Onion World: The Voice of the Onion Industry

Onion Field Day Reports….

Onion World
November 2007

Demonstration and Field Day
Held on Hartley Farms on the Horse Heaven Hills, northeast of Paterson, Wash., this year’s Washington State University Onion Cultivar Demonstration and Field day drew a sizeable crowd.

Visitors compared onion cultivar entries from Sakata Seed, Nunhems, Seminis, Nippon Norin, Bejo Seeds, Global Genetics, Crookham Company, American Takii and D. Palmer Seed.

Brief presentations were made by Bob Stevens, Troy Peters, Doug Walsh, Rick Boydston and Brenda Schroeder, all with Washington State University. The day wound up with a barbecue luncheon.

Nortron Option
Stevens reminded growers that Nortron has been registered for pre-emergence use on onions.

“It was a long, drawn-out process,” he said, pointing out that he had tested the material pre-emergence on heavier soils roughly 10 years ago in the Prosser area. While there were no problems at that time, he said he felt it wise to test Nortron again this year, only on sandier soils.

Last spring, Stevens said he tested Nortron in strip trials in several fi elds with sandy soil. In some, the pre-emergence Norton was placed on top of a Dacthal application; it others, it was not. On seven different varieties examined, no injuries were detected.

“I feel pretty confi dent about using Nortron as a pre-emergence treatment,” Stevens said, adding that both early and late applications seemed to produce good control.

Weed Research Findings
Rick Boydston, a weed scientist with the USDA-ARS, IAREC, Prosser, highlighted a few observations from his 2007 onion weed research.

Yellow nutsedge is a perennial weed that is difficult to control, he affi rmed, speaking of control studies under way in the Pasco, Washington area. Field and outdoor container trials are being conducted there that target yellow nutsedge control in onions with Dual (s-metolachlor), Outlook (dimethenamid-p), Sparta (Sulfentrazone) and Basagran (bentazon). “Dual and Outlook are being tested at the 2-leaf onion stage and also as split applications at 2-leaf and 3- to 4-leaf stage,” he said. “Dual and Outlook are the two most promising treatments, exhibiting the least amount of onion injury. Outlook has a national label on onions and Dual Magnum has an SLN label (for Walla Walla sweet onion growers only) when applied at the 2-leaf stage or later.

“Spartan and Basagran treatments resulted in excessive amounts of onion injury at rates suffi cient to suppress yellow nutsedge. Onion injury and yield data are being collected from each treatment. Yellow nutsedge tubers were also planted in outdoor container trials to better evaluate the same herbicide treatments on yellow nutsedge tuber production,” he explained.

In the Prosser, Washington area, onion tolerance to Starane (fl uroxypyr) is being evaluated by applying the product at two rates at the 3- and 5-leaf stages, and by applying it in sequential applications at the 3-and 5-leaf stages. Starane has had a Section 18 emergency exemption label in Colorado for volunteer potato control and could be a useful tool for Washington growers, he said.

The question is whether the onion tolerance is adequate. Boydston is currently collecting yield data from each treatment. The onions will be size graded and the results announced later.

The researcher also told the group that mustard seed (Sinapis alba) meal is being tested for weed control and onion tolerance in an organic onion fi eld. Mustard seed meal is a by-product of mustard oil production. It contains glucosinolates that release isothiocyanates and ionic thiocyanates during decomposition in the soil. These compounds kill small, germinating weed seedlings.

“Mustard seed meal spread on the soil surface at 1 ton/acre or more followed by watering greatly reduced the number of weeds for several weeks after application, but also caused some slight injury to onions when applied at the 2- and 3-leaf stage,” Boydston said.

Canola seed meal also is being tested, but does not appear as promising for weed control, Boydston said, reminding growers that many of the herbicides mentioned above and mustard seed meal are not registered for weed control in onions and cannot be legally used yet.

Seed Corn Maggot Studies
Doug Walsh updated growers on a 2007 onion entomology research project at Mercer Canyons looking at seed treatments for seed corn maggot control. Maggot pressure was “extremely high” at the experimental site.

Walsh is an environmental and agrichemical education specialist at the IAREC, Prosser.

“There were significant differences among the companies that treated seed with Entrust (spinosad),” he observed. “In pairwise t-tests, the seed treated with sponosad by Incotec, Nunhems and Seminis had
signifi cantly greater stand counts than the untreated seed from Incotec.

“There were significant differences among the companies that treated seed with Mundial (fi pronil). In pairwise t-tests, the seed treated with fi pronil by Incotec resulted in significantly greater stand counts than the untreated seed from Incotec.

“There were signifi cant differences among the companies that treated seed with Poncho (clothianidin). In pairwise t-tests, the seed treated with chothianidin by Incotec, Nunhems and Seteco resulted in
signifi cantly greater stand counts than the untreated seed from Incotec.

“There also were significant differences among the over-the-top drench insecticide treatments,” he continued. “In pairwise 5-tests, the plots treated with Lorsban 4E (chlorpyrifos) resulted in significantly greater stand counts than the untreated plots.”

Walsh explained that the results demonstrate that seeds treated with the insecticides spinosad, fipronil and clothianidin can provide signifi cant protection of onion seeds compared to untreated seeds and equivalent control to broadcast applications of chlorpyrifos.

“Spinosad has a federal tolerance on onions, and it is likely that seed treatments will be added as a registered use,” he said. “Bayer … is pursuing registration of clothianidin on onion as a seed treatment, and this use may become available in the future.

