1996 and for 49 cultivars and lines in west U.S. has a small percentage of 1997. Marketable yield out of storage fall-planted, spring-harvested onions. in January ranged from 478 to 1131 The Pacific northwestern U.S. is a –1 cwt/acre (54 to 127 Mg·ha ) in major onion producing region in the 1996, and from 383 to 912 cwt/acre U.S. In 1997 and 1998, onion was (43 to 102 Mg·ha–1) in 1997. Market- able yields of ‘9003C’, ‘Seville’, ‘El produced on about 20,000 acres Charro’, ‘Sunre 1430’, ‘El Padre’, (8,090 ha) in southeastern Oregon Variety and southwestern Idaho alone, with a ‘Golden Security’, ‘Bravo’, and ‘X 202’ were greater than 1000 cwt/acre total value of about $100 million in (112 Mg·ha–1) in 1996. In 1997, 1997 and $122 million in 1998 (Table marketable yields of ‘Seville’, ‘Bravo’, 1) (USDA, 1999). The onion produc- Trials ‘Quest’, ‘T-433’, ‘9003C’, ‘Goldstar’, tion area is within a radius of 30 miles ‘Superstar’, ‘RNX-10020’, ‘Vision’, (50 km) of Ontario, Ore, on the Snake and ‘Sweet Perfection’ were greater –1 River plain and along the tributaries of than 850 cwt/acre (95 Mg·ha ). Of the Snake River, a region frequently the 30 cultivars evaluated both years, the average marketable yields of referred to as the Treasure Valley. In Yield of Yellow ‘Seville’, 9003C, ‘Bravo’, ‘Quest’, and general, onion bulb yield in the Trea- ‘Sweet Perfection’ were among the sure Valley is greater than in any other Onion Cultivars in highest. Many others showed poten- onion producing area; the average tial for high yields and merit further onion bulb yield in the Treasure Valley Eastern Oregon evaluation. In both years, most bulbs was 648 cwt/acre (72.6 Mg·ha–1) in of all selections graded jumbo [3 to 4 1997 and 538 cwt/acre (60.2 Mg·ha–1) and inch (7.6 to 10.2 cm) diameter] and in 1998 (Table 1) (USDA, 1999). colossal [>4 inch (10.2 cm) diameter], Most onions produced in the Southwestern and only a few cultivars had more Treasure Valley are yellow sweet Span- than 2% medium-size [2.25 to 3 inch ish cultivars, whereas white and red Idaho (5.7 to 7.6 cm) diameter] bulbs. Infection by neck rot (Botrytis allii cultivars made up 6.5% of the crop Munn.) and plate rot [Fusarium during the 1998–99 marketing season oxysporum f. sp. cepa (H. N. Hans.) (IEOOC, 1999). The onions produced Clinton C. Shock, W.C. Snyder & H.N. Hans.] during in the region have a long-standing Joey K. Ishida, storage was more severe in 1996 than reputation for high quality. The on- in 1997, but in general, most cultivars ions are marketed fresh from August Eric P. Eldredge, and showed relatively low levels of these through October, and then out of diseases in both years. Averaged across storage from November through April. Majid Seddigh all cultivars, bolting was evident in Onions are sold out of a few refriger- less than 1% of bulbs in both years. ated storages after April. The primary markets for onions produced in the ADDITIONAL INDEX WORDS. Allium cepa, Treasure Valley are the northern cultivars, breeding lines, market ulb onion is produced on midwest and northeast of the United grade, bulb size, onion neck rot, more than 150,000 acres States (USDA, 1997). Shippers export Botrytis allii, onion plate rot, (60,700 ha) annually in the to off shore markets in the far east. Fusarium oxysporum, bolting, crop B United States (USDA, 1999). The maturity, Treasure Valley These spring-planted long-day United States bulb onion production cultivars are commonly furrow irri- SUMMARY. Potential new onion areas consist of fall planted (spring gated with 44.4 acre-inches/acre (Allium cepa L.) cultivars for commer- harvested) and spring planted (sum- (1128 mm) (Jensen and Simko, 1991) cial production in eastern Oregon and mer harvested) regions. The crop is fall yet onion evapotranspiration at On- southwestern Idaho are evaluated planted and spring harvested primarily tario is about 27.5 acre-inches/acre annually in yield trials conducted at in southern California, Georgia, and (700 mm) (Shock et al., 2000a). Op- the Malheur Experiment Station, Texas, with smaller acreages in Ari- timum irrigation criteria for furrow Oregon State University, Ontario, zona, southeastern states, and else- irrigated onion on silt loam soil in the Ore. Bulb yield and market grade where. These onions are short-day Treasure Valley have been determined were determined in field trials for 63 yellow onion cultivars and lines in cultivars and are marketed from April (Shock et al., 1998). Subsurface drip to August. Onion is planted in the irrigation (SDI) can be used to in- spring in the Pacific northwest U.S. crease onion yield and grade on Trea- Malheur Experiment Station, Oregon State Univer- sity, 595 Onion Avenue, Ontario, Oregon, 97914. (Idaho, Oregon, and Washington), sure Valley sites that are difficult to Funds used for this study were provided in part by the with additional acreage in Colorado, irrigate (Feibert et al., 1995). Subsur- Oregon State Univ. Experiment Station, Project 304. New York, Michigan, Minnesota, Wis- face drip irrigation criteria have been Oregon Agricultural Experiment Station