f 998 National (and other ) Research Conference Sacramento, California, USA

and Information Center y University of California, Davis http:flvricMCdavis.edu .' •■ ..•■(•. '•■ •.

: ^*5M .

I^SRI Organizing Committee

AI Burkett, Seminis Vegetable Seeds Roy "Tule" Kreizenbeck, Rio Colorado Seeds, Inc. Tom Ikesaki, Empire Research David Visher, Vegetable Research and Information Center, UCD Kitty Schlosser, Vegetable Research and Information Center, UCD Ron Voss, Vegetable Crops Department, UCDavis (Chair)

Sponsors f Asgrow Vegetable Seeds Basic Vegetable Products Christopher Ranch m Colusa Produce Company Crookham Seed Company De Francesco Company & Sons, Inc. Emerald Seed Company Empire Research m Gilroy Festival Foods, Gilroy CA Gilroy Foods . Onion World Magazine **■ Rio Colorado Seed Company Rio Farms Seed Dynamics, Inc. Seminis Vegetable Seeds Shamrock Seed Company Snow Seed Company Sunseeds PROGRAM and ABSTRACTS p National Onion (and other Allium) Research Conference December 10-12,1998 Sacramento, California

.;. 7 WEDNESDAYDecembet 9 . ,„. 5 - 7:00 p.m. Conference Registration at the Radisson Hotel in the Hospitality Suite, Room 121

_ £5f THURSDAY,December 10 .i, ; £-- 7:00 a.m. Conference Registration and Continental Breakfast in the Conference Center - Pavilion Room f" 8:00 am. Opening, Welcome - Conference Center - Room 302

ORAL PRESENTATIONS

Session 1A: Breeding and Genetics - Conference Center - Room 302 8: IS a.m. History and pedigree of publicly-released onion germplasm in the United States during the 20th _ century - LL. Goldman and M J. Havey, Department of Horticulture, and USDA-ARS, Department of Horticulture, University of Wisconsin-Madison, Wisconsin (1) 8:45 am. Cytoplasms used commercially to produce hybrid onion - M J. Havey, USDA. ARS. Department of Horticulture, University of Wisconsin-Madison, Wisconsin (2) „ 9:00 a.m. The USDA onion breeding program: new releases and new directions - M.J. Havey, USDA, ARS, Department of Horticulture, University of Wisconsin-Madison, Wisconsin (3) 915 a.m. Onion breeding for the dehydration industry in Argentina - Claudio R. Galmarini. La Consulta. Mendoza, Argentina and Department of Horticulture, University of Wisconsin-Madison, Wisconsin (4) TO 9:30 am. Screening of for ability to produce large, mild bulbs in New York - B. L, Phillips, L. A. Ellcrbrock, and A. Pappas. Department of Fruit and Vegetable Science, Cornell University, Ithaca, New York (5)

9:45 a.m.: Break - Conference Center - Pavillion Room

Session IB: Breeding and Genetics (Continued) - Conference Center - Room 302 10: IS am. Onion breeding research at New Mexico State University - Christopher S. Cramer. Marisa M. Wall and Joe N. Corgan, Department of Agronomy and Horticulture, New Mexico State University, New Mexico (6) 1S3- 10:45 a.m. Analyses of recombinant Allium cepa x A. fisiulosum backcross individuals - Anfu Hou, Ellen B. 1 Pcfiley, Department of & Soil Science. Texas Tech University (7) 11:00 am Estimation of quantitative trait loci controlling solid content, pungency, and antiplatelet activity of onion (Allium cepa L.) - Claudio R. Galmarini, I Goldman, and M. J. Havey. USDA-ARS and Department of Horticulture, University of Wisconsin-Madison, Wisconsin (8) U:l5a.m. RFLP and FISH analysis of advanced backcrosses of in Allium interspecific hybrid (Allium cepax ) to Allium cepa - Eduardo Villanueva-Moiqueda and Michael J. Havey, USDA-ARS and frr Department of Horticulture. University of Wisconsin-Madison. Wisconsin (9) 11:30 a.m. Molecular-facilitated selection of maintainer lines in onion • All Fuai Cokce and Michael J. Havey. USDA-ARS and Department of Horticulture, University of Wisconsin-Madison, Wisconsin (10) 11:45 a.m. Transformation of onion (Allium cepa L.) - Eady C.C., R.J. Weld, and C.E. Lister, New Zealand Institute o#i for Crop and Food Research Ltd . Christchurch, New Zealand (11)

12 noon. Lynclj- Conference Center - Pavillion Room and Room 304

"^ University of California. Davu Program Page I Session 1C: Breeding and Genetics (Continued) - Conference Center - Room 302 1:00 p.m. Direct somatic organogenesis induced on mature onion ovaries or flowers - Bonn Bohanec, Zlaia Lulhar, University of Ljubljana. Biotechitical Faculty, Centre for Plant Biotechnology and Breeding, Jamnikarjeva. Slovenia (12) 1:15 p.m. Molecular analysis of cytoplasmic diversity in - Danicla Lopez Uitc and Michael J. Havcy. USDA- ARS and Department of Horticulture, University of Wisconsin-Madison, Wisconsin (13) 1:30 p.m. First report on storage longevity and genetic diversity of the USDA (A. salivum) collection - Richard llannan and Barbara Hellicr, USDA-ARS. Western Regional Plant Introduction Station, Washington State University, Pullman. Washington (14) 1:4S p.m. Genetic diversity in garlic (AIlium salivum L) as assessed by amplified fragment length polymorphism (AFLP) - Meryem Ipek and Philipp W. Simon, USDA-ARS, Vegetable Crops, Department of Horticulture, University of Wisconsin-Madison, Wisconsin (15) 2:00 p.m. Microprojectile bombardment of garlic, Allium sativum L. - J. Michele Myers and Philipp W. Simon, USDA-ARS, Vegetable Crops. Department or Horticulture, University of Wisconsin-Madison, Wisconsin (16)

Session 2: Seed Production - Conference Center - Room 302 2:15pm The effects of hybrid onion floral characteristics on honey bee activity - Bill B. Dean and Erin M. Silva, Department of Horticulture and Landscape Architecture. Washington Stale University, Prosser, Washington (17) 2:30 p.m. Onion seed production in the lower Sacramento Valley - Mike Murray and Ron Voss, Farm Advisor/County Director, University of California-Cooperative Extension. Colusa County and Vegetable Specialist. University of California. Davis (18) 2:45 p.m. Effect of harvest practices on seed quality of three onion hybrid varieties - Ron Von. Mike Murray. Kent Bradford, Herb Phillips. Jim Thompson, Vegetable Specialist, University of California-Cooperative Extension, Colusa County, Vegetable Crops Department, Agricultural and Biological Engineering Department. University of California, Davis (19)

3:00 p,m.; Break - POSTER SESSION-|r- Conference Center - Pavillion Room

Session 3A: Flavor, Human Health and Nutrition - Conference Center - Room 302 3:30 p.m A review of the regulation of sulfur metabolism and its effect on quality in onions and garlic - Jane E. Lancaster, Martin L Shaw. Meeghan D. Pilher, Julie P. Farrant and John A. McCallum. New Zealand Institute for Crop and Food Research. Chrisichurch. New Zealand (20) 3:45 p.m. Nitrogen and its interaction with sulfur will affect onion flavors • William M. Handle, Department of Horticulture, University of , Athens, Georgia (21) 4:00 p.m. Probing further into the nature of onion flavor development during storage - David E. Kopsell and William M. Randle, University of Georgia, Department of Horticulture, Athens, Georgia (22) 4:15 p.m. Juice extraction methods make difference in pungency estimation of onion - Brian K. Hamilton, Kil Sun Yoo. and Leonard M. Pike. Vegetable Improvement Center. Department of Horticultural Sciences, Texas A&M University, College Station. Texas (23) 4:30 p.m. Considerations for implementing pungency field testing and its practical implications - William M. Randle, D.E. Kopsell, DA Kopsell, Department of Horticulture. University of Georgia. Athens. Georgia (24) 4:45 p.m. Development of an automated system for pyruvic acid analysis • Kil Sun Yoo and Leonard M Pike. Vegetable Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, Texas (25) 5:00 p.tpi Adjourn

6:00 p.m. Busses leave for Banquet 6:30 • 10 p.m. Banquet • Heidrick Ag History Center, Woodland Speaker • Irwin Goldman, "From Pharaohs to Free Radicals: 5,000 Years of AJIiums and Human Well-Being"

Univcnity ofCttiTomia, Davn Program Pigc 2 FBWAY, December 11

m 7:00 a.m. Conference Registration and Continental Breakfast in the Conference Center - Pavilion Room Session 3B: Flavor, Human Health and Nutrition (Continued) - Conference Center - Room 302 m 8:00 am A Comparison of Onion-induced Platelet Aggregation by Plasma or Whole Blood Aggregometry - , K. S. Orvis. C. R. Galmarini, I. L. Goldman and M. J. Havcy, University or Wisconsin-Madison, Wisconsin (26) 8:1S a.m. The forms of selenium delivered by onions to human diet • Dean A. Kopscll and William M. Randlc, University of Georgia, Dcpamnent of Honicullurc, Athens, Georgia (27) p, 8:30 a.m. Designing the ultimate onion for human health - Leonard Pike, Kil Sun Yoo. Roger Horn, and Carmen ; Lander, Vegetable Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, Texas (28) 8:45 a.m. Opportunities to market garlic based on health outcomes: alliin, a cholesterol-lowering compound ym - S.J. Sterling and DR. Eagling. Institute for Horticultural Development (Agriculture Victoria), Victoria, Australia (29)

Session 4A: Pest Management - Conference Center - Room 302 m 9:00 a.m. Summary of white rot research presented at the 2"* Int. Symposium on Edible Alliaceae (1997, Australia), and at the 6th Int. Workshop on Allium White Rot (1998, Mexico) - Fred Crowe and Mary Ruth McDonald, Central Oregon Agr. Res. Center, Oregon Slate University. Madras Oregon and University of Guelph, Muck Crops Research Station, Kcilleby. Ontario, Canada (30) f™ 9:30 a.m. Screening onion lines for resistance to white rot (Sclerolium cepivorum) and onion maggot fly (Delia antiqua) - MHY llovius. MR McDonald, S Janse and K Vander Kooi. University of Guelph, Muck Crops Research Station, Kettlcby. Ontario. Canada (31) 9:45 a.m. An analysis of the growth and reproduction of Sclerolium cepivorum on Allium crops in relation to m traditional fungicide use and white rot incidence - Fred Crowe, Central Oregon Agr. Res. Center. Oregon State University, Madras, Oregon (32)

p_ 10:00 a.m.^J Break - Conference Center - Pavillion Room

Session 4B: Pest Management (Continued) - Conference Center - Room 302 10:30 a.m Present status of bacterial diseases of onion and their control in New York -James W. Lcrbeerand w Norman A. Gunderslicim. Department of Plant Pathology. Cornell University. Ithaca. New York (33) 10:45 a.m. Onion bacterial disease management in Colorado - Howard F. Schwartz and Kristen J. Otto. Colorado State University, Dept. or Bioagr. Sci. & Pest Mgml. Fort Collins. Colorado (34) 11 00 a.m. Evaluation of fungicides and priming of seed for the control of onion smut, Urocyslis cepulae ""* Frost, on onions - M R McDonald. S. Jansc and K Van der Kooi. Univ. of Guelph, Muck Crops Research S Station, Kctllcby, Ontario. Canada (35) 11:15 a.m. Synthetic germination stimulants decrease incidence of smut (Urocystis cepulae Frost) on onions - MR McDonald and MHY Hovius, Univ. of Guelph. Muck Crops Research Station, Keuleby, Ontario, Canada (36) m 11 30 a.m. Towards improved control of botrytis leaf blight of onion - M. A. Mutschlcr, E. D. Cobb. J. W. Lorbccr. : Dept. of Plant Breeding and Dept of Plant Pathology. Cornell University. Itliaca. New York (37) 11:45 a.m. Susceptibility of onion seed stalks and flowers to infection by Aspergillus niger Teigh - Karen L. m. Sirois and James W. Lorbcer, Department of Plant Pathology. Cornell University, Ithaca. New York (38)

12:00 n^jj^LunchrBUsiness meeting?- Main Hotel - Ballroom F

Univenity of California, Davit Progrsm Page 3 Session 4C: Pest Management (Continued) - Conference Center - Room 302 m 1:00 p.m Garlic seed clove treatments for the control of penicillium decay - R. M. Davis. B. L. Teviotdale. J. J. Nunez, and N. C. Goodcll. University of California-Cooperative Extension. Davis, Kearney Ag Center, and Kqrn County (39) 1: 15 p.m. Severe outbreak of garlic rust disease in California - S. T. Koike. R. F. Smith, R. M. Davis, J. Nunez, University of California-Cooperative Extension. Monterey County, San Bcnito County. Department of Plant Pathology, University of California, Davis. University of California-Cooperative Extension, Kern County (40) 1:30 p.m. Damage threshold for thrips on processing onions in the San Joaquin Valley, California - Richard L. Coviello and Milton E. McGiffen. Jr.. University of California Cooperative Extension. Fresno County and Dept, Botany and Plant Sciences. University of California, Riverside (41) 1:45 p.m. Evaluation of treatments for onion thrips control - Ronald F. L. Mau and Laura Gusukuma-Minuto, Department of Entomology, University of Hawaii at Manoa, Honolulu, Hawaii (42) 2:00 p.m. Evaluation of garlic extract for control of com earworm, Helicoverpa zea, in sweet corn - Benoy ** Fouche and Dawn Bninmeicr. University of California-Cooperative Extension, San Joaquin County. California (43) 2:15 p.m. Weed control with dimethenamid in onions growing on organic soils -LA, Ellerbrock and B. L Phillips. Department of Fruit and Vegetable Science, Cornell University. Ithaca, New York (44) m 2:30 p.m. The use of foliarly-applied nitrogen fertilizers for early-season weed control in onion seed crops - Mike Murray, University of California-Cooperative Extension. Colusa County (45)