Walsh also is looking at onion thrips control in dry bulb onions. The results of that study will be presented Nov. 13 during the 2007 Pacifi c Northwest Vegetable Association Annual Meeting.

Enterobacter Rot Studies
Brenda Schroeder delivered a brief update on work she and Lindsey du Toit are doing on enterobacter rot. An emerging disease causing onion bulb decay, they hope to identify the conditions that promote the disease on storage onions in Washington state. Schroeder is an assistant professor in the Department of Plant Pathology, WSU, Pullman. Caused by the bacterium, Enterobacter cloaca, signifi cant losses from the disease occurred during the 2004-05 storage season, Schroeder said.

The disease develops during storage and affects mature bulbs. Tissues decay, causing the inner scales to turn brown. The rot begins near the neck of the bulb and spreads down each scale individually. Warm late-season fi eld temperatures, in particular, are thought to increase the disease incidence in storage, the researcher said.

Analyses of variance showed no significant effect of curing temperature after harvest on the incidence of bulbs with bacterial rot symptoms, Schroeder announced. This was true regardless of whether the bulbs were harvested from severe, moderate or healthy areas of the field.

That said, “given the diversity of bacterial strains isolated from the symptomatic bulbs in storage, these results do not demonstrate whether or not curing temperature might specifi cally affected the incidence of Enterobacter bulb rot in storage,” the researcher said. Additional research is needed.

Northern Colorado Onion Variety Field Day Held
The Northern Colorado Onion Variety Field Day was held Aug. 29 with visits to two trial sites: Sakata Farms, near Fort Lupton, and Winter Farms, near Eaton.

The field day included a free breakfast and trial status update and an opportunity to check out 49 onion cultivars and lines from nine seed companies. Visitors also were updated on the Iris yellow spot virus situation.

The trials were under the direction of Thaddeus Gourd, Sharon Moore and Tom McBride, all with the Colorado State University Cooperative Extension.

Nunhems Field Day Draws Impressive Crowd
Nearly 200, the majority onion growers and seed company representatives, were on hand for the 2007 Nunhems Onion Field Day, held Aug. 22 at Story Farms, near Parma, Idaho.

What made the turnout even more impressive is that a separate showing for Nunhems employees was held the date before, noted Rick Watson, Nunhems onion breeder. The majority of those checking over the plots were actual growers. Spotlighted this year were demonstration plots of Joaquin, Arcero and Grand Coulee, three new yellow Spanish-type onion introductions.

Joaquin: A “very late” standing, vigorous and disease-tolerant variety, Joaquin has performed exceptionally well over the past couple of years, especially under heat, thrips and Iris yellow spot virus pressure, Watson observed. Because of that, there is considerable grower interest.

The name Joaquin comes from California’s San Joaquin Valley, where the variety is well suited for the late-harvest time frame, the plant breeder said. Joaquin is later maturing than most varieties grown in the Treasure Valley, but in recent trials has performed exceptionally well.

Joaquin is a high quality onion with good single centers and great potential for processing, Watson observed. It also has good store ability. To take advantage of Joaquin’s stress tolerance, yielding ability and long storage performance, growers will need to learn how to best manage this “very late” standing variety. Seed supplies for the 2008 production season will be limited.

Arcero: The second new variety included during the tour, Arcero is another yellow, full Spanish-type onion. It has strong scale adherence and long storage ability, Watson said. It also produces a high
percentage of single centers and, hence, is a good alternative for processing. One of its unique attributes is the whiteness of its after coming out of several months of storage.

Arcero does well in the Treasure Valley and California, Watson said. It is a full-season variety, but its maturity (around 120 days) is more in line with traditional varieties grown in the Treasure Valley.

“Arcero is a quality onion, has high solids and performs very well,” Watson said, cautioning, however, that it is not the choice for those after super colossal sizes. Its dark, bright scales, however, give in an attractive appearance in consumer packs.”

Because Arcero is in its second full year of commercial release, seed will be available for the 2008 season.

Grand Coulee: The third new introduction highlighted, Grand Coulee is a westernexport type onion with strong, dark scales and high solids. It is especially adapted for mechanical handling and long storage, stores well in bulk and meets the needs of export markets, Watson said.

“Grand Coulee is well adapted for use in the Columbia Basin of Washington as well as here in the Treasure Valley,” the Nunhems onion breeder said. “It produces high quality onions that are ideal for the export market.”

While classified as a Spanish-type onion, Grand Coulee also has some non-Spanish blood, Watson pointed out. Its high solids and early maturity help it produce highquality, long storing bulbs; but these same traits make it less able to produce large sized bulbs under extreme heat in the way that Arcero and especially Joaquin can.

Global Genetics Highlights Maverick and Ringleader
Fifty Treasure Valley onion growers attended the Global Genetics Annual Field Day, held Aug. 20 at Ron Mio Farms, Fruitland, Idaho. On display were commercial plantings of Maverick, a 122-day yellow Spanish onion know for its high yields and colossal sizes, and Ringleader, a 120-day Spanish onion that produces an exceptionally high percentage of single centers.

Plant breeder Dean Medler also displayed several experimental items from his breeder trials slated for advancement to commercial status over the next few years. Included are red, white and storage types.

Representatives from Scottseed and Keithly Williams were on hand to give tours through the trial plots. Lunch was served by Matsy’s of Ontario, Ore.

“Growers have shown a lot of interest in Maverick and Ringleader over the last couple of years,” Medler said, adding that Global Genetics is working hard on developing onions for other market segments as well.

Founded in 1998, Global Genetics is a Payette, Idaho-based onion breeding and seed production company.

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