Tech. Paper consin, central California, Utah, and determined to help assure high yields 11464. Financial support from the Idaho Eastern- Oregon Onion Research Committee and onion seed Nevada. These onions are mostly long- of storable sweet spanish onions (Shock marketing companies is gratefully acknowledged. The day cultivars and are marketed from et al., 2000a, 2000b). cost of publishing this paper was defrayed in part by the August to April from storage [Idaho Many onion cultivars are grown payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertise- Eastern-Oregon Onion Committee commercially in the Treasure Valley. ment solely to indicate this fact. (IEOOC), 1999]. The Pacific north- Open pollinated yellow sweet spanish ● July–September 2000 10(3) 613 VARIETY TRIALS varieties were the standard in the re- from decay occurring during storage. tario, Ore. Fields in both years had gion, but hybrid cultivars have gained Since 1972, established cultivars previously been planted to wheat, and popularity during the last 2 decades. and new onion lines for commercial had 1.5% organic matter and a pH of Currently most of the cultivars grown production in eastern Oregon and 7.4. Before fall plowing, 100 lb/acre –1 in the region are hybrids, which are Idaho have been evaluated in repli- (112 kg·ha ) of P2 O5, and 20 to 50 generally more uniform and higher cated yield trials conducted at the lb/acre (22 to 50 kg·ha–1) N were yielding. Seed companies are continu- Malheur Experiment Station near broadcast. The wheat stubble was ally developing new cultivars. Besides Ontario, Ore. This paper presents bulb shredded and the field deep-chiseled, bulb yield, many other characteristics yield evaluated after storage for culti- disked, irrigated, moldboard-plowed, of these cultivars need to be evaluated vars of yellow onions from variety yield roller-harrowed, and bedded in the across years and locations in order to trials conducted at Malheur Experi- fall. At bedding, the field was fumi- know which cultivars are best for any ment Station in 1996 and 1997. For gated with 18 gal/acre (168 L·ha–1) of particular location. Important charac- simplicity of the discussion, both the Telone C-17 (Dow Chemical Co., teristics include maturity rating, po- established cultivars and the experi- Midland, Mich.) (77.9% 1,3- tential for bolting, bulb size, and sus- mental lines on the verge of release are dichloropropene + 16.5% chloropicrin ceptibility to neck rot and plate rot referred to as cultivars. Maturity rating + inert ingredients) and left until spring diseases. and the potential of all cultivars for without further tillage. Bolting (flowering) is induced by bolting is reported. Bulb yield and In March of each year, the beds exposure to cold temperatures market grade, as determined out of were harrowed down and sprayed with (Brewster, 1994). Bolting is a highly storage in January following each har- 3 lb/acre (3.3 kg·ha–1) a.i. of DCPA undesirable cultivar characteristic in vest, are presented. Cultivar suscepti- banded 11-inch (28-cm) wide along bulb production. Neck rot and plate bility to neck rot and plate rot during the top of the beds. The DCPA was rot are the most important onion dis- storage is evaluated. incorporated the next day with a bed eases in the Treasure Valley, and losses harrow. Onion seeds used were of 63 of greater than 50% of bulb yield can Materials and methods cultivars from 14 companies in 1996, occur for some cultivars from indi- The trials were conducted on and of 49 cultivars from 15 companies vidual fields in a few years. Infection by Owyhee silt loam (coarse-silty, mixed, in 1997. Seeds were planted in mid- both fungi occurs in the field, with loss mesic Xerollic Camborthid) near On- April on 22-inch (56-cm) single-row Table 1. The top ten states and areas for onion bulb yield (all types-all seasons), land harvested, and total value in 1977 and 1978.z Land Avg Total State or harvested State or bulb yield State or value area (acre)y area (cwt/acre)x area ($1000) 1997 California 36,200 Treasure Valleyw 648 California 143,869 Treasure Valleyw 20,200 Nevada 540 Treasure Valleyw 100,444 Georgia 15,800 Washington 520 Georgia 88,990 Colorado 15,300 Utah 485 Washington 61,594 Washington 14,400 New Mexico 470 Colorado 49,289 New York 12,200 Oregon (west) 450 New Mexico 43,315 Texas 11,800 California 441 Texas 41,539 Oregon (west) 7,400 Ohio 415 New York 39,276 New Mexico 6,400 Wisconsin 390 Oregon (west) 28,603 Michigan 6,100 Arizona 355 Michigan 13,840 Total 145,800 Mean 471 Total 610,759 1998 California 36,800 Treasure Valleyw 538 California 170,902 Washington 20,350 Washington 492 Treasure Valleyw 122,540 Treasure Valleyw 20,000 Arizona 470 Washington 108,738 Colorado 16,000 New Mexico 460 Texas 90,226 Texas 15,400 California 440 New York 77,844 Georgia 13,900 Oregon (west) 440 New Mexico 68,722 New York 12,500 Utah 440 Oregon (west) 51,638 Oregon (west) 7,500 Nevada 440 Georgia 43,056 New Mexico 7,200 Wisconsin 380 Michigan 39,485 Michigan 4,500 Ohio 310 Utah 10,692 Total 154,150 Mean 441 Total 783,843 zBased on USDA (1999).