- Author: Jeannette E. Warnert
Aflatoxin can form on a wide variety of crops, from corn to cotton to tree nuts. Careful management practices help keep levels low, but still hundreds of thousands of pounds of pistachios are rejected each year due to the presence of aflatoxin.
UC Davis plant pathologist Themis Michailides and his team of researchers at Kearney discovered how to expose pistachio trees to the spores of a beneficial fungus that displaces the fungi that produce aflatoxin. Displacing aflatoxigenic fungi with a beneficial fungus has never before been done in tree crops.
“We’ve gotten great results,” Michailides said. “The reduction in aflatoxin contaminated nuts has been up to 45 percent. We anticipate higher reduction with application of the beneficial fungus for multiple years and on larger acreage.”
The new process was approved by the U.S. Environmental Protection Agency in February and the California Department of Pesticide Regulation in May, in time for 60,000 acres of the 2012 California pistachio crop to receive the innovative treatment.
“This is a big step,” Michailides said. “There will be a tremendous savings to pistachio growers by reducing rejections and the need for resorting nuts before going to market.”
Aflatoxin was discovered in the 1960s when a flock of turkeys in England died after eating contaminated feed. Aflatoxin is produced by certain strains of the fungus Aspergillus flavus, which is commonly found in soil and decaying vegetation. Aflatoxin is a resilient foe. Roasting nuts does not destroy the toxin. Other crops, such as corn and cottonseed used as animal feed, can be treated with ammonia to reduce aflatoxin, however ammonia treatment is not possible for human food, such as tree nut crops.
All shipments of pistachios are tested for aflatoxins, and are rejected in Europe if contamination exceeds 10 parts per billion and in the United States if shipments have more than 15 parts per billion.
The use of beneficial fungi to fight aflatoxin was first discovered and investigated by Peter Cotty, a USDA Agricultural Research Service plant pathologist located in the School of Plant Sciences at the University of Arizona. Cotty’s research focuses on reducing aflatoxin presence in corn and cottonseed. In collaboration with Cotty, Michailides and his colleague Mark Doster, staff research associate in the Michailides lab at Kearney, found that Aspergillus flavus 36 (AF36) can be introduced into an orchard by inoculating “dead” wheat seeds and then dispersing the seeds on the orchard floor. Dew and soil moisture spur the development of harmless spores that colonize pistachios and prevent colonization by toxigenic fungus strains.
The Kearney scientists are continuing their cooperation with USDA’s Cotty as they expand the research to almonds and figs.
“We’re conducting micro-plot experiments with the almond industry at Kearney,” Michailides. “We hope to get an experimental use permit soon to make the treatment available to almond growers.”
Michailides’ aflatoxin research was funded by USDA, the California Pistachio Research Board, the Almond Board of California and a UC Discovery Grant. The research was made possible by the involvement of cooperating pistachio growers who opened their orchards to scientists for conducting AF36 trials.
- Author: Jeannette E. Warnert
Among the conditions necessary for a cow to produce organic milk, she must eat only organic feed or browse on organic pasture for at least the previous 36 months. However, dairy producers have found that producing or sourcing organic feed – which must be grown with no synthetic fertilizers, insecticides or herbicides – is challenging. Recently organic alfalfa made up nearly 1.4 percent of U.S. alfalfa hay production, up from .5 percent in the early 2000s.
Dan Putnam, UC Cooperative Extension specialist in the Department of Plant Sciences at UC Davis, an alfalfa expert, said one key obstacle for organic alfalfa producers is weed management. Putnam put together a team of alfalfa hay experts to conduct an alfalfa weed management trial at the UC Kearney Agricultural Research and Extension Center, where 10 acres are set aside to research organic production.
In 2011, Putnam; Carol Frate, UCCE advisor in Tulare County; and Shannon Mueller, UCCE advisor in Fresno County, experimented with timing seeding and early clipping to manage organic alfalfa in a weedy field.
“Alfalfa can be planted from early September all the way through the fall and winter to early spring, depending on weather patterns,” Putnam said. “Many farmers plant in late November and wait for rain to bring the crop up. Other options are irrigating the crop up in early fall or waiting till early or late spring to plant the crop. All of these strategies have implications for weed management.”
The late November planting is quite common since, compared to a September planting, it saves farmers the trouble of putting out sprinklers. However, late fall plantings failed in this experiment.
“We had a lot of weed intrusion at that point as well as cold conditions for alfalfa growth, so the stands were poor,” Putnam said.
The earlier planting also had weed intrusion, but the researchers clipped the field when the alfalfa was 10 to 12 inches high in early spring. The clipping cut back weeds that were overtopping the alfalfa, giving an advantage to the vigorous young alfalfa seedlings.
An early spring planting after tillage to destroy weeds also resulted in a good stand, but some production was lost in the first year compared with early fall plantings.
“Many growers are starting to realize that early fall (September/October) is a better time to start their alfalfa crops,” Putnam said. “With organic growers, it is even more important to pay attention to time of seeding because they have so few weed control options.”
While this research is conducted on organic alfalfa, Putnam said the results are also applicable to conventional alfalfa production, which represents more than 98 percent of California's total alfalfa crop.
“Timing has a profound effect on the first-year yield and health of the crop and its ability to compete with weeds,” he said.
Putnam, Mueller and Frate will share more information about the organic alfalfa trial during a field day at Kearney, 9240 S. Riverband Ave., Parlier, from 8 a.m. to 12 noon Sept. 5. The field day will feature the organic production trials, alfalfa variety trials, sorghum silage and nitrogen trials, and optimizing small grain yields. Other topics will be alfalfa pest management, irrigation and stand establishment.
- Author: Jeannette E. Warnert
If a superb winegrape cultivar adapted to warm temperatures emerges from a research trial at the UC Kearney Agricultural Research and Extension Center, the state’s premiere agricultural region may be able to establish a reputation for growing fine wines.
For this reason, UC Cooperative Extension specialists in the Department of Viticulture and Enology at UC Davis have teamed up with winemakers from Constellation Brands to identify a wine variety that excites the palette and flourishes in the San Joaquin Valley’s hot climate.
At the outset, the researchers were searching for blending varieties that would make San Joaquin Valley wines with familiar names more interesting. Vintners may use up to 25 percent of the grape volume to impart distinctive color, flavor, and structure to a varietal wine without calling it a blend. The winegrapes being studied at Kearney, the researchers believed, could add a certain flavor note or deep color to a San Joaquin Valley Merlot, Cabernet Sauvignon, or Chardonnay.
Moreover, changing demographics may present opportunities for new varietal wines, especially for the newest generation of potential wine drinkers, the generation known as “millennials,” only about half of whom have turned 21.
“We have a group of wine consumers coming through who are more accepting of different varieties than their parents were,” says James Wolpert, UC Cooperative Extension specialist in the Department of Viticulture & Enology at UC Davis. “We are poised to have a real renaissance in the wine business.”
Currently, 80 percent of California wine is made from fewer than 10 types of winegrapes. Most of the popular wine varieties in California – among them merlot, cabernet sauvignon and chardonnay – are at their best in somewhat cooler climates. The researchers are looking for grapes that make superior fruit in warm climates.
“You wouldn’t plant a palm tree in Michigan. So why would you plant merlot in the desert?” asks Oren Kaye, a research and development winemaker at Constellation Brands. “The San Joaquin Valley has never established itself as a ‘destination’ wine region because we have always been chasing the wrong grapes.”
The unsuitability of California’s most popular winegrape cultivars to the Central Valley’s climate is reflected clearly in industry statistics. The San Joaquin Valley is California’s largest grape growing district in terms of production, but lowest in terms of price. According to the California Department of Food and Agriculture 2011 Grape Crush Report, District 13 – which includes the counties of Madera, Fresno, Alpine, Mono, and Inyo; and parts of Kings and Tulare counties – had the largest share of the state’s crush, at 1,495,027 tons. District 13’s average price per ton in 2011 was $324.26. In contrast, the value of the crush in District 4 – Napa County – was $3,258.88 per ton.
Matthew Fidelibus, UC Cooperative Extension specialist in the Department of Viticulture and Enology at UC Davis, attributes the 10-fold price differential in part to the impact of weather on particular winegrape varieties. In grape varieties adapted to a cooler climate, some biological pathways are stifled at elevated temperatures. As a result, some important flavor compounds develop out of sync with sugar accumulation, and the grapes may not attain their potential flavor peak before it is time to harvest.
Anthocyanins, for example, give red wines their characteristic deep scarlet to purple color, but high temperatures suppress anthocyanin accumulation in some varieties.
“We would like to identify a winegrape in which anthocyanins accumulate at higher levels in San Joaquin Valley,” Fidelibus says. “We have no problem getting enough sugar in the grapes. But other desirable compounds may be deficient.”
To find new varieties suitable for warm, dry weather, the scientists turned to Foundation Plant Services (FPS) at UC Davis, which manages the National Grapevine Importation Program, the largest program for importing grape selections into the U.S.
