NDSU barley screening nursery under mist irrigation at Osnabrock.
NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
August 5, 1999
Situated near the communities of Osnabrock, Langdon and Amenia are some of the research plots operated by the North Dakota Agricultural Experiment Station and the North Dakota State University Extension Service. Since the mid-1990s, these plots have handled a specific assignment in the battle against Fusarium head blight (FHB or scab), a fungal disease that has plagued small grