri- passes 12 whole counties and parts of chemistry is both interesting and com- gation water is supplied by deep wells, 8 others. plex. Onion flavor is primarily the result and applied overhead primarily through of the hydrolysis of S-alk(en)yl cysteine fixed center-pivot systems. These sys- chanical harvesting. Since 1997, some sulfoxide to sulfenic acid, which quickly tems are relatively inexpensive and easy acreage has been mechanically harvested. rearranges into a myriad of strongly to operate. The downside of using these Although several of the larger growers flavored compounds (Wall and Corgan, fixed systems is onions are generally not have invested in harvesting equipment 1992). This hydrolysis occurs in the pres- rotated in production, but are continu- and modified their packing shed opera- ence of alliinase, which is released when the ally produced on the same site. This tions to accommodate this technology, onion is macerated. When eaten, onions contributes to increased incidence and the bulk of the acreage continues to be do not impart a pungent flavor immedi- severity of soil borne diseases such as hand harvested. Complete adoption of ately, however, several seconds after the pink root (Phoma terrestris). Vidalia mechanical harvesting across the onion onion is chewed, pungency is detected as onions are a long season crop requiring belt has not occurred because of the the alliinase is released and hydrolysis of intensive management, high fertility, high capital costs, the fact that smaller the sulfur-containing precursors begins. and a great deal of labor. Vidalia onion fields do not lend themselves to large Pungency intensity depends on the level production encompasses the produc- harvesting equipment, and continued of S-alk(en)yl cysteine sulfoxide precur- tion of three different crops; transplant technical problems. sor. Whether mild or hot, the unique production, salad onion production, and flavor of onions is their most important dry-bulb onion production. Composition and uses attribute. Production can begin as early as Short-day onions are high in water Vidalia onions like all short-day late July or early August with land prepa- and low in total solids. Nutritionally, onions are high in water and low in ration for planting salad onions. Salad they have no fat or cholesterol, but are solids, which means there is a relatively onions are produced either from direct- a source of including low level of the S-alk(en)yl cysteine sulfox- seeded onions or from transplants simple . A single medium sized ide precursor resulting in mild onions. (Boyhan et al., 1999). Land preparation onion has about 60 calories, 2 g of Vidalia onions also benefit from the low begins with deep turning to bury the protein, 14 g of carbohydrates, and 3 g sulfur soils in southeastern Georgia and previous crop litter, application of lime of fiber (Richter, 2000). Onions are also the abundance of irrigation water. Low if needed, and incorporation of metam-

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sodium, to control dampening-off and to the field beginning the week before Transplanted onions are fertilized weeds. Although there are several dif- Thanksgiving and continuing until throughout the growing season begin- ferent fertility programs used by grow- Christmas. Transplants are pulled and ning immediately after transplanting ers the following is typical of production bundled with 50 to 80 plants per bundle. with a broadcast application of 150 lb/ practices for Vidalia onions. Preplant The tops, which represent 50% or more acre of diammonium phosphate. This is applications of 400 to 800 lb/acre (448 of the growth of the plants, are removed followed with two broadcast applica- to 897 kg·ha–1) of 5–10–15 fertilizer resulting in a 4 to 6 inch (10 to 15 cm) tions of 150 lb/acre of 6–12–18 (6N– (5N–4.4P–12.5K), which contains 4% transplant before transporting to fields 5.2P–14.9K), which contains 4% sulfur to 9% sulfur, are incorporated before for planting. at 4 and/or 6 weeks after transplanting, sowing. Salad onions are sown on beds Fields to be used for dry-bulb on- and, by two broadcast applications of or panels (as they are called locally), ion production are prepared 2 to 4 CaNO3 at 200 lb/acre 10 weeks and 12 which are slightly raised and formed weeks before transplanting by deep turn- weeks after transplanting. All the sulfur during the final step in land preparation. ing to bury any previous crop residue. fertilizer is applied by the end of January These beds or panels are prepared 6 ft Plant beds are prepared by chiseling, and all the fertilizer is applied by the end (1.8 m) on center (all equipment in the disking, and/or rotovating. A typical of February. The earliest onions are onion belt is based on 72-inch (183- fertility program begins with 400 lb/ ready for harvest in early April. cm) tractor wheel spacing). Salad on- acre of 5–10–15, which includes 4% ions are sown four rows to the bed with sulfur applied preplant and incorpo- Diseases and insects a between row spacing of 14 to 18 rated. In addition, chlorpyrifos is ap- Insects are not generally a problem inches (35.6 to 45.7 cm) and an in-row plied to reduce populations of soil borne through the winter. As mentioned pre- plant spacing of 1 to 2 inches (2.5 to 5.1 insects such as onion maggots (Delia viously, soilborne insects, including cm) when direct seeded. When they are antiqua) before transplanting. onion maggots, seed corn maggot seeded for transplant production of salad A specialized piece of equipment (Delia platura), cut worms (species of onions, 40 to 70 seed are sown per linear called a pegger is used for final bed prepa- the Noctuidae family), and mole crick- foot (0.3 m). Many growers apply 150 ration and to form the holes where the ets (Scapteriscus acletus), are controlled lb/acre (168 kg·ha–1) of diammonium onions will be transplanted (Fig. 3; color with a single application of insecticide phosphate [(NH4)2 H2PO4] immedi- version at http://www.uga.edu/hort/ before transplanting. ately after sowing. However recent stud- hortpub/HT1540.html). The desired Thrips, which can become a prob- ies have shown that high phosphorus spatial arrangement is to have four rows lem in late winter and early spring, are fertilizers are not required at this time planted 14 to 18 inches (35.6 to 45.7 cm) controlled by one to two applications of due to high soil temperatures coupled apart with an in-row spacing of 4.5 to 6 an appropriate insecticide. Two thrip with high residual phosphorus levels. inches (11.4 to 15.2 cm) (Fig. 4; color species are found on Vidalia onions, After seeding, beds are kept evenly moist version at http://www.uga.edu/hort/ western flower thrips (Frankliniella until seed germination occurs. This of- hortpub/HT1540.html). All onions occidentalis) and tobacco thrips (F. ten requires irrigation with a 1/10 inch grown from transplants are set by hand. fusca). Interestingly, onion thrips (Thrips (0.25 cm) of water several times a day. Mechanical transplanters are too slow to tabaci) occur in very low numbers on Two to three additional broadcast ap- meet the crop establishment time frame. Fig. 3. Onion pegger used for final plications of calcium nitrate (CaNO3) Growers wish to have the entire crop set bed preparation and to mark holes –1 are applied at 200 lb/acre (224 kg·ha ) within 4 to 6 weeks. where the onions will be planted. beginning 4 weeks after seeding. Salad onions are ready for harvest in 12 to 14 weeks. Overall, salad onions represent a very small part of the onion crop, but on a per acre basis they can be very profit- able, especially for those growers that market them at retail. Transplant production begins with seeding of onions on beds in mid to late September (Boyhan et al., 2001). Trans- plant onion production is similar to salad onion production; however, the seed are sown later and are grown only for 8 weeks before transplanting. Land preparation, fertilization, and fumiga- tion are similar to salad onions with perhaps one less fertilizer application. For producing dry bulb transplants, seed are sown at a rate of 40 to 70 per linear foot. Spacing is similar to salad onions with the exception of a few growers who plant five rows per bed instead of four. The dry bulb onions, which make up the bulk of the crop, are transplanted