FPS enables grape growers, nurseries, researchers, and wineries to bring valuable new selections into the U.S. without the threat of importing foreign exotic pests and diseases that could cause serious damage to the industry. From 1995 through 2006, over 640 new selections were imported.
Wolpert, the Kearney project’s initial principal investigator, selected 55 winegrape cultivars from Spain, Greece, Italy, and other areas where the climate is similar to the San Joaquin Valley’s.
It used to take 15 years to bring in new varieties,” Wolpert recalls. “FPS got that down to five. They have stuffed the pipeline full of interesting grapes, some you cannot find on the East Coast (of the U.S.).
The varieties chosen for the project are not exactly “new,” Wolpert clarified. Some are 1,000 years old, but are new to California.
Fidelibus, now the principal investigator on the grape production side, is gathering data on each variety’s yield potential, cluster architecture, amenability to mechanization, and other viticultural characteristics. The research vineyard contains 50 vines of each variety on 1103P rootstock. The rootstock was planted in 2008 and was budded to 55 varieties in spring 2009 with some re-budding in 2010. Vines were trained to bilateral cordons on trellises with a cordon wire 48 inches above the soil surface, and two foliar catch wires on a 10-inch wide cross arm, about 15 inches above the foliage catch wire. Vines were drip-irrigated, at about 60 percent ETc, and spur-pruned with approximately 15 shoots per meter of cordon. They were allowed to retain their entire crop, which ranged from 2.3 to 33 kg of fruit/vine, depending on the variety.
Constellation Brands winemaking personnel are monitoring the winegrapes’ potential to produce distinctive, flavorful California wines. Of the 55 Old World winegrape varieties planted in the 1.4-acre plot at Kearney, about half displayed enough promising characteristics in 2011 to prompt Constellation Brands to make 25 small (10-gallon) lots of wine from 150 to 200 lbs of grapes.
"In 2008, we picked all red varieties at 24o Brix," recalls Kaye. "In 2011, we picked red varieties at 24o Brix and white varieties at 22o Brix."
From the winemakers’ standpoint, the next great California wines will need excellent color, superior mouthfeel, no vegetative characteristics, desirable flavors, and importantly, an elusive quality that marketers call “cachet.” Cachet is a certain, unmeasurable aplomb that confers a special status or prestige on which to build a reputation.
The Kearney wines are on the right track.
"Many of the wines turned out better than we expected," Fidelibus said. "A lot of the reds had very good color, better color than some of the traditional varieties. Some of the whites hadhigh acidity,which is a good quality for the San Joaquin Valley because high temperatures tend to reduce acidity."
At a recent tasting in Fresno, Kaye introduced winegrape growers and industry representatives to four wines made from grapes in the Kearney plot, Fiano, Biancu Gentile, Sagrantino, and Marselan Noir. Even though wine was produced in small lots and the winemaking process was not optimized, the wines have piqued the researchers’ interest.
Fiano is a white wine with a fresh, young style evoking flavors of melon and grapefruit,” Kaye says. Marselan noir is a stylistically unique red wine with bright cherry flavor that pops.
"In our internal tastings, these wines and several others showed some promise, but it is too early to know for sure,” Kaye concludes. "Constellation Wines will vet 20 to 30 varieties again in 2012. Some will be repeats. If we can eliminate half of the varieties that is progress as it will help us focus on the ones with greater potential for the San Joaquin Valley."
Fidelibus comments in the video below about the recent tasting event that featured four winegrape varieties from the Kearney trial:
- Author: Jeannette E. Warnert
Eight long-time UC Kearney Agricultural Research and Extension Center employees - with experience and institutional knowledge from a combined 238 years of service - retired today.
About 100 current and retired Kearney staff and academics gathered in the center's multi-purpose room to see them off. The retirees are:
Walt Bentley, UC Cooperative Extension advisor, Integrated Pest Management entomology, 36 years
Diana Bulls, administrative assistant, 20 years
Sal Garcia, assistant custodial supervisor, 21 years
Kathy Montanez, financial services manager, Business Operations Center - Kearney, 29 years
Lois Strole, administrative assistant, 18 years
Charlie Summers, research entomologist, UC Davis Department of Entomology, 42 years
Two retirees were not able to attend the celebration:
Mike McKenry, UC Cooperative Extension specialist, UC Riverside Department of Nematology, 40 years
Stephanie Kaku, staff research associate, 32 years
- Author: Jeannette E. Warnert
At the behest of the Table Grape Commission, members of the public are visiting Kearney's sensory lab facility today to taste and evaluate grape selections from the USDA's table grape breeding program.