- Conference Center - Pavillion Room

Session 5: Crop Culture, Physiology, Growth, Storage - Conference Center - Room 302 3:15 p.m Do onions have a critical plant size for bulb formation? - H.C. Wlen, B.S. Orenstein and L.A. Ellerbrock, Department of Fruit and Vegetable Science, Cornell University. Ithaca, New York (46) 3:30 p.m. Alternative onion transplant production in Colorado - Michael E. Bartolo and Frank C. Schweissing. Colorado Stale University. Arkansas Valley Research Center, Rocky Ford. Colorado (47) 3:45 p.m. Sudan grass rotation for improved yield and quality of onions produced on organic soils in New York - John J. Mishancc. Cornell Cooperative Extension. 1PM Program. Voorheesville. New York (48) 4:00 p.m. Non-destructive measurement of quality parameters of stored onion - Zsuzsanna F0si8s, JAzsef Fclfoldi, Sandor Istella, University of Horticulture and Food Industry, Posiharvest Department, Department of Physics and Control and Department of Vegetable Growing, Budapest (49) 4:15 p.m. Long-term storage potential of garlic {Allium salivum L) with cryopreservation and regeneration in tissue culture • Richard Hannan and Denise Garoutte, USDA. AM. Western Regional Plant Introduction Station, Washington State University, Pullman, Washington (SO) 4:30 p.m. U.S. Onion Market Dynamics - Wayne Mininger, National Onion Association 4:45 p.m. Closing Remarks

5:00 p.m. Adjourn

National Onion Research Conference Tour

7:30 a.m. Board Bus at the Radisson Hotel 8:00 -10:00 a.m. Empire Research, Davis - Continental breakfast served 10:15 - 11:00 a.m. Center for Engineering for Resistance Against Pathogens (CEPRAP) *"' 11:15- 12:00 noon Vegetable Crops Field Research Facility, University of California, Davis 12:30 p.m. Lunch at Woodland Flyers Club hosted by Seminis Vegetable Seeds 2:00-3:00 p.m. Seminis Vegetable Seeds, Woodland ^ 4:00 p.m. Arrive Radisson Hotel

Univeniiy orCatifoinia. Davit Progrun P«ge 4 POSTER SESSION I

♦ Fall-planted onion variety trials at New Mexico State University - Christopher S. Cramer, Jose Luis Mcndoza and Joe N. Corgan, Department or Agronomy and Horticulture, New Mexico Stale University, Las Cruces, New Mexico (I)

♦ Seed yield and morphology of CMS onion populations possessing the cytoplasm of A. galanthum • Michael J. Havey, USDA-ARS, Department of Horticulture, University of Wisconsin-Madison, Wisconsin (2)

♦ The Vidalia onion industry: past, present, and future - George Boyhan, University of Georgia, East Georgia Extension Center, Statesboro, Georgia (3)

♦ Onion and garlic research in India - U.S. Dalla, AS. Sidhu and S.S. Bal, Punjab Agricultural University, Punjab, India (4)

♦ Onion growth and N uptake in southeastern Colorado • Ardell D. Hulvorson, Ronald F. Foiled, and Michael E. Bartolo, USDA-ARS and Colorado Slate University, Fort Collins, Colorado (5)

♦ Irrigation scheduling to optimize yields and reduce leaching of nitrates for Maui sweet dry onions • Robin S. Shimabuku and I-Pai Wu, Hawaii Cooperative Extension Service, University of Hawaii, Kahului, and Department of Biosystcms Engineering, University of Hawaii at Manoa, Honolulu, Hawaii (6)

♦ Effects of Transplant Date and Transplant Size on Production, Quality, and Pungency of Sweet Onions • Marita Camwell. Mark Gatkcll. Xunli Nie, Richard Smith. Ben Faber. and Ron Voss. University of California-Cooperative Extension (7) ■

POSTER SESSION II

♦ Synthetic reduces viability ofSclerotium cepivontm sclerotia and incidence of white rot on onions onions - MR McDonald and MHY Hovius, Univ. of Guelph, Muck Crops Research Station, Keltleby, Ontario, Canada(8)

♦ Base temperature for garlic growth determinations in the white-garlic type - J. A. Puru-la. J L Burba and S. Lanzavechia, Garlic Project, EEA La Consulta INTA, La Consulta, Mendoza. Argentina (9)

♦ Development of a bioassay to determine the presence of specified fungal pathogens of onion - Karen L. Sirois. David P. LoParco, and James W. Lorbeer. Department of Plant Pathology. Cornell University, Ithaca, New York (10)

♦ 1PM Pest Management Guidelines for Onion and Garlic • R. Voss. R Covicllo. W. Chancy. W Bentley. S. Orloff. R.M. Davis. F. Laemmlen. C. Bell. H. Agamalian, D. Cudncy, B. Fischer. B. Westerdahl. U. Kodira, ML Flint, B. Ohlendorf. University of California-Cooperative Extension, IPM Education and Publications (11)

<9> Polymorphism in Allium species revealed by Simple Sequence Repeats - Ellen Pefliey. Anfii Hou, and Laurence Trueman, Department of Plant and Soil Science, Texas Tech University. Lubbock, TX and Horticulture Research International, Wcllsboume, Wanwick, CV (12)

Unimtily ofCtlifonii. Davis Program Page 5 Session 1 Breeding and Genetics 1998 National Onion Research Conference

History and pedigree of publicly-released onion germ plasm in the United States during the 20th century

lI L. Goldman and 2MJ. Havey 'Department of Horticulture, University of Wisconsin-Madison 2USDA, ARS, Department of Horticulture, University of Wisconsin-Madison.

Most modern onion cultivars in the U.S. descend from a few open-pollinated populations brought to this country by immigrants. For example, selection in the open-pollinated populations Common Yellow and Silverskin by onion farmers in the eastern U.S. resulted in the formation of Yellow Globe Danvers, which was a precursor to Early Yellow Globe and Mountain Danvers. These populations, along with open-pollinaled populations such as Red Wethersfleld, California Early Red, Early Grano, and Southport Red, White, and Yellow Globe formed the foundation germplasm for the first public onion breeding program, initiated in 1922 by HA Jones. Early inbreeding work by Jones and colleagues resulted in the development and widespread adoption of an inbred-hybrid breeding scheme for onion. This scheme relied on a hybrid seed production system that included genes conditioning cyioplasmic male sterility and fertility restoration. Early breeding efforts involved self-pollinating or sib-mating plants from open-pollinated populations Jones's breeding program began, the first inbred lines and hybrid cultivars from this program were released Additional state and federally supported onion breeding efforts were initiated in California, Colorado, Idaho, Iowa, Louisiana, Texas, Michigan, New Mexico, New York, Utah, and Wisconsin. Together with the US.DA. National Onion Breeding Program in Maryland, more than 60 hybrid cultivars were released from 1952 - 1998. More than 130 inbred lines, many of them sterile and maintainer pairs, were released by the public sector breeders during the same time period. This presentation will trace the history and pedigree of public onion releases and public onion breeding programs in the U.S. from the beginning of the 20th century to the present.

University of California, Davis Page 1 r

1998 National Onion Research Conference

Cytoplasms used commercially to produce hybrid-onion seed

Michael J Havey, USDA-ARS and Dep. of Horticulture 1575 Linden Dr.. University of Wisconsin, Madison, Wl 53706 Phone: 608-262-1830; Fax: 608-262-4743; Email: [email protected].

Hybrid-onion (Allium cepa) seed is produced using male-sterility systems, including asexual propagation of individual male-sterile plants and cytoplasmic-genic male sterility (CMS). The principle source of CMS used in onion seed traces back to a single plant identified in 1925 in Davis, CA. Other sources of male-sterility have been reported in Europe, Japan, and India; however, the relationships among these male-sterility systems is not clear. I undertook restriction-enzyme analyses of the organellar genomes of five independent sources of onion CMS: S cytoplasm, T cytoplasm, and sterile cytoplasms from the Japanese population Imai Wa-Se, the Dutch population Rijnsburger, and the Indian population Nasik White. The chloroplast genome of S cytoplasm and the sterile cytoplasms from Rijnsburger and Nasik White were identical for all evaluated polymorphisms; a few putative mitochondrial polymorphisms may are' being re- evaluated. Both T cytoplasm and the source of sterile cytoplasm from Imai Wa-Se appear to be closely related. These results established that the same or very similar male-sterile cytoplasms have been independently isolated.

University of California, Davis Page 2 1998 National Onion Research Conference

The USDA onion-breeding program: new releases and new directions

Michael J Havey, USDA-ARS and Dep of Horticulture 1S7S Linden Dr., University of Wisconsin, Madison, Wl S3706 Phone: 608-262-1830; Fax: 608-262-4743; Email: [email protected].

The USDA has supported onion breeding since the 1930s. The program was initially directed by Dr. Henry Jones and was located in Beltsville, Maryland. Since 1968, the USDA onion breeding program has been located in Madison, Wisconsin. For over SO years, the USDA program concentrated on the development of superior inbreds and hybrids. Our commitment to the development of superior inbreds continues, although we are spending little time on hybrid development. At the time of Dr C E Peterson's death, there were many numbered inbreds from fertile-by-fertile crosses with little to no pedigree information. Over the last 10 years, I have systematically evaluated the combining ability, disease resistance, and phenotype of all inbreds assigned numbers by the late Dr. Peterson. Almost all numbered inbreds were either poor combiners or possessed some defect. Three inbreds of merit, were given out by Dr. Peterson before his death and will be formally released. We continue to develop and evaluate inbred onion populations, concentrating on red A/B pairs, Spanish * storage crosses, and populations with low pungency and defined health benefits (in cooperation with 1. Goldman). Synthetic populations from superiorly combining inbreds have been synthesized and are being subjected to recurrent selection.

University of California, Davis Page 3 1998 National Onion Research Conference

Onion breeding for the dehydration industry in Argentina

Claudio R. Galmarini E.E.A. La Consulia INTA, C.C. 8 (5567) La Consulta, Mendoza, Argentina and Dep. of Horticulture 1575 Linden Dr., University of Wisconsin, Madison, Wl 53706 Phone: 608-262-4721; Fax: 608-262-4743; Email: [email protected]

The onion crop has great importance in Argentina and is one of the main exponed fresh vegetables. For decades there have been well established onion breeding programs, developing short, intermediate and long-day cultivars. About 2% of the Argentine onion crop is for the dehydration industry. There are 15 dehydration plants with activity concentrated in the Cuyo region. About 40% of the dehydration products are exported, mainly to Brazil. The dehydration industry uses open pollinated (OP) cultivars, mainly Southport White Globe, Ancasti, and Blanca Chaia; all have high solids and white, pungent bulbs. At the beginning of the 1990s, a special agreement between the dehydration industry and the onion-breeding program of the La Consulta Experimental Station of INTA was established. The goal is to develop OP onion cultivars and hybrids of high-solids content. In the breeding program, mass selection, recurrent selection, and hybrid production are used, together with in vitro culture techniques to propagate some bulbs of high solid content. In 1997 REFINTA 20 was released by INTA. This new cultivar originated from a selection of Southport White Globe, has white pungent bulbs, and an average total solids content of 20 ± 1%. This is 3 % more than the starting populations used by the industry (17 1 2%). The Argentine industry has exclusivity of this cultivar for 20 years and has been registered with the Argentine seed-law system. The breeding program continues to work towards the development of hybrids and evaluation of micropropagated high-solids lines.

University or California, Davis Page 4 1998 National Onion Research Conference m Screening of onions for ability to produce large, mild bulbs in New York

B L Phillips, L. A. Ellerbrock, and A. Pappas. Department of Fruit and Vegetable Science, Cornell University, Ithaca, NY 14853 ■ Phone: 607-255-6553; Fax: 607-255-0559; E-mail: [email protected]

During a period of three years, a large number of onion varieties and breeding lines were 'm evaluated for their ability to produce large(3-inch-minimum-diameter) bulbs with low pugency and high soluble solids in New York State. Additionally, the effects of soil type, drought stress, and time of harvest on bulb yield and pungency levels were measured. Pungency was assessed by analyzing for enzymatically produced pyruvic acid, and, in ** general, bulbs produced on organic soils were considerably more pungent that those produced on mineral soils Drought stress, in some case, appeared to increase onion pungency. Onion varieties that appear to offer the best potential for acceptable size, pungency levels, and storage ability in New York include Candy, RNX 10081, RNX m 10734, Viceroy, XPH 15040, Uni-Globe 108, Uni-Globe 118, and Boxster

University of California, Davis Page S 1998 National Onion Research Conference

Onion breeding research at New Mexico State University

Christopher S. Cramer, Marisa M. Wall and Joe N. Corgan Department of Agronomy and Horticulture, New Mexico State University MSC 3Q. Box 30003, Las Cruces, NM 88003-8003 Phone: 505-646-2657; Fax: 505-646-6041; E-mail: [email protected]

Over the past 20 years, the New Mexico State University Onion Breeding Program, led by Dr. Joe Corgan, has developed and released 16 open-pollinated, short- and intermediate-day onion varieties and breeding lines. The program also has investigated interspecific hybridization, pink root resistance, bolting resistance, cold hardiness, soluble solids, and pungency. Future directions of the program are release of adapted, short- and intermediate-day, open-pollinated varieties and A, B, and C lines that possess a variety of maturity dates, scale colors, soluble solids levels, and pungency levels. Lines close to release include a fall-planted, short-day, open-pollinated line with a high percentage of single centers, a fall-planted, intermediate-day, open-pollinated white line, a spring-planted, late-maturing, open-pollinated white line, and spring-planted, yellow A- B lines. Future research will be directed towards identifying genes associated with pink root and Fusarium basal rot resistance, and further understanding of bolting, cold hardiness, bulb quality traits, soluble solids, and pungency.

University or California, Davis Page 6 1998 National Onion Research Conference

Analyses of recombinant AUium cepa x A. fistulosum backcross individuals

Anfu Hou, Ellen B Peffley Texas Tech University, Department of Plant & Soil Science Phone: 80-742-2637; Email: [email protected]

Interspecific hybridization has been used for the purpose of introducing desirable traits from AUium fistulosum into A. cepa, however, onion cultivars possessing A. fistulosum genes have not been released. A major barrier for successful introgression has been sterility of Fi hybrids and derivatives. F|BC3 plants in this study were generated by backcrossing A. cepa to A. cepa x A. fistulosum hybrids. Characters evaluated to track introgression were bulb, foliage, and inflorescence morphology; isozymes, chromosome karyotypes, and fluorescence in situ hybridization patterns. Overall, growth habit and floral characters of the F1BC3 plants were much like A. cepa. Soluble solids and pungency in FiBCj bulbs ranged from low as in A. cepa to high as in A. fistulosum. Bulb- type but recombinant onions with high soluble solids and low pungency were identified. Fertile, A. cepa -like plants were recovered which had high pollen viability, set seeds, and possessed A. fistulosum isozymes. Fluorescence in situ hybridization was done with biotin-labeled genomic DNAs of both species. A highly repetitive 376 bp A. fistulosum DNA sequence revealed telomeric hybridization sites; similar telomeric sites were observed when hybridizing labeled A. fistulosum genomic DNA onto chromosomes of A. fistulosum individuals and F|BCj plants.

University of California, Davis Page 7 1998 National Onion Research Conference

! Estimation of quantitative trait loci controlling solid content, pungency, and antiplatclet activity of onion (Allium cepa L.) m Claudio R. Galmarini, I. Goldman, and M. J. Havey USDA-ARS and Dep. of Horticulture 1575 Linden Dr., University of Wisconsin, Madison, WI 53706 ^ Phone; 608-262-1830; Fax: 608-262-4743 1 Email: [email protected] and [email protected]

A 138-point genetic map is being used to identify and estimate the magnitude of P quantitative trait loci controlling, solids content, pungency, and antiplatelet activity of onion. Solid content is an important characteristic related to onion flavor, texture, and storability and has practical importance for the dehydration industry. The antiplatelet activity of onion may be beneficial to the human cardiovascular system. Pungency is an m important quality trail for fresh consumption. Significant correlations have been demonstrated between enzymatically produced pyruvic acid and sensory evaluations of onion pungency. QTL controlling pungency, total solids, soluble solids, and antiplatelet m activity are being estimated over environments using 54 F3 families, derived from the cross between Brigham Yellow Globe 15-23 (BYGI5-23) and Alisa Craig (AC43). Maturity (days after planting to 50% collapsed foliage), storability, soluble solids, total solids, pungency and antiplatelet activity are evaluated. This study should determine if m correlated traits are conditioned by the same chromosome regions and, over the long term, if marker-facilitated selection can be used to develop value-added onion cultivars.

University of California, Davis Page 8 1W8 National Onion Research Conference

RFLP and FISII analysis of advanced backcrosses of an Allium interspecific hybrid {Allium cepa X Allium fistulosum) to Allium cepa m Eduardo Villanueva-Mosqueda and Michael J. Havey USDA-ARS and Dep. of Horticulture 1575 Linden Dr, University of Wisconsin, Madison, WI 53706 m, Phone: 608-262-1830; Fax: 608-262-4743; Email: [email protected].

Onion (Allium cepa L.) is the most important species of the cultivated . Breeders have attempted to incorporate quality and resistance traits from Allium fistulosum into the pi onion genome. Although there are several reports of successful interspecific hybridizations between A. cepa and A. fisiulosum, there has not been strong evidence of recombination among the genomes. After more than 50 years of interspecific hybridizations and backcrossing to onion, no successful introgression has been *** convincingly documented The objective of this study was to use FISH and RFLPs to assess recombination between the genomes of A. cepa and A. fistulosum using BC progenies in the normal male-fertile cytoplasm of A. cepa. Sequence divergence between A. cepa and A. fisiulosum was sufficient to allow chromosomes to be distinguished by GISH and revealed evidence for recombination among the genomes of A. cepa and A. fistulosum. RFLP analysis demonstrated that advanced backcross populations possess the normal male-fertile cytoplasm and the 45s ribosomal DNA of bulb onion.

University of California, Davis Page 9 1998 National Onion Research Conference

Molecular-facilitated selection of maintainer lines in onion

Ali Fuat Gokce and Michael J. Havey USDA-ARS and Dep. of Horticulture 1575 Linden Dr., University of Wisconsin, Madison, Wl 53706 Phone: 608-262-1830; Fax: 608-262-4743; Email: [email protected].

Cytoplasmic-genic male sterility (CMS) is used to produce hybrid-onion seed. For the most widely used source of CMS in onion, male sterility is conditioned by the interaction of sterile (S) cytoplasm and the homozygous recessive genotype at a single nuclear male- fertility restoration locus (Ms). Maintainer lines used to seed propagate male-sterile lines possess normal fertile (N) cytoplasm and the homozyous recessive genotype at the Ms locus. Presently, it takes four to eight years to establish if maintainer lines can be extracted from an uncharacterized population or family. We previously developed a PCR marker useful to distinguish N and S cytoplasms of onion. To tag the nuclear male- fertility restoration locus (Ms), we evaluated segregation at Ms over at least three environments. Segregations of AFLPs, RAPDs, and RFLPs revealed molecular markers flanking the Ms locus at 1.9 and 7.1 cM. These organellar and nuclear markers are being used to select plants from open-pollinated onion populations and determine the reduction in testcrosses required to identify CMS-maintaining genotypes.

University of California, Davis Pa8e l'J98 National Onion Research Conference

Transformation of onion (Allium cepa L.)

Eady C.C, Weld R.J. and Lister C.E. New Zealand Institute for Crop and Food Research Ltd. Private Bag 4704, Christchurch, New Zealand Phone: 64-3-32S-6400; Fax: 64-3-325-2074; Email: eadydgcropxrUz

An Agrobacterium tumefaciens - mediated transformation method has been developed for onions (Allium cepa L.) Transgenic plants have been produced at a maximum transformation frequency from immature embryos of 3.2 %. The method takes between 3-5 months from explant to primary regenerant entering the glasshouse. Multiple shoot formation from primary transgenic material made possible the clonal multiplication of these transformants. The T-DNA transferred to the plants contained the m-gfpS-ER reporter gene and the nplll antibiotic resistance gene. Onion tissue expressing the m-gfp5- ER gene was observed to fluoresce green when excited with blue light. Expression of nptll in onion plants has conferred the ability to root ori medium containing high levels of the antibiotic geneticin. The transgenic nature of individual plants was confirmed by Southern blot analysis. Over 50 transgenic plants, from 14 independent transformation events, have been produced in three experiments. We believe this to be the first routine onion transformation protocol.

University of California, Davis Pa6c ' 1 1998 National Onion Research Conference

Direct somatic orgnnogenesis induced on mature onion ovaries or flowers

Borut Bohanec, Zlata Luthar University of Ljubljana, Biotechnical Faculty, Centre for Plant Biotechnology and Breeding, Jamnikarjeva 101, 1000 Ljubljana, Slovenia. Phone: 386-61-123-11-61; email: [email protected]

Despite several attempts a repeatable genetic transformation procedure was not yet reported in onion. In most species, usually a key factor needed for a successful transformation protocol was the establishment of a tissue culture protocol producing high frequency regeneration via organogenesis or embryogenesis. Such regeneration procedure would be also appropriate for micropropagation especially if callus formation can be excluded. During last two years in our laboratory a series of experiments were conducted to assess optimal in vitro protocols needed to achieve direct somatic organogenesis in onion. Studies, focused on a two step induction/regeneration procedure included variation in choice of organs, duration of induction period, choice or plant growth regulators used in both stages, macro and micro elements mixtures, content and choice of carbohydrates, gelling agents, light conditions, organ extraction protocols and effects of genotypes. As result of these studies a highly repeatable protocol was optimized resulting in a high frequency induction of direct somatic organogenesis. Complete flower buds and especially isolated ovaries were found highly responsive producing organogenic (embryogenic) structures without any callus formation. Such organogenic structures (at this stage ideal for transformation events) later form multiple shoots, which can be grown to adult plants via standard micropropagation procedures. At present, protocols are available for an efficient micropropagation procedure resulting with several thousand of clones per donor plant, while transformation protocols, using biolistic and Agrobaciehum approach is in process.

University of California. Davis Page 12 I-198 National Onion Research Conference

Molecular analysis of cytoplasmic diversity in leek

Daniela Lopez Leite and Michael J. Havey USDA-ARS and Dep. of Horticulture 1575 Linden Dr, University of Wisconsin, Madison, WI 53706 Phone: 608-262-1830; Fax: 608-262-4743; Email: [email protected]

Hybrid leek (Allium ampeloprasum L. war.-porrum) is more uniform and higher yielding than open-pollinated cultivars. Leek has perfect flowers and a male-sterility system is required to produce hybrid seed. A genie male-sterile plant has been identified and asexually propagated as the female parent of leek hybrids. A system of cytoplasmic male sterility (CMS) in leek would be a cheaper alternative to the high cost of asexually propagating female plants for hybrid production. CMS systems are used to produce hybrid bulb onion, bunching onion, and chive, but no CMS system has been identified in leek. Restriction fragment length polymorphisms (RFLPs) in the chloroplast and mitochondrial genome have correlated with CMS in many crops. We undertook gel-blot analyses of the chloroplast and mitochondrial DNAs to identify polymorphisms among the organellar genomes of 60 accessions of cultivated A. ampeloprasum No polymorphisms were detected in the chloroplast genome of leek and kurrat Three accessions of leek and one of kurrat possessed polymorphisms for seven mitochondrial probe-enzyme combinations. Great-headed garlic differed from leek and kurrat for six polymorphisms in the chloroplast genome and for many mitochondrial probe-enzyme combinations. We identified individual leek plants possessing mitochondrial polymorphisms and are presently establishing if polymorphic cytoplasms correlate with the expression of CMS.

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University or California. Davis Page 13 1998 National Onion Research Conference

First report on storage longevity and genetic, diversity of the USDA garlic (A. sativum) collection

Richard Hannan and Barbara Hellier USDA, ARS, Western Regional Plant Introduction Station 59 Johnson Hall, WSU, Pullman, WA m> Phone: 509-335-1502; Fax: 509-335-6654; E-mail: [email protected]

The USDA, ARS, NPGS maintains the garlic collection at the Western Regional Plant Introduction Station, Pullman, WA. The collection currently numbers 213 accessions. m The garlic germplasm is grown each year in field plots in order to provide material for regeneration and for distribution. Following harvest, curing and cleaning, the garlic is stored at 13-15T and 55% RH as intact bulbs. A common interest and concern with garlic is the longevity of each clone in storage. A study on 177 accessions was conducted I to detennine how long each accession could be maintained under our storage conditions. Three representative bulbs per accession were selected and numbered. Readings were taken on bulb firmness (scale 1-5 where l=soft and 5=vcry firm) and sprouting (visible shoots=sprouted) every 30 days for 12 months. The accessions were considered culls when they had sprouted and/or turned soft (firmness<3). Results indicated a wide range of diversity in the storage life of the PI garlic germplasm. Some genotypes sprouted as early as 90 days after harvest, while others remained dormant and firm for over 12 rm months. Approximately half of the accessions had sprouted by the end of March. After that, those that had not sprouted, slowly desiccated. After 12 months in storage 8% of the accessions were still firm, not sprouted and not desiccated

University of California, Davis Page 14 I9'J8 National Onion Research Conference

Genetic diversity in garlic (Allium sativum L.) as assessed by amplifled fragment length polymorphism (AFLP) m Meryem Ipek & Philipp W. Simon USDA-Agricultural Research Service, Vegetable Crops, University of Wisconsin Department of Horticulture, 1575 Linden Drive, Madison, WI 53706 m Phone: 608-262-1248; Fax: 608-262-4743; m Email: [email protected] [email protected]

Garlic (Allium salivum L), an asexually propagated crop known for at least 5000 years, wn displays great morphological diversity. The genetic diversity of 53 garlic clones and three A longicuspis clones, the proposed progenitor of A. salivum, was evaluated using AFLP. Three primer combinations of EcoR I + 4 - Mse I + 3 (where + 4 and + 3 are the number of selective bases used for the corresponding primer) generated a total of 183 m polymorphic fragments. The Jaccard's similarity matrix was used for UPGMA cluster and principle component analyses. The results of cluster analysis were compared with morphological characters and isozyme groupings of Pooler and Simon (1993). Although similarities between the clusters were low (( 0.30), some clones within the clusters were •pn very similar (0.95). Furthermore, 18 clones represented only six different types, within which they shared 100% polymorphic AFLPs. These may, therefore, be duplicates. In agreement with the results of other investigators, A. longicuspis and A. sativum clones were clustered together with no clear separation, suggesting these species are not genetically distinct. Since AFLPs are abundant, this technique can be another tool for detailed assessment of genetic relationships in garlic.

University of California, Davis Page 15 1998 National Onion Research Conference

Microprojectile bombardment of garlic, Allium sativum L.

J Michele Myers and Philipp W Simon m USDA-Agricultural Research Service, Vegetable Crops, University of Wisconsin, Department of Horticulture, 1575 Linden Drive, Madison, WI 53706 Phone: 608-262-1248, Fax: 608-262-4743; E-mail: [email protected]

We have successfully transferred and expressed the reporter gene p-glucuronidase (GUS) and the selectable marker neomycin phosphotransferase (NPT II) gene into the garlic, Allium sativum L. The clone 'RAL27' was transformed using microprojectile m bombardment as the method of gene delivery. Cell suspensions derived from callus produced on root tissue were bombarded with 1.6 micron gold particles coated with pBI121. The GUS gene was under the control of the CaMV35S promoter white the NPT II gene was under the control of the nopaline synthase promoter (nos). GUS assays were "" performed 2 days post bombardment to confirm positive initial transformation events. Selection of putative transformants occurred on medium supplemented with parmomycin sulfate (100 mg L1) and solidified with 0.35% low gelling temperature agarose. After 14 to 16 weeks on selection medium, regenerated shoots were observed on several calli. m Incorporation of foreign genes into the genome of sixteen-month-old transgenic plants was confirmed by PCR with specific primers for GUS and NPT II and Southern blot analysis. GUS assays of sixteen-month-old confirmed transformed plants revealed no m GUS activity.

University of California, Davis Page 16 Session 2 Seed Production 'J'Jg National Onion Research Conference

The effects of hybrid onion floral characteristics on honey bee activity

Bill B. Dean and Erin M. Silva p* Washington State University, Department of Horticulture and Landscape Architecture 24106 N. Bunn Rd, Prosser, WA 99350 Phone; (509) 786-9260; FAX: (509) 786-9370; email: silva(g!wsunix-wsu.edu

Poor hybrid onion seed yields due to lack of pollination by the honey bee continues to be a major problem in Washington's Columbia Basin region. This study examined onion floral characteristics and honey bee activity. Nine, hybrid onion parents differing in m relative bee attractiveness were grown in replicated 2.4m X 4-9m field plots. Nectar samples were collected from the flowers to determine total nectar volume, sugar concentration, and sugar quantity. Volatile floral odor samples were collected using headspace analysis techniques and analyzed by GC/NIS to determine qualitative and !"" quantitative differences in odor profiles and their effect on bee attractiveness. Hybrid i onion fields in Washington, Oregon, and Idaho also were analyzed to determine the effects on nectar production, odor production, and competitive crops on relative bee activity and final seed yield. Variation was observed in nectar production and odor rwi production between the more and less attractive hybrid parents. When presented with an alternative crop, honey bees ignored the onion seed crop in favor of other food sources. Onion floral volatiles were found to be composed of predominantly sulfur compounds, with the more, attractive hybrid parents emitting a greater quantity of total volatiles.

University of California, Davis Page 17 1998 National Onion Research Conference

Onion seed production in the lower Sacramento Valley

Ron Voss1 and Mike Murray2 University of California 'Vegetable Crops Department One Shields Avenue, Davis, C A 95616 Phone: 530-752-1249; Fax: 530-752-9659; E-mail: [email protected] 2Colusa County CE, P.O. Box 180, Colusa, CA 95932 Phone: 530-458-0577; Fax: 530-459-4625; E-mail: [email protected]

Limited acreages of direct-seeded onion seed crops have been grown in the lower Sacramento Valley for many years. Recently, the acreage of commercial hybrid seed production has expanded The crops are planted from August through September and harvested the following July through August. Important production challenges include weed and disease management. The crop is hand-harvested, dried on tarps exposed to the sun and threshed in the field before delivery to the seed contractor. This presentation will identify and discuss the major production and harvest issues encountered in the region.

University of California, Davis Page 18 1998 National Onion Research Conference

Effect of harvest practices on seed quality of three onion hybrid varieties Ron Voss1, Mike Murray2, Kent Bradford1, Herb Phillips1, Jim Thompson3 University of California 'Vegetable Crops Department, and Agricultural and 'Biological Engineering Department One Shields Avenue, Davis, CA 95616 2Colusa County CE, P.O. Box 180, Colusa, CA 95932 Phone: 530-752-1249; Fax: 530-752-9659; E-mail: [email protected]

The Sacramento Valley is an important seed production area for intermediate and long day hybrid onion cultivars. Onion seed stalks and are typically harvested by hand in mid-summer, air-dried in the sun on canvas tarps, and threshed, before delivery to the contracting seed company. Some cultivars have borderline, or below, acceptable germination (e.g. 85%) The objective was to determine how seed quality (e.g. germination, vigor, size/weight) can be affected by harvest related practices. An experiment was conducted with variable harvest (i.e. cutting) dates, forced vs. air drying, and sun exposed vs. shading. Samples were also collected at various locations in the harvest process and in the drying piles. Temperature within the piles was monitored. Three cultivars were used - Linda Vista, Cougar and Mercedes. Hand and machine threshed samples were collected. Standard germination/vigor tests were conducted by California Crop Improvement Association. The results of the trial will be discussed and recommendations for further research or changes in practices will be presented.

University of California, Davis Page 19 Session 3 Flavor, Human Health and Nutrition 1998 National Onion Research Conference

A review of the regulation of sulfur metabolism and its effect on quality in onions and garlic

Jane E. Lancaster, Martin L. Shaw, Meeghan D. Pither, Julie P. Farrant and John A. McCallum New Zealand Institute for Crop and Food Research Private Bag 4704, Christchurch New Zealand Phone: 643-325-6400; Fax: 643-325-2074; Email: lancasterjVScrop.cri.nz

A distinguishing feature of the 500 or so Allium species is the metabolic network of sulfur compounds resulting from the high sulfur content in these species. Sulfur nutrition affects the flavor quality of onions and garlic and has been shown to affect the storage quality of onions. Recent literature on the uptake, reduction and assimilation of sulfur will be discussed particularly in relation to differences in sulfur metabolism between onions and garlic. The effect of sulfur nutrition on the expression of the flavor enzyme alliinase will be discussed. It is concluded that sulfur uptake from a given medium is similar for both onion and garlic but differences in metabolism within the plants lead to differences in quality characteristics.

University of California, Davis Page 20 1998 Nalional Onion Research Conference

Nitrogen and its interaction with sulfur will affect onion flavors

William M. Randle Department of Horticulture, University of Georgia, Athens, GA 30602-7273

While much of our previous work focused on the effect of sulfur (S) and flavor development, empirical observations of field-grown onions hinted that the level of applied nitrogen (N) could affect flavor intensity. In response, we conducted a series of experiments to: 1) determine the effect of increasing N levels on onion flavors and, 2) determine the interaction of N and S levels on onion flavors. Each experiment was conducted in the greenhouse using nutrient solutions. Increasing N availability increased bulb pungency except the highest N level. Total flavor precursor content (ACSO) increased as N increased, but the ratio of the individual precursors changed. High N favored methyl cysteine sulfoxide and propyl cysteine sulfoxide accumulation, but decreased l-propenyl cysteine sulfoxide. Bulb firmness decreased as N increased. There was a significant interaction of N and S fertility on bulb pungency and ACSO content. When N levels were very low, bulb pungency was high regardless of the S level. With high S, increasing N generally decreased pungency. Increasing S increased ACSO content at all N levels. Increasing N generally increased ACSO content at all S levels. Therefore, N and S fertility need to be considered when growing onions for flavor intensities.

University of California, Davis Page 21 1998 National Onion Research Conference

Probing further into the nature of onion flavor development during storage

David E. Kopsell and William M Randle University Of Georgia, Department Of Horticulture, 1111 Plant Sciences Building Athens, GA 30602 Phone: 706-542-2471, Fax: 706-542-0624; E-mail: davekops@archev uga.edu

In previously reported studies, the enzymatically formed pyrulvic acid (EPY) and S- alk(en)yl cysteine sulfoxide (ACSO) levels were examined during cold temperature storage. In these experiments, ACSO changes during storage could not explain EPY behavior. Investigation has been conducted into the enzymatic reaction components in order to understand how onion flavor is changing. Three SD cultivars were greenhouse grown in artificial media and stored under two separate conditions, 3°C, 70% RH and ambient room temperature (RT). Experimental data was taken on EFY, ACSO levels, cellular pH, thiosulfinale, production, alliinase activity, alliinase time-course hydrolysis of ACSOS, and bulb dormancy characteristics. EPY for 'Granex 33' and 'Dehydrator #3' followed previously reported trends, while 'Evita' EPY increased slightly. The umoles/ml (Z.E)-propanethiol S-oxide, the lachrymatory factor (LF), for 'Granex 33' and 'Evita1 increased, while the LF for 'Dehydrator #3" decreased. EPY for RT storage was lower than cold storage for the cultivars. Background cellular pH increased for each cultivar during cold storage and was higher than RT pH. Onion flavor development during storage is much more complex that previously thought, requiring the use of many combined analyses to fully explain.

University of California, Davis Page 22 IW8 Nalional Onion Research Conference

Juice extraction methods make difference in pungency estimation of onion

Brian K Hamilton, Kil Sun Yoo, and Leonard M. Pike Vegetable Improvement Center, Department of Horticultural Sciences Texas A&M University, College Station, TX 77843 Phone: 409-862-4951; Fax: 409-862-4522, E-mail: [email protected]

Onion pungency has been widely estimated by measuring pyruvic acid content in extracted onion juice. The original method by Schwimmer and Weston (SW) used diluted juice from homogenated onion tissue with water. The SW method was slow and several modifications were developed to speed up sample preparation time, such as extracting juice by pressing, maceration of tissue in a plastic bag, or homogenization of tissue without water. We compared these four methods and found considerable difference in the pyruvic acid content due to how the samples were processed. Since every analysis laboratory adopts a different extraction method and this may cause varying results of pungency estimation, we would like to suggest that a common method be established for measuring onion pungency throughout the industry.

University of California, Davis Page 23 1998 National Onion Research Conference

Considerations for implementing pungency field testing and its practical implications

William M. Randle, D.E. Kopscll, DA. Kopsell Department of Horticulture, University of Georgia, Athens, GA 30602-7273

Onions can be marketed for specific purposes; some are intended to be eaten raw, others are intended for cooking, while others may be used in the dehydrated state. However, onion flavor intensity can vary dramatically within these categories. To better inform consumers of the flavor intensity they might be purchasing, field sampling and pungency testing can be used. Initiating a successful testing program requires several procedures to be implemented. First, a valid pungency testing method must be used which represents established sensory experiences with the chemical analysis. Second, because flavor gradients exist within the bulb, tissue taken for analysis must represent the overall bulb pungency. And third, a statistically valid sampling procedure must be ascertained for production areas based on environmental conditions and varietal usage. If a field is properly tested, a pungency mean and standard deviation can be determined. These values can then be used to place onions in pungency categories, and the consumer will be better informed. At the farm level, pungency patterns can be determined by coupling field sampling with global position satellite systems. Precision farming techniques can be then be employed to improve flavor quality and consistency.

University of California, Davis Page 24 1998 National Onion Research Conference

Development of an automated system for pyruvic acid analysis

Kit Sun Yoo and Leonard M. Pike Vegetable Improvement Center, Department of Horticultural Sciences Texas A&M University, College Station, TX 77843

An automated system for pyruvic acid analysis was developed in order to screen a large number of onion bulbs in our breeding program. The system includes two HPLC pumps, an autosampler with a S micro liter loop, a column heater set to 70°C, a spectrophotometric detector set to 485 nm, and an integrator or data collection computer. Each pump delivers 0.7 ml dinitro phenyl hydrazine (DNPH) or 1.4 ml NaOH per minute. Micro filtered onion juice is injected by an autosampler, mixed with DNPH solution, and reacted in the column heater. The NaOH solution is mixed at the end of the heater and absorbency at 485 nm was measured. Peak area of each sample was calculated into amount of pyruvic acid by using a standard curve. This new method can eliminate human error, has high repeatability, and can run a sample per minute

University of California, Davis Page 25 I : 1998 National Onion Research Conference

A comparison of onion-induced platelet aggregation by plasma and wholeblood aggregometry

K. S. Orvis, C. R. Galmarini, I. L. Goldman and M. J. Havey University of Wisconsin-Madison, 1575 Linden Dr., Madison, Wl 53706. Fax: 608-2624743; Email: [email protected] or [email protected]

Onions posess a unique in vitro antiplatelet effect. This property has been implicated in the prevention of cardiovascular disease, the leading cause of death in the United States today. Previous investigation of this trait in onion has been by plasma aggregometry. In this method, platelet rich plasma is isolated from human volunteers and mixed with onion extract and platelet agonist. An alternative method that is quicker, less complicated and may have more biological relevance, measures platelet aggregation in whole blood. A set of experiments was conducted to compare onion-induced aggregation in both plasma and whole blood. Two agonists, ADP and collagen, as well as several different onion germplasm accessions were compared in replicated trials in both systems. In these experiments, ADP proved to be more effective than collagen in plasma aggregometry, while collagen was more potent than ADP in whole blood aggregometry. Preliminary data indicate a positive correlation between the two systems. Ranking of antiplatelet activity strength across germplasm accessions was preserved across systems. Data demonstrate that future investigation of onion-induced antiplatelet activity may utilize whole blood aggregometry, a reliable, quick technique applicable to a breeding program.

University of California, Davis Page 26 I 'J98 National Onion Research Conference

The forms of selenium delivered by onions to human diets

^ Dean A. Kopsell and William M. Randle University of Georgia, Department of Horticulture, 1111 Plant Sciences Building Athens, GA 30602 Phone: 706-542-2471; Fax: 706-542-0624; E-mail: [email protected]

Selenium has long been established as an essential trace element in mammalian health. Research has shown both Se deficiency and toxicity to be very real concerns. The health benefits of immune system enhancement, cancer suppression, and cardiovascular disease M reduction are all associated with increased dietary Se. Because of its unique metabolism, the form of Se ingested becomes vital to its medicinal attributes. Onions and garlic were revealed to be excellent delivery sources of organic forms of Se in human diets. fOT, Selenium can exist in plants as seleno-proteins, seleno-amino acids, or as inorganic Se. The form of Se ingested will determine if it is metabolized safely, or accumulated to potentially harmful levels Onion tissues grown in the presence of selenate were found to contain mostly water-soluble forms of Se. Protein and amino acid fractions made up m significant portions of the water-extractable Se. The level of Se in lipid fractions was minimal. Levels of insoluble, or tightly held Se were also identified. The form of Se delivered by plants is much more effective than traditional Se supplementation. If Allium species are used to deliver Se to human diets knowledge of the form of Se existing in the i™* plant is vital to its application as a beneficial source of Se.

University of California, Davis Page 27 1998 National Onion Research Conference

Designing the ultimate onion for human health

Leonard Pike, Kil Sun Yoo, Roger Horn, and Carmen Lander

In the early days of mankind, the first humans relied on food plants to provide their very existence. They soon found that certain plants had medicinal properties and consumed them to prevent and cure illness. As medical technology advanced, physicians began treating diseases with drugs and surgery. Within the last ten years, the philosophy of preventing disease is returning to choosing health giving foods especially vegetables and fruits. Until recently there has been limited emphasis placed on improving health benefits offered by some vegetables. This has been attempted by breeding for increased levels of certain compounds that were identified as being important to good health, such as quercetin in onions Garlic, onions, and peppers have long been thought of as healthful foods and are considered to have properties that can prevent various diseases. More recently cabbage, broccoli, cauliflower (and other cruciferous crops), potatoes, melons and cucumbers have been listed by medical scientists as having possible effects against cancer. Medical scientists are now aggressively exploring plant chemistry to determine which natural occurring compounds provide specific protection against diseases such as cancer, heart disease, diabetes, and others diseases. These research efforts provide plant breeders with credible information to justify developing new cultivars with uniform, higher levels of the health-providing compounds. One of the top priorities the Vegetable Improvement Center is to work with medical scientist at M.D. Anderson Cancer Center and Baylor College of Dentistry. Considering documented results from these two prestigious institutions, plant breeders at Texas A&M University have established vegetable breeding programs to develop designer vegetables for improved health. At present, we have set specific objectives to improve onions, for flavor, appearance and to contain uniform high levels of certain aniioxidants and other phytochemicals that offer protection against various human diseases. Emphases on onions include work on organo-sulfur compounds and quercetin.

University of California, Davis Page 28 1998 National Onion Research Conference

Opportunities to market garlic based on health outcomes: alliin, a cholesterol-lowering compound m Sterling, S.J andEagling, DR. Institute for Horticultural Development (Agriculture Victoria) 621 Burwood Hwy. Knoxfield, Victoria 3176 Australia ^ Phone:+61 3 9210 9222 Fax: +61 3 9800 3521 [email protected] i"t Alliin, the main cysteine sulfoxide found in garlic, is similar in structure to the cysteine sulfoxides in onions. Like quercetin (a flavonol found in onions), alliin has been shown to have a range of medical benefits including the reduction of blood cholesterol, and for this reason, alliin is of interest to the pharmaceutical industry. Research was conducted ""* at sites along the eastern seaboard of Australia and results showed that garlic grown in this area contains levels of alliin up to 20 mg/g by fresh weight, the highest level so far recorded world-wide. Further trials have shown that it is possible to consistently achieve the level of alliin required for pharmaceutical processing (4 Smg/g FW or higher) over a wide range of Australian climates, dependent on varietal needs.

University of California, Davis Page 29 Session 4 Pest Management 1998 National Onion Research Conference

Summary of white rot research presented at the 2 Int. Symposium on Edible Alliaceae (1997, Australia), and at the 6th Int. Workshop on Allium White Rot (1998, Mexico)

Fred Crowe Central Oregon Agr. Res. Center, Oregon State University m 850 NW Dogwood Ln., Madras OR 97741. Phone: 541-475-7107; Fax: 541-475-6390; E-mail: [email protected]

Mary Ruth McDonald rm University of Guelph, Muck Crops Research Station 1125 Woodchoppers Ln., RR01., Kettleby, Ontario LOG I JO Phone: 905-775-3783; Fax: 905-775-4546; E-mail: [email protected]

F*1 White rot disease of Alliums, incited by Sclerotium cepivorum, permanently infests field soil. Traditional means of disease control have proven insufficient in cool season production where environment favors activity of S. cepivomm As a result, white rot already has greatly reduced or now threatens sustained commercial production of Allium fa™1 crops in many parts of the world. White rot research has been and continues to be well distributed worldwide, with limited contact among researchers in many countries. A summary of research reports from two recent international conferences will be presented. ^ While white rot remains difficult to control with single methods, many who work with this disease now believe control may be possible with integrated methods.

University of California, Davis Page 30 1998 National Onion Research Conference

Screening onion lines for resistance to white rot (Sclerotium cepivorum) and onion maggot fly (Delia antiqua).

Hovius MHY, MR McDonald, S Janse and K Vander Kooi Muck Crops Research Station, University for Guelph, 1125 Woodchoppers Lane, Kettleby, ON, LOG 1J0 rm Phone: 905-775-3783; Fax: 905-775-4546; E-mail: mhoviustgiuoguelph ca

White rot of onions, a threat to the onion industry world wide, is a major limiting factor in the production of onions in the Holland Marsh and surrounding areas in Ontario, mi Canada. Resistance to registered insecticides has created a.need for new control methods for the onion maggot fly. White rot, caused by Sclerotium cepivorum and the onion maggot (Delia antiqua) are specific pests only of Allium species. Work by Esler and Coley-Smith (1983) suggested that the mechanism which initiates the germination of m white rot sclerotia is linked to onion thiols and phenols and that those same chemicals attract onion maggot flies to the plants. Gabelman (1991) also suggested that there may be a positive relationship between white rot incidence and maggot fly damage in onions. m Onion breeding lines obtained from Dr. 1. Goldman, University of Wisconsin, Dr Rob Maxwell, Petoseed, Payette, Idaho and Asgrow Ltd in 1996 and 1997 were evaluated for white rot resistance in infected commercial field sites. Onions were assessed for visible white rot incidence at harvest maturity. Seeded and transplant trials were conducted to rm evaluate plant resistance to onion maggot at the Muck Crops Research Station where onion maggot flies occurred naturally. Maggot fly damage assessments began one week after the peaks of the 1* and 2nd generations and at harvest. In 1996 and 1997 significant (P=0.05) differences in white rot incidence among breeding lines were found. Significant w differences in onion maggot damage and yield were found among the onion lines in both years. Significant (P=005) and positive Pearson and Spearman Rank correlations (r=0 55 to 0.71) were found between white rot incidence and maggot fly damage assessments at different intervals during the growing season. Total maggot fly damage I was correlated (Pearson) with white rot incidence at 2 out of 3 sites in I99S only In 1996, a significant but negative Pearson correlation (r=0.49) was found between white rot incidence and maggot fly damage at harvest. Though we were unable to identify a m consistent link between resistance to onion white rot and resistance to the onion maggot fly, the results from the Pearson correlation suggest that a tenuous relationship may exist. This relationship requires further investigation. mi References

I. Ester G and JR. Coley-Smith, 1983 Flavour and odour characteristics of species of Allium in na* relation to their capacity to stimulate germination of sclerotia of Sclerotium cepivorum. Plant Pathology. 32:13-22.

™, 2. Gabelman WH. 1991 White rot and onion maggot. Proceedings of the National Onion Research Conference., Savannah, GA: 147-151.

University of California, Davis Page 31 National Onion Research Conference

An analysis of the growth and reproduction of Sclerotium cepivorum on Alliunt crops in relation to traditional fungicide use and white rot incidence

Fred Crowe Central Oregon Agr Res. Center Oregon State University, 8S0 NW Dogwood Ln , Madras OR Phone: 541 -475-7107; Fax 541 -475-6390; E-mail fred.crowefjBorst edu

Essentially all sclerotia of S. cepivorum eventually germinate in the presence of onion and garlic roots in cool soils. Reproduction in roots is slight. Thus, nearly all sclerotia present after an incidence of white rot are newly formed on decayed bulbs. Fungicides, traditionally applied as seed treatments or in-furrow treatments at planting time, can directly reduce the current season incidence of white rot, but frequently fail to reduce the post-harvest inoculum density compared to the pre-plant inoculum density Theoretically, superior fungicides which suppress bulb infection season long would greatly reduce resultant inoculum density, and their continued use could achieve near- eradication of sclerotia. However, fungicides which fail to suppress bulb infection season long may result in increased inoculum density, with even poorer control in subsequent crops. This is because S. cepivorum continues to spread up and down the planted row on root systems below the zone of traditional fungicide application. If fungicides degrade prior to harvest, S. cepivorum then moves up the now-unprotected roots to decay bulbs at a later stage of bulb development, when the food base for fungal reproduction is greatest. Traditionally-applied fungicides, then, must be very effective against S. cepivorum, they must last for the full season, and they must do so dependably. Deeper placement of less- than-superior fungicides through the zone where root density is highest should reduce plant-to-plant spread, late season plant loss and late season fungal reproduction.

University of California, Davis Page 32 1998 National Onion Research Conference

Present status of bacterial diseases of onion and their control in New York

James W. Lorbeer and Norman A. Gundersheim Department of Plant Pathology Cornell University f« Ithaca, NY 14853 Phone: 607-255-7875; Fax: 607-255-4471; Email: [email protected]

In recent years bacterial diseases of onion have increased in their economic importance to m New York onion growers. Bacterial bulb decay has approached 35 % in some storages. Research conducted during 1996-98 indicated when onions are topped only after the necks are dry, this form of bacterial decay can be reduced. Undercutting (all roots severed) and windrowing onions until the inside neck tissue is completely dry prior to harvest and topping should greatly enhance this method of control. Although application of copper fungicides has indicated bacterial decay control in some experiments, interpretation of the results must account for the relative succulence of neck tissue at jm harvest. If the fungicide did not adequately control onion leaf diseases, the bacterial decay levels most likely were regulated to a great extent by the level of neck succulence at harvest. Recent research has indicated that water in drainage ditches and slow moving streams is a source of bacteria which blight onion plants and decay onion bulbs. During F*i 1997 Burholderia cepacia was implicated as a cause of bacterial canker of onion plants. Envinia chiysanlkemi was proven to be the cause of a serious onion plant and bulb disease during 1995.

University of California. Davis Page 33 1998 National Onion Research Conference

Onion bacterial disease management in Colorado

Howard F. Schwartz and Kristen J. Otto Colorado State University, Dept. of Bioagr. Sci. & Pest Mgmt Fort Collins, CO 80523-1177 Phone: 970-491-6987; Fax: 970-491-3862; E-mail: [email protected]

Portions of the Colorado onion-growing region have dealt with a complex of bacterial diseases including Bacterial Soft Rot, Pantoea Blight, Sour/Slippery Skin and Xanthomonas Leaf Blight during the 1996 to 1998 growing seasons. Disease loss severities have varied in relation to adverse weather associated with rain and storm patterns. Disease management efforts have been enhanced by recent laboratory and field work with copper-based bactericides tank-mixed with EBDC fungicides. Results of these studies will be discussed in relation to an integrated pest management strategy for bacterial, diseases of onions in Colorado.

University of California. Davis Page 34 1998 National Onion Research Conference

Evaluation of fungicides and priming of seed for the control of onion smut, Urocystis cepulae Frost, on onions

MR McDonald, S. Janse and K Van der Kooi, Univ. of Guelph, Muck Crops Research Station Ketlleby, Ont. Canada Phone: 905-775-3783; Fax: 905-775-4546; E-mail: [email protected]. [email protected]. kvander@uo«ielph.ca

Onion smut is endemic in the organic soils of the Holland/Bradford Marsh area of Ontario, Canada. If emerging onion seedlings are not protected by ftmgicide, levels of smut infection range from 40 to over 90%. Currently, the seed treatment PRO GRO (30% carbathiin and 50% thiram) is the only fungicide registered for use on onions in Ontario. Field trials were conducted to determine if other fungicides or the use of primed seed would improve the control of onion smut. Evaluations of primed and unprimed seed from the same seed lot of onion cv's Quantum, Tornado and Hustler (1997) and Tribute, Festival and Copra (1998) failed to show any reduction in incidence of smut. Seed treatments Dividend (32.8% difenoconazole) and Raxil (8% tebuconazole) did not control onion smut, while Dithane DG (75% mancozeb) and Vitavax (97% carbathiin) in the seed furrow were effective. There is still a need for improved treatments to control onion smut under conditions favorable for disease development.