200 G April–June 2002 12(2)

CropRpt 200 2/27/02, 9:50 AM tops down) before harvesting. Vidalia onions are generally harvested before this point and in fact, some varieties would be completely unusable if al- lowed to reach this level of maturity. Having some erect green tops has hin- dered the more rapid adoption of me- chanical harvesting by growers. How- ever, current research continues to ad- dress this problem. Finally, there are some small fields where mechanical har- vesting will never be adopted. Onions are graded into size classes based on USDA standards for Bermuda- Granex-Grano-type onions. Vidalia on- ions are primarily sold under two size classes, mediums and jumbos. Medi- ums have a minimum diameter of 2 inches (5.1 cm) and a maximum diam- eter of 3.25 inches (8.25 cm). Jumbos have a minimum diameter of 3 inches (7.6 cm) and no maximum size. There is also a colossal size that is occasionally sold with a minimum diameter of 3.75 Fig. 4. Typical field layout of four detect until the onions are removed from inches (9.5 cm) (USDA, 1995). rows on a bed or panel. storage at which time the bulbs exhibit the problem and are rendered unsalable. This Processing and marketing Vidalia onions. Scouting is an impor- disease is highly variable from year to year Vidalia onion growers and packers tant part of thrip control, because their and is associated with damage to the on- are required to register with the Georgia occurrence can vary widely from year to ions. This damage can be from cold Department of Agriculture before the year. Spraying begins when an average weather or rough handling. In some beginning of the harvest season. They of five thrips are present per plant. years growers have lost 50% to 70% of are required to list the name and address Disease control during the winter the onions coming out of storage. of their farm as well as the varieties they includes the regular use of fungicides will be selling. In addition, they are such as chlorothalonil and dithane. Harvesting and handling required to have the onions inspected. Copper fungicides are also applied peri- Vidalia onions are primarily harvested Table 2 gives a breakdown of the odically to control bacterial diseases. by hand. Plants are undercut when bulbs estimated cost of production as well as an The incidence and severity of vari- reach harvest maturity, as indicated by estimate of the return on a 40-lb (18.1-kg) ous onion diseases depend on the weakened neck tissue, which can result in box of Vidalia onions. With an average weather and time of year. Rainy, humid tops falling over. After undercutting they yield of 500 boxes/acre (22.4 t·ha–1) the weather will aggravate disease prob- are left in the field for 1 to 3 d to dry. Then return is $1,990/acre ($4,917/ha). lems. In recent years, bacterial diseases the tops and roots are clipped and the Vidalia onions are packaged fresh including bacterial streak (Pseudomonas onions are bagged (Fig. 5; color version at in a number of different size boxes and viridiflava), center rot (Pantoea http://www.uga.edu/hort/hortpub/ bags. Until recently, prices were quoted ananatis), and sour skin (Burkholderia HT1540.html) before transporting to the based on a 50-lb bag of jumbos or medi- cepacia) have become a major concern packing shed where they are unloaded and ums. Recently this has changed and prices among growers. Bacterial streak gener- heat cured at 95 to 105 °F. (35 to 40 °C) are now quoted on a 40-lb box. This ally is seen during the winter when the for 1 to 3 d before they are graded and change was requested by the chain stores, weather is cool and humid. Center rot packaged. which were interested in a lighter con- occurs as the weather warms from late Over the past 5 years mechanical tainer for ease of handling. Onions are winter to harvest. Sour skin is a disease harvesting has become more prevalent still available in a variety of bag and box of late varieties and usually requires in the Vidalia onion region. Tradition- sizes from 5 (2.3 kg) to 50 lb. temperatures above 85 °F (29 °C). ally, mechanical harvesting was avoided Along with the wholesale market, Botrytis neck rot (Botrytis allii) has because growers believed it would be Vidalia onions are direct marketed at become more of a concern because of too damaging to the onions. However, retail by several growers. Mail order the increased use of CA storage. This recent studies have shown that me- catalogs and Internet marketing have disease enters the bulb either at the soil chanical harvesting is as effective or in been quite successful. In addition, Vidalia line or through the cut surface when the some cases more effective, than hand onions are used to make a variety of tops are removed (Lacy and Lorbeer, harvesting in preventing damage to the processed dressings and sauces, which 1995). In the past it has not been that onions. In addition, the use of some are marketed by retailers and directly troublesome because no one used CA mechanical harvesting equipment in from growers. Vidalia onions are also storage. With CA storage the fungus en- other onion production areas has relied processed into frozen onion rings and ters the bulb and is all but impossible to on a completely mature crop (all the pieces. Cracker Barrel Restaurants, for

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Disease control, particularly, those caused by bacteria, continues to be a con- cern. New varieties and new methods of control need to be developed to help minimize losses from bacterial diseases. The Vidalia onion industry has been a great success in an agricultural economy that has faced many setbacks in recent years. Consistent production of some of the mildest onions in the world has allowed this industry to grow, prosper, and command a premium in the mar- ket. Finally, although there are a num- ber of challenges facing the industry, the future appears bright.

Literature cited Augusti, K.T. 2000. The role of garlic and onions in health management. Alliums 2000. 3rd Intl. Symp. Edible Alliaceae. 29 Oct–3 Nov. 2000. p. 19.

Boyhan, G.E., D.M. Granberry, and W.T. Kelley. 1999. Green onions. Univ. Ga. College Agr. Environ. Sci. Circ. 821. Fig. 5. Bagged onions ready for growth of the industry. Boyhan, G.E., D.M. Granberry, and W.T. Kelley (eds.). 2001. Onion production guide. Univ. Ga. College Agr. transport to the packing shed. The Vidalia onion industry contin- Environ. Sci. Bul. 801. ues to evolve and address new prob- Brewster, J.L. 1994. Onions and other vegetable alli- example, features Vidalia onion rings. lems. The industry faces increased com- ums. CAB Intl., Wallingford, UK. Vidalia onions have traditionally com- petition not only from other states but Georgia Department of Agriculture. 2001. Rules of manded a premium in the marketplace. also from South American production. Georgia Department of Agriculture. Chapter 40-7-8. This is due to the mild nature of short-day South American production costs are Additional regulations applicable to Vidalia onions. Ga. onions coupled with the ideal conditions much lower than Georgia’s and this Dept. of Agr., Atlanta. for onion production in southeastern Geor- poses a serious threat to the continued Goldman, I.L. and M.J. Havey. 1998. History and gia. Georgia has consistently produced growth and success of the Vidalia onion pedigree of public onion releases in the United States. some of the mildest onions in the world. industry. Researching and developing Proc. 1998 National Onion (and other Alliums) Res. Conf., Sacramento, Calif. 10–12 Dec. 1998. p. 25–34. This is borne out by the prices received for new production methods that reduce Vidalia onions, which sold for $27.10/ costs are high priorities. Granberry, D.M., D. Smittle, W. McLaurin, and R.L. Shewfelt. 1987. The effects of calcium sulfate on leaf and cwt ($0.60/kg) in 1999 compared to the The development of improved va- bulb tissue, sulfur content and on pungency of the range of $5.53/cwt to $24.40/cwt rieties and the evaluation of Japanese Vidalia onion. Proc. Natl. Onion Res. Conf. 10–11 Dec. ($0.12/kg to $0.54/kg) for spring and overwintering onions continues to be 1987. p. 27–32. summer nonstorage onions produced in important issues. Disease resistance, Lacy, M.L. and J.W. Lorbeer. 1995. Botrytis neck rot, other states (USDA, 2000). quality parameters (particularly mild fla- p. 18–19. In: H.F. Schwartz and S.K. Mohan (eds.). vor), yield, and harvest dates are the Compendium of garlic and onion diseases. API Press, St. Paul, Minn. Conclusions major parameters currently being ad- The Vidalia onion industry has been dressed by the seed companies. Richter, H. 2000. Fresh produce guide. Try-Foods quite successful particularly in the last 10 to The success of CA storage has been, Intl., Apopka, Fla. 12 years. The adoption of CA storage, at times, inconsistent and below origi- Simmonds, N.W. 1979. Principles of crop improve- which has extended the marketing win- nal expectations. Botrytis neck rot, and ment. Longman Inc., New York. dow, federal/state recognition and pro- other storage diseases, can be serious Univ. of Georgia. 2000. 2000 Vegetable acreage esti- tection, and check-off funds resulting in problems in some years. Research on mates. Univ. Ga., Athens. increased advertising and name recogni- identifying diseased onions before they U.S. Department of Agriculture. 1989. Marketing or- tion have all contributed to the success and enter storage is underway. der: Vidalia onions grown in Georgia. Code Fed. Regulat., Chapter IX, Part 955. USDA, Wash., D.C.

Table 2. Estimated costs and return on producing a 40-lb (18.1-kg) box of U.S. Department of Agriculture. 1995. U.S. standards Vidalia onions. for grades of Bermuda-granex-grano type onions. USDA, Wash., D.C.

Parameter $ U.S. Department of Agriculture. 2000. Vegetables 1999 summary, p. 31–34. USDA, Wash., D.C. Preharvest variable cost per box 2.55 Harvest and marketing cost per box 3.68 U.S. Department of Agriculture. 2001. Georgia crop Fixed costs per box 0.63 estimates. USDA Natl. Agr. Stat. Serv., Wash., D.C. Total budgeted cost per box 6.86 Wall, M.M. and J.N. Corgan. 1992. Relationship be- USDA National Agricultural Statistics Service estimated return per box 10.84 tween pyruvate analysis and flavor perception for onion pungency determination. HortScience 27:1029–1030. Net profit 3.98

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