University of California, Davis Page 35 1998 National Onion Research Conference

Synthetic germination stimulants decrease incidence of smut {Urocystis cepulae Frost) on onions

MR McDonald and MHY Hovius Univ. of Guelph, Muck Crops Research Station Kettleby, Ont. Canada Phone: 905-775-3783; Fax: 905-775-4546; E-mail: [email protected],[email protected]

Trials were conducted in the greenhouse and in a commercial field to determine if products which stimulant the germination of smut teliospores would reduce the incidence of onion smut. For the greenhouse trial, naturally infested organic soil was collected from the field and mixed with either of the synthetic germination stimulants (DADS, at a rate of 1 ml/m2 in 50 ml of water ) or n-propyl disulfide (DPDS, at 1 or 2 ml/m2 in 50 ml water),obtained from United -Agri-Products. Treated soil was stored for three months then seeded with onion cvs. Taurus and Fortress. Onions, cv. Tribute, were seeded in 1998 in a field that had been treated with DADS(10 L/ha) in the fall of 1996 and 1997. Onions were assessed at the first and third true leaf and at harvest. In the greenhouse trial, DADS and DPDS at 2ml/m2 reduced the incidence on smut on cv. Taurus (39 and 29 and 62% respectively), but not on Fortress. In the field, DADS applications resulted in a small but significant reduction in incidence of onion smut. This is the first report that synthetic germination stimulants have the potential to reduce smut in onions.

University of California, Davis Page 36 National Onion Research Conference

Towards improved control of botrytis leaf blight of onion

M A Mutschler', E. D. Cobb1, J. W. Lorbeer2 m 'Dept of Plant Breeding and 2Dept of Plant Pathology. Cornell University, Ithaca, NY. 14853 Mutschler - Phone: 607-255-1660; Fax: 607-255-6344; E-mail: [email protected] Cobb - Phone 607-255-1714; Fax: 607-255-6344; E-mail: [email protected] Lorbeer - Phone: 607-255-7875; E-mail: [email protected]

Botrytis leaf blight of onion (BLB), caused by Bolrylis squamosa, is a major disease of m onions in New York state Over 80% of the active ingredients applied to onions are fungicides applied primarily to control BLB. Plant resistance offers an opportunity to reduce fungicide use. B. squamosa resistance has been reported in A. roylei, a wild species which produces fertile progeny with A. cepa. The F| hybrids between the two *** species are as resistant as A. roylei. Resistant selections have been made from Fj and BC populations, and are being used for production of further populations. Segregation data is consistent with a dominant resistance that is inherited simply. Another source of tolerance is A. cepa accession PI 273212, which Walters and Lorbeer identified as having m reduced BLB lesion number and lesion expansion. The inheritance of this tolerance is not known. It is critical to know potential for the resistance found in PI 273212 and in A. roylei to reduce disease without fungicide or with reduced levels or frequencies of fungicide application. A cooperative 1PM project is determining whether or not the m> resistance level found in this accession will permit control of BLB with fewer sprays or lower concentrations of fungicide.

University of California, Davis 1998 National Onion Research Conference

Susceptibility of onion seed stalks and flowers to infection by Aspergillus niger Teigh

Karen L. Sirois and James W. Lorbeer Department of Plant Pathology Cornell University Ithaca, NY 14853 Phone: 607-255-7850; Fax: 607-255-4471; Email: [email protected], [email protected]

The timing of onion seed stalk and flower susceptibility to infection by the fungus Aspergillus niger Teigh was evaluated in greenhouse experiments. Onion seed stalks and flowers received a one time inoculation of A. niger at 7 different stages of plant development. Half of each treatment received a 48 hour mist chamber treatment. The plants were allowed to mature with no further manipulations and the seed was collected when mature capsules formed. Evaluation of the seed revealed a broad susceptibility period to infection by A. niger. Plants inoculated prior to flowers opening through mature capsule formation, which included 5 different stages of plant development, were detected with high levels (82-100%) of A. niger on the seed. A seed infection level of 23% was detected on seed from plants receiving a one time inoculation to the immature seed stalk. Observations of A. niger mycelial growth and sporulation within the lacunar area were observed at the time of seed head collection. The addition of the mist chamber treatment did not indicate any increases or decreases in infection levels.

University of California, Davis Page 38 1998 National Onion Research Conference

Garlic seed clove treatments for the control of penicillium decay m R. M. Davis1, B. L Teviotdale1, J. J. Nunez3, and N. C. Goodell2 'University of California-Cooperative Extension, Davis 'University of California-Cooperative Extension, Kearney Ag Center 'University of California-Cooperative Extension, Kern County fm 31031 South Mount Vernon Ave, Bakersfield, CA 93307 Telephone: 80S-868-6222; Fax: 805-868-6208; E-mail: [email protected]

Poor garlic stands are often caused by Penicillium hirsutum. Although usually of minor m importance this disease occasionally accounts for substantial stand loss in California. Laboratory and field trials were conducted to evaluate various hot water dip treatments for the control of Penicillium decay. The experimental treatments were based on the Lear/Johnson (L/J) seed piece dips for controlling nematodes (30 minutes in heated water pK| to 100 F then 20 minutes at 120°F, followed by a 10 minute cool tap water dip). Formaldehyde was not used in any of the treatments. Various treatments differed by adding disinfectants or fungicides in the 10 minute cool tap water dip. Materials tested vm with the L/J treatment were sodium hypochlorite, benomyl, potassium sorbate, and imazalil. Treatments were evaluated with wounded and nonwounded garlic cloves. All cloves were inoculated with spores of Penicillium hirsutum. Field trials were conducted at two locations. Laboratory experiments were also conducted to assay the recovery of pm Penicillium hirsutum from the treated garlic cloves. In field and laboratory trials, L/J treatments with imazilil was the most effective and provided long-term protection against seed piece decay. Sodium hypochloroite provided good control but had no residual effect. The L/J treatment alone was also effective. There was little benefit to treating Tm healthy, nonwounded seed cloves.

University of California, Davis Page 39 1998 Nalional Onion Research Conference

Severe outbreak of garlic rust disease in California.

S. T. Koike, University of California Cooperative Extension, Monterey County R. F. Smith, University of California Cooperative Extension, San Benito County R. M. Davis, Department of Plant Pathology, University of California at Davis J. Nunez, University of California Cooperative Extension, Kern County

In 1998, severe rust disease of garlic was observed in several counties in coastal (Monterey, San Benito, Santa Clara) and inland (Fresno, Kern, Kings) California. Disease was widespread, and in many fields 100% of the plants were infected. Symptoms were often severe, resulting in death of most leaves and significant stunting of bulbs. At harvest affected garlic was substandard in quality and size, and some cultivars shattered when collected. Based on the yellow orange urediospores and two-celled teliospores with short pedicels, the rust was identified as Puccinia porri. Pathogenicity was established by inoculating greenhouse grown garlic with isolates collected from the field. Inoculated garlic developed rust after 9 to 12 days. The same isolates also infected and several onion cultivars, but did not infect or . Commercial onion fields adjacent to or near infected garlic also became infected with the rust, although disease in general was less severe than on garlic. Small plot fungicide trials demonstrated that several fungicides were not effective against the disease (such as Bravo, Maneb, Mancozeb), but that other, non-registered materials (Folicur, Quadris) potentially will control it Garlic rust is not a new disease to California, as it was reported in the state as early as the 1930s. However, the severity, distribution of the problem, and devastating crop loss appear to be unique developments.

University of California, Davis Page 40 IW8 National Onion Research Conference

Damage threshold for thrips on processing onions in the San Joaquin Valley, California

Richard L. Coviello, U.C. Coop. Extension, 1720 S. Maple Ave, Fresno, CA Phone: 209-456-7549; Email: rJ.csyiel!fl@«£davi8,.ffli«

Milton E. McGiflfen, Jr.. Dept. Botany and Plant Sciences U. C, Riverside Phone: 909-787-2430; Email: [email protected]

Thrips cause considerable damage to onions. Localized tissue necrosis from their feeding reduces the photosynthetic ability and nutrient availability to the plant for setting and sizing the bulb, which consequently reduces yield. Reliable estimates of the population level of thrips, which significantly reduces yield, have not been available for processing onions grown in the San Joaquin Valley, California. Replicated plots were established at the University of California West Side Research and Extension Center in 1994, 1995 and 1997. Sprays of cypermethrin at various intervals, plus an untreated check, resulted in significantly different populations of thrips developing across treatments. Thrips populations were sampled weekly using whole plant samples until plant maturity. Thrips counts were converted to cumulative thrips-days (CTD). Plots were harvested with a mechanical digger and data for plot total weight, harvestable weight, bulb weight, percent undersized and percent soluble solids were collected. Harvestable yields, bulb size and percent soluble solids were negatively correlated with thrips population. The data suggest that a range of 500 - 600 cumulative thrips-days or higher significantly reduces yield.

University of California, Davis Page 41 IW8 National Onion Research Conference

Evaluation of treatments for onion thrips control

Ronald F. L. Mau and Laura Gusukuma-Minuto m University of Hawaii at Manoa Department of Entomology 3050 Maile Way, Honolulu, HI 96822

More than 20 million pounds of onions are annually consumed in Hawaii. In-shipments account for about ninety percent of the market supply. There is a well-established industry that produces about 2 million pounds for the local and export market. The p* sweet onion and pungent onion industry is in an expansion phase. They hope to significantly reduce or completely replace in-shipments.

Thrips tabaci is a key pest of onions. Growers feel that the pest is not readily controlled r*m using organophosphatc or carbamate insecticides. Field studies with EPA approved and new insecticides were conduced to identify efilcaceous ones, to evaluate treatment thresholds, and to evaluate an insecticide resistance management protocol. Insecticides that were evaluated were diazinon (DIAZINON AG 500, Premiss Incorporated), m malathion (Malathion 5 EC, Drexel Chemical Company), methomyl (LANNATE L, DuPont), and lamdacyhalothin (WARRIOR, Zeneca Ag Products). New insecticides evaluated were chlorfenpyr (ALERT 2 SC, American Cyanamid), fipronil (Rhone ^ Poulenc), and spinosad (Dow Agrosciences).

University of California. Davis Page 42 1998 National Onion Research Conference

Evaluation of garlic extract for control of corn earworm, Helicoverpa zea, in sweet corn

Benny Fouche & Dawn Brunmeier U.C.C.E. San Joaquin Co. 420 S. Wilson Way, Stockton, CA 95205 Phone: 209-468-9491; Fax 209-462-5181

Helicoverpa zea is a major pest of sweet corn. The night-flying moth lays its eggs on the silks of the com ear. Insecticide applications of synthetic pyrethroids and or organophosphates may be necessary every 2 to 3 days for a period of several weeks to prevent infestation when the corn is susceptible. Five applications of Garlic Barrier plus fish oil were made and compared to Asana, Success, JMS Stylet Oil and an untreated control in a commercial planting with a high population of corn earworms At harvest, the untreated control had a mean level of 48% worms in the ears. Asana provided the best control with less than 2% worms. Garlic Barrier plus fish oil, JMS Style oil and Success provided significantly better control than the untreated check with a range of 8- 12% ears with worms present at harvest.

University of California, Davis Page 43 1998 National Onion Research Conference

Weed control with dimethenamid in onions growing on organic soils

L. A. Ellerbrock and B. L. Phillips Department of Fruit and Vegetable Science, Cornell University, Ithaca, NY 14853 Phone: 607-255-6553; Fax: 607-255-0599; E-mail: [email protected]

Field and greenhouse experiments have shown that dimethenamid, applied at various timings and rates, is relatively safe on onions growing on organic soils in New York and would be very effective in enabling growers to manage yellow nutsedge, a weed that has become increasingly difficult, if not impossible, for New York growers to control in recent years. Dimethenamid would also be very useful in managing other problematic weeds in onions, including Galinsoga, prostrate spurge, common ragweed, and redroot pigweed. In most situations, dimethenamid rates of at least 1 Ib a.i./A are required for adequate yellow nutsedge suppression, and in many cases, up to three such applications are needed. Application of dimethenamid is compatible with the use of broadcast small grain windbreaks for early season wind abatement, and tankmix applcations of dimethenamid with grass herbicides for removal of windbreaks are effective and safe. When applied in a tankmix with pendimethalin shortly after onion emergence at rates up to 1 1b a.i./A, dimethenamid does not increase onion injury. Dimethenamid can also be applied safely and effectively in a preemergence tankmix application with bromoxynil for early season broadleaf weed control.

University of California, Davis Page 44 1998 National Onion Research Conference

y/wj The use of foliarly-applied nitrogen fertilizers for early-season weed control in onion seed crops ra Mike Murray University of California Cooperative Extension P. 0. Box 180 Colusa, California 9S932 i"9 Phone: 530-458 0577; Fax: 530-458 4625; email: [email protected]

Early-season weed management is a challenge for both fresh market bulb or onion seed _ producers. This situation has been exasperated by the recent market withdrawal of the onion preplan! herbicide. Dacthal®. There are effective post-emergence herbicides available, so the immediate need is for effective weed control for the period from seedling emergence to the 3 -4 true-leaf growth stage. Researchers have previously noted rm that the use of foliar nitrogen fertilizers, such as ammonium nitrate, often results in weed seedling control and minimal damage to young onions. The basis of this selectivity appears to be the waxy cuticle on onions, which causes the fertilizer to run-off the foliage. The fertilizer behaves as a salt on weed foliage and desiccates the plants. It m should be noted that most nitrogen fertilizers are not registered as pesticides in California, and they can not be legally recommended or used exclusively for this purpose (although they can be used as foliar fertilizers with "side-benefits" of weed control). Tests were conducted in onion-seed fields in the lower Sacramento Valley in the fall of 1997 and |B!*1 1998. Application timings, rates and fertilizer formulations were evaluated in multiple tests. The fertilizers were applied in the onion "crook" through several true-leaf stages and when the weeds had less than four true-leaves. The primary weed species present m was Shephardspurse (Capsella bursapasioris). Safety to the crop, at all growth stages, and weed seedling control was excellent.

University of California. Davis Page 45 Session 5 Crop Culture, Physiology, Growth, Storage 19'J8 National Onion Research Conference

Do onions have a critical plant size for bulb formation?

m H.C Wien, B.S. Orenstein and LA. Ellerbrock Department of Fruit and Vegetable Science Cornell University. Ithaca, NY 14853 Phone: 607-255-4570; Fax: 607-255-0599; E-mail: [email protected]

When onion cultivars of a range of maturities are planted in spring in New York State, they initiate bulbs several weeks after daylength and temperatures are adequate for bulbing. Is this apparent delay in bulbing due to a minimum plant size, which a particular fm cultivar might need to attain before bulbing could begin? The results of a series of field and greenhouse plantings of 10 cultivars ranging in adaptation from Texas to Northern Europe indicate that even the northern long day types can be induced to begin bulbing when neck diameter is only 6mm, by sowing the seeds when temperatures and photoperiod are optimum for bulbing. The bulbing ■ delay in spring plantings could therefore be due to the somewhat lower temperatures prevailing then, or the need for long-season cultivars to be exposed to more cycles of inducing conditions, before bulbs j~r, are initiated, or both. Sowing in June leads to quick bulb initiation, but maturity is prevented by the short daylengths and cool temperatures of fall. The implications of these findings on selection of onion genotypes for environmental stability and yield will be discussed.

University of California. Davis Page 46 1998 National Onion Research Conference

Alternative onion transplant production in Colorado m Michael E. Bartolo and Frank C Schweissing Colorado State University, Arkansas Valley Research Center 27901 Road 21, Rocky Ford, CO 81067 Phone: (719)254-6321; Fax: (719)254-6312; e-mail: [email protected]

Onions grown from transplants are a significant part of the total onion crop produced in Colorado. Bare-root transplants are grown in southern states and transported to Colorado f*1 for planting in early spring. These transplants often harbor insects or diseases that infect the growing crop and spread to direct-seeded onions. Additionally, the cost and availability of labor have made onion transplanting more difficult These studies were conducted to examine the feasibility of alternative transplant production methods. In P" 1995 through 1998 several alternative transplanting methods were examined, including containerized greenhouse production, in-field transplant production under row covers, and fall planting-to-stand with and without row covers. Greenhouse-grown onion Fm transplants were free of pests and produced high quality onion bulbs Transplants grown at a high density (392 cells per flat) and a lower density (200 cells per flat) produced onions comparable in yield. Onion transplants grown locally under row covers had few pests and resumed growth rapidly after transplanting. Unfortunately, hand labor inputs m were still significant. Planting to stand with and without row covers eliminated much of the hand labor associated with traditional onion transplanting. However, additional research will be needed to identify varieties that are more winter-hardy and less prone to bolting.

University or California, Davis Page 47 HW8 National Onion Research Conference

Sudan grass Rotation for Improved Yield and Quality of Onions Produced on Organic Soils in New York

John J. Mishancc Cornell Cooperative Extension, 1PM Program PO Box 497, Martin Rd. "*• Voorheesville, NY, 12186 Phone: 518-765-3532; E-mail: [email protected]

There are close to 5600 acres of onions grown on organic soils in Orange County, New m York. Over the years, onion growers have expressed an interest in learning ways to increase fertility of their high organic (muck) soils. In some cases, fields have been in uninterrupted onion production for two or more generations. One idea is using rmfi Sorghum/Sudan grass (Sudex) as a summer cover crop. The goal of these field trials with Sorghum/Sudan grass were to figure out all the basic management considerations and document the positive and negative results. After 6 years of in field trials, here is what we have learned.

* Handling the large bio mass of Sudangrass takes some management. Planting rates must be adequate to smother out weeds. Mowing half way through the summer stimulates tillering and root penetration. Fields need to be cut and disced down early in ™ the fall to avoid trash and nitrogen deficiency problems the following spring * Onions following Sudangrass can expect a 35% average increase in stand counts * An average 20% increase in yield can be expected. * Following a Sudangrass rotation, growers can reduce onion planting rates by 15-20%. pw * Quality was at least as good or better in the Sudangrass fields as compared to the continuous onion fields Given the varying weather conditions, these results must be considered very good. Onion growers who employed the Sudangrass rotation say the p_, onions following Sudangrass were their best onions and secondly, the growers felt the numbers we found in our test plots were low. For most years, the growers felt they received an even bigger yield response than what we found in the test plots. * Two years after a Sudangrass rotation, yields and stand counts were still positively ™ affected but decreased slightly from first year after rotation. * With a five year whofe farm rotation, a grower will be ahead on return plus savings on onion seed, labor and pesticides.

University of California, Davis Page 48 .1 Of|i»n KcMifch ConfatlKc

Non-destructive measurement of quality parameters of stored onion

Zsuzsanna Fiistos \ J6zsef FelfbldiJ, Sandor IstellaJ University of Horticulture and Food Industry 1 Postharvest Department department of Physics and Control 1 Department of Vegetable Growing H- 1118 Budapest Villanyi ut 35-43 Phone/fax: 36-1-466-52-94; E-mail: [email protected]

The onion is stored for eight to nine month every year in Europe, and gets consumed after storage. The efficiency of the onion storage is determined by the storage time without any quality decay. The damaged, rooted, or sprouted onion is worthless on the market. Because of the reasons above storability and effective parameters are very important in the case of onion.

Most of the traditional methods and tools are based on destructive test (fructometers, precision penetrometers) causing injury. Our aim was to find non-destructive method for measurement of the firmness of onion bulb giving good correlation with the traditional methods and suitable to measure the structural changes of the same piece of crops during the storage period.

The tested samples were stored at different conditions. One part of the amount was kept in refrigerator, at 4°C (cooled). In the cellar the temperature was at 12-13°C. We have measured and calculated the colour ,the shape, the firmness parameters, coefficient of elasticity, secant modulus, acoustic stiffness coefficient and the sprout length and evaluated the correlation among them. No significant differences were found in visual parameters during the storage methods.

Our results give possibility to determine characteristic ranges of the firmness parameters for different quality (sprout length) categories

Both of the secant modulus and the acoustic stiffness coefficient were found to be suitable to classify the samples according to the sprout length categories. The acoustic response method - due to it's non destructive nature and real- time result - can be the base of on-line selection method.

University of California, Davis a| Onion Rcwch Conference

Long-term storage potential of garlic (Allium sativum L) with cryopreservation and regeneration in tissue culture

Richard Hannan and Denise Garoutte USDA, AM, Western Regional Plant Introduction Station 59 Johnson Hall, WSU, Pullman, WA Phone: 509-335-1502; Fax: 509-335-6654; E-mail:

The USDA, ARS, NPGS maintains a collection of Allium species at the Western Regional Plant Introduction Station, Pullman, WA. The collection currently numbers 823 accessions, with m over 230 vegetatively propagated. Clonal accessions are planted in the fall and harvested the following summer. This subjects germplasm to potential loss from adverse weather or disease. Research was conducted to explore cryopreservation under liquid nitrogen (LN) for long-term storage of garlic. Tissue culture maintenance was rejected due to cost, space and labor m requirements, and the potential for genetic drift. The objectives were to reproduce existing protocols for tissue culture establishment of garlic, develop a successful protocol for LN storage of garlic clones and test the effectiveness of the protocol over a range of genotypes. Prior to immersion into LN, plant tissue must be chemically conditioned Of the conditioning treatments |PP* tested, ones which used 50% to 74% PVS2 and 50-26% water/sucrose solution were most effective. Dehydration and pre-treatment on a high sucrose medium favored survival Effect of explant size on survival indicated that either 2mm or 5mm explants survived and that the m conditioning treatment was most crucial. No explants survived thawing in temperatures of 40°C Survival was best at 20 minutes and I7°C. In the study of genetically different clones, results were statistically inconclusive due to losses from contamination. Data indicates that use these protocols for crypreservation of the USDA garlic collection is feasible.

University of California, Davis Page 50 Posters IW8 NiliwMl Ottian Re»t»ch Conference . —

Fall-planted onion variety trials at New Mexico State University

Christopher S Cramer, Jose Luis Mendoza and Joe N. Corgan Department of Agronomy and Horticulture, New Mexico State University MSC 3Q, Box 30003, Las Cruces, NM 88003-8003 Phone: 505-646-2657; Fax: 505-646-6041; E-mail: [email protected]

Forty-two fall-planted onion varieties and lines were tested in 1998 at the Fabian Garcia Agricultural Science Center in Las Cruces, NM. Four replications of 2.5 m-long-plots for each entry were planted on 16 September 1997 with 4 rows per bed per plot. This planting date was chosen to evaluate varieties for bolting resistance. Varieties were arranged in a subplot based upon approximate bulb maturity (early, intermediate, late) for fall planting in Las Cruces, NM. Varieties were harvested when 80% of the tops were down in all four replications. Varieties were evaluated for maturity date, pink root and bolting resistance, total and marketable bulb number and weight, and percentage of marketable bulbs. Bulb maturities ranged from 14 May ('Buffalo') to 19 June (NMSU 9712). Most early-maturing 'NuMex' varieties and NMSU breeding lines exhibited a low percentage of bolting along with 'Ibex' and 'Buffalo'. Most entries except 'Buffalo' exhibited moderate to high levels of pink root resistance. Some of the high-yielding (based on weight) entries included 'NuMex Sunlite', 'NuMex Mesa", 'NuMex Starlite', 'NuMex Dulce*. NMSU 96-11, 'Caribou', and 'Ibex'.

University of California, Davis ' Poster I IOTH N«lion»l Onion Rj«tMch C'onrtTcnc-

Seed yield and morphology of CMS onion populations possessing the cytoplasm of A. galanthum

Michael J. Havey, USDA-ARS and Dep. of Horticulture 1575 Linden Dr., University of Wisconsin, Madison, Wl 53706 Phone: 608-262-1830; Fax: 608-262-4743; Email: [email protected].

The primary source (S cytoplasm) of cytoplasmic-genic male sterility (CMS) used to produce hybrid-onion (Allium cepa) seed traces back to a single plant identified in 1925 in Davis, CA. Many open-pollinated populations also possess this cytoplasm, creating an undesirable state of cytoplasmic uniformity. Transfer of cytoplasms from related species into cultivated populations may produce new sources of CMS. In an attempt to diversify the cytoplasms conditioning male sterility, the cytoplasm of was backcrossed for six generations to bulb-onion populations. The flowers of galanthum-cytoplasmic populations possess filaments with no anthers and upwardly curved perianth, making identification of male-sterile plants easier than Tor either S- or T-cytoplasmic male-sterile onion plants. Mean seed yield per bulb of the galanthum-cytoplasmic populations was measured using flies as pollinators and was not significantly different from that of one of two S-cytoplasmic male- sterile F| lines, a T-cytoplasmic male-sterile inbred line, or N-cytoplasmic male-fertile lines Male sterile lines possessing S and galanthum cytoplasms were crossed with populations known to be homozygous dominant and recessive at the nuclear locus conditioning male- fertility restoration of S cytoplasm and progenies scored for male-fertility restoration. Nuclear restorers of S cytoplasm did not condition male fertility for the galanthum- cytoplasmic populations It is intended that these galanthum-cytoplasmic onion populations be used as an alternative male-sterile cytoplasm for the commercial production of hybrid- onion seed.

University of California, Davis Poster 2 1998 Nuioial Onion Rqgfdi Confaenct

The Vidalia onion industry: past, present, and future

George Boyhan "*< University of Georgia, East Georgia Extension Center PO Box 8112, GSU, Statesboro, GA 30460 Phone: 912-681-5639; Fax: 912-681-0376; Email: [email protected] fm The Vidalia onion industry that began in 1931 has seen slow but steady growth until the 1970s. In the 1970s a concerted effort was launched to market these onions nationally, which resulted in a tenfold increase in acreage over the next decade. In 1986, Georgia gave ^ recognition and legal status to the Vidalia onion industry, defining the 20 county production area. This was followed in 1989 with Federal market order 955 that gave the industry legal status on a national basis. In addition, in 1989 the industry began to adopt controlled atmosphere (CA) storage The size of the industry has more than doubled since the mid- rm 1970s and stands at more than 14,000 acres today. Problems the industry faces include new diseases not seen in this region before, labor problems associated with the use of foreign labor, increased competition, problems with CA storage and problems associated with adoption of mechanized harvesting.

University of California, Davis Poster 3 1998 N.lion.1 Onion RtMMdi Confacnw

Onion and garlic research in India

H.S. Dalla, AS. Sidhu and S.S. Bal FW Punjab Agricultural University, Ludhiana 141 004 Punjab INDIA

im Onion and garlic both are important commercial vegetable crops among various Alliums growth in India. India ranks first in the hectarage of onion and second in garlic, comprising 0.36 million hectare under onion and 0.08 million hectare under garlic. In production however, it stands second and fourth with 3.6 million tons and 0.26 million tons respectively. m India exported 446,000 tons of onion valued at Rs. 2430 million which accounted for about 75 per cent of total foreign exchange earning among fresh vegetables There has been a steady increase in both area and production in the last decade Besides, the traditional winter season crops, the summer crop is now being grown successfully in the north and eastern parts P"* of the country. In spite of this, productivity remains lower than the world average. The low productivity in these crops has been accounted or a host of factors including diverse agro- ecological situations, lack of suitable varieties and non scientific cultural practices, etc. Several biotic and abiotic factors have also been identified as limiting the productivity. ™l Major emphasis has been put on the improvement of the productivity Special attention is being paid to build a large germplasm base for these crops. Developing lines with higher levels of resistance to major prevalent diseases besides developing tolerance to high temperature and moisture prevalent have been earmarked in priority areas Poor storage quality of onion bulbs is one of the major constraints which require immediate attention. Heterosis breeding in onion has also been initiated. India has developed several important cultivars of onion and garlic for different agro-climatic zones and are classified on the basis im of size, season and skin colour of the bulbs Most popular among them for onion are Pusa Red, Pusa Madhvi, N-2-4-1, Punjab Selection, Punjab Red, Round, Punjab Naroya, ALR, Pusa Ratnar, HISSAR - 2, Arka Niketan and Arka Kalyan in red types whereas Pusa white Flat, Pusa white Round, Pb-18, Punjab white, Udaipur • 102, N-257-9-1 and RHR white m among white types have been developed for rabi season and ADR, N-53, B-780 and Arka ! Kalyan for Kharif season in case of garlic Agri found white, G-l, G-SO, Godavari Sweta have been developed.

University of California. Davis Poster 4 IW* Niliwul Opii»p H^rdi Conference .

Onion growth and N uptake in southeastern Colorado

Ardell D. Halvorson, Ronald F. Follett, and Michael E. Bartolo m USDA-ARS and Colorado State University P 0 Box E, Fort Collins, CO 80522 Phone: 970-490-8230. Fax: 970-490-8213; e-mail: adhalvor(S)lamar colostate edu

Onion (Allium cepa) production in southeastern Colorado may be contributing to high levels of NOj-N in irrigation and groundwater supplies. Normal N fertilization rates range from 100 to 400 kg N/ha. Frequent irrigation of onions is needed at the seedling establishment stage to m help onion survive the hot, dry climate of southeastern Colorado. Therefore, the potential for N leaching is high. We conducted a study in 1998 to examine the growth and N uptake patterns of onion grown on a Rocky Ford silty clay soil. Plant samples were collected at two week intervals from April 22 through mid-September 1998 from plots receiving no N ^ fertilizer and plots receiving 224 kg N/ha The N fertilizer (KNOj) was applied in split applications of 112 kg N/ha each on May 18 and June 25, 1998 In addition, labeled N fertilizer (112 kg N/ha as KN1' O3) was applied to separate plots that had received 112 kg N/ha of non-labeled KNOj at each of these N application dates. A randomized complete TSR block design with three replications was used. Preliminary results indicate that biomass production was very low during the first 76 days following planting with a rapid increase in biomass production during the next 24 days. No response of onion to N fertilization was observed during the first 106 days of growth. Onion biomass production and N uptake patterns from planting to harvest will be presented.

University of California. Davis Poster J 1998 Nniiofwl Onion Reswch Conference

Irrigation scheduling to optimize yields and reduce leaching of nitrates for Maui sweet dry onions

i™1 Robin S. Shimabuku and I-Pai Wu Hawaii Cooperative Extension Service University of Hawaii 310 Kaahumanu Ave. B Idg. #214 Kahului, HI 96732 And Department of Biosystems Engineering pm. University of Hawaii at Manoa 3050 Maile Way Honolulu, HI 96822 Phone: (808) 244-3242; Fax: (808) 244-7089; email: Shimabukurtgavax ctahr hawaii edu p> Phone: (808) 956-8809; Fax: (808) 956-9269; email: [email protected]

Deep seepage of nitrates in agricultural fields is an important non-point source pollutant for underground water resources in Hawaii. The leaching of nitrates can be minimized with a Fm highly uniform drip irrigation system and appropriate scheduling based on onion water requirements.

Three field experiments were conducted from 1996 to 1998 in Kula, Maui using 10 different irrigation scheduling rates. A simple drainage lysimeter was installed for each treatment to determine the amount of nitrate leaching out from the root zone

&SH Results from these experiments have shown the ET (evapotranspiration) rate were very similar to the total evaporation rate for the crop cycle to obtain optimum yields and that deep seepage only occurred in irrigation treatments exceeding the ET for optimum yield. This data suggest using a Class A evaporation pan to determine the water requirement of onions f™ for given period of time. For every inch of water being evaporated by the evaporation pan, an acre-inch (27,154 gal) of water needs to be applied per acre of onion crop. By using this method, the water requirements of onions can be determined for optimum yields and to help minimize groundwater contamination of nitrates by over irrigation

University of California, Davis Poster 6 1998 National Onion Rwewch Conference

Effects of Transplant Date and Transplant Size on Production, Quality, and Pungency of Sweet Onions m Mark Gaskell, Marita Cantwell, Xunli Nie, Richard Smith, Ben Faber, and Ron Voss Department of Vegetable Crops, University of California, Davis, CA 9S616 Phone: 805-934-6240; Fax: 805-934-6333; Email: [email protected]

The production of short day sweet onions in temperate zones is limited to areas with mild winters and appropriate day lengths for normal development. Previous studies in Coastal California showed excessive bolting with short day onions transplanted prior to early im January. Later transplanting and smaller transplant size can reduce bolting.. This study evaluated 4 short day cultivars grown in 3 transplant tray sizes (280, 392, or 595 cells per tray) at 3 transplant dates (Jan.27, Feb. 13 or Feb. 27) Bulb sizes generally declined with each successive transplant date across cultivars and cell sizes. The smallest transplant size f™ produced the smallest onions in all cultivars in the Jan. 27 and Fcb 13 plantings Harvested bulb size and transplant cell size was inconsistent with the latest planting date, with smaller bulbs from the largest transplant size in 3 of the 4 cultivars. Generally transplant date did not affect pungency, dry weight, or sugar concentration, with average values across cultivars and m locations of 4.2 (range = 2.9-5.6) umole pyruvate/g fr.wt., 7.9 (range = 6.6-10 2) % dry wt, and 42 (range = 29-49) mg/g fr. wt., respectively. Location, however, resulted in important differences, with pungency values at 2 locations of 4.7-5 0 and at the other two of 3.3-3.6 umole pyruvate/g fr.wt.

University of California, Davis Poster 7 I'W» N«Ik«mI Onion knalJl Confctciwc

Synthetic garlic oil reduces viability of Sclerotium cepivorum sclerotia and incidence of white rot on onions

McDonald MR and Hovius MHY Muck Crops Research Station, University of Guelph 1125 Woodchoppers Lane, Kettleby, ON, LOG 1 JO Phone: 905-775-3783; Fax: 905-775-4546; E-mail. [email protected]

Allium white rot (Sckrotium cepivorum) is a major threat to the onion industry in Canada, where most of the crop is grown on organic (muck) soils. Disease incidence can exceed 65% in commercial onion fields. Materials such as onion oil and synthetic garlic oil are known to stimulate the germination of sclerotia of S. cepivorum in the absence of a host, reducing the soil populations [1,2]. Trials were conducted in commercial onion fields and in the greenhouse to determine the potential of germination stimulants to reduce sclerotia populations and subsequently control white rot on onions. Two germination stimulants, diallyl disulfide (DADS) and N-dipropyl disulfide (DPDS), were applied to field plots (65% organic matter, pH 5.5-6 5) in the Holland Marsh, Ontario, naturally infested with the pathogen. The materials were injected at depths of 10 and 20 cm, at rates of 10.01/ha in 500l/ha of water at sites 2 and 3 in 1994, at sites 4 and 5 in 1995 and 1996, at site 6 in 1996 and at sites 7 and 8 in 1996 and 199.7. Only DADS (5.01/ha) was applied to site I in 1994. Adjacent untreated areas were used as controls with six replications per treatment. Onions were grown at sites 1, 2 and 3 in 1995, sites 4 and 5 in 1997 and sites 6, 7 and 8 in 1998 and evaluated for white rot at harvest. Mesh sacks of 100 sclerotia of S. cepivorum were placed in pots of organic soil treated with DADS and DPDS (1 ml/m2 in 50 ml water) and recovered at monthly intervals. Sclerotia were plated on potato dextrose agar to test for viability. Incidence of onion white rot was relatively low in all years (maximum 13.7 and 13.0%, respectively). Single treatments with DADS significantly reduced white rot on onions at sites I, 2 and 6 (reductions of 72, 88 and 81% respectively), while two applications of DADS reduced white rot by 99, 100, 87 and 96% (sites 4, 5, 7 and 8 respectively). Exposure of sclerotia to DADS and DPDS in pots of treated soil reduced viability after 2 and 3 months, but DADS much more effective than DPDS (18 and 60% viability, respectively, compared to 99% for the water check). DADS is an effective soil treatment for the control of onion white rot in organic soils, especially when applied twice prior to onion production. The effectiveness of DPDS may be improved by increasing the rate.

References

1. Crowe FR, J Dobons and T Darnell. 1994. Proceedings of the 5* International Workshop on Allium White Rot, 5.2b

2. Utkhede RS and JERahe, 1981. Canadian Journal of Plant Pathology. 4:79-80

University of California, Davis Posler 8 IWX Nalionul Onion Kc»c»ich ConftKIKC

Base temperature for garlic growth determinations in the white-garlic type

J. A Portela, J. L. Burba and S. Lanzavechia Garlic Project, EEA La Consulta INTA CC 8 (5567) La Consulia, Mendoza, Argentina Fax: +54-622-70 753, E-mail, [email protected] ar

Temperature is the main environmental factor that affects growth and development of garlic (Allium sativum L.). Although many studies on its physiology have been carried out alt over the world, few of them have tried to describe associations between temperature and growth so far. The aim of this work was to establish base temperature for the white garlic type (physiological group III for Argentine and French classification). Three monoclonal cultivars - Lican INTA, Nieve INTA and Union - were grown in growth chambers at constant temperature (0, 6, 9, 12, 2I°C) and in the field. Clove sprouting as the appearance of the sprout leaf over the ground in the first case, and the number of foliage leaves in the second was periodically recorded. The physiological base temperature in the sprouting phase was established below 0°C for all cultivars. In the field, a base temperature of 0°C was more appropriate for use in a linear system of heat units. Even though it was not possible to differentiate minimum temperature requirements among cultivars, they showed diverse trends of response as the temperature varies

University of California, Davis Poster 9 IW8 Nilioml Onion Kwoi

Development of a bioassay to determine the presence of specified fungal pathogens of onion.

Karen L. Sirois, David P. LoParco, and James W. Lorbeer Department of Plant Pathology Cornell University Ithaca, NY 14853 Phone: 607-255-7850; Fax. 607-255-4471; Email: [email protected], dpll@ cornell.edu, andjwl5@ cornell.edu

A bioassay was developed to determine if pathogenic fungi detected on onion seed were capable of infecting developing seedling tissue. Spores of an Alternaria sp, AspergUlus sp., AspergUlus niger, Fusarium sp., and Penicllium sp. were used to inoculate onion seed and were placed in the soil growth medium to determine the infection levels in the onion seedling tissues. Seedling tissues were examined at various ages for the presence of the fungi used in the inoculations. The seedling parts examined were the roots, basal plates, lower leaves, leaf tips, and the seed coat remnants if they remained attached to the leaf tips. Isolation of the inoculated fungi was most consistent in treatments which utilized AspergUlus niger and the Fusarium sp. Seed inoculations and soil growth medium placement of spores produced similar infection levels. The infections appeared to begin in the root systems of the seedlings and moved systemically into the basal plates and lower leaves.

University of California, Davis Poster 10 1W8 N.lioml Onion R<««rch ConfwciK*

Pest Management Guidelines: Onion and Garlic from the University of California Statewide IPM Project

R. Voss, R. Coviello, W. Chaney, W. Bentley, S. OrlofT. R.M. Davis, F. Laemmlen, C. Bell.H. Agamalian, D Cudney, B. Fischer, B. Westerdahl, U. Kodira, ML. Flint, B. Ohlendorf

IPM Education and Publications University of California, Davis CA 93616 Phone: 530-752-7821; Fax: 530-752-9336; [email protected]

The UC IPM Pest Management Guidelines for Onion and Garlic contain the official University of California suggestions for managing insect, mite, disease, nematode, and l^r weed pests. Written by UC faculty and advisors with expertise in onion and garlic, the guidelines represent the best information currently available and are intended to assist growers in making the best choices in an 1PM program. Included in each pest section is a ra brief description of the pest, its damage, monitoring and treatment timing suggestions, nonchemical and/or cultural control methods, pesticides, and special problems. Guidelines are updated as pest management options (including pesticides) change. UC IPM Pest Management Guidelines are available for approximately 40 California crops. The Onion pb and Garlic Guidelines can now be purchased together with a new color photo supplement illustrating common pests as UC DANR Publication 3339-PS3A. The UC Statewide 1PM Project has also produced comprehensive 1PM manuals for 15 major California crops including potatoes, tomatoes, lettuce and cole crops, alfalfa, cotton, strawberries, and r"!r numerous fruit and nut trees Guidelines with color supplements have been produced for onion/garlic, sugar beet, and dry beans. These publications may be purchased from UC DANR Communication Services or from UCCE County offices. Guidelines may also be viewed on the web at .

University of California, Davis Poster 11 199* Nilioml Omon Koewh Confcttin-v

Polymorphism in AUinm species revealed by Simple Sequence Repeats

Ellen PefTley1, Anfu Hou1, and Laurence Trueman2 'Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409, USA; horticulture Research International, Wellesbourne, Warwick, CV 35 9EF, UK.

Simple sequence repeats (SSRs), also referred to as "microsatellites", are tandemly repeating short nucleotide units of 6bp or less. SSRs are relatively abundant in plants, highly variable, and easily detectable by PCR. For these reasons, these are a highly desirable class of molecular markers. An initial investigation of SSRs in onion was conducted at Horticulture Research International, Wellesbourne. In the study reported here, DNA clones containing SSRs were identified from small insert random genomic pJVl DNA libraries of leek (Allium ampeloprastim). Oligonuclcotide primers flanking the SSR regions were designed and the amplification conditions optimized. These primers were used to amplify genomic DNAs from cullivars of several species ofAllium.

University or California, Davis Poster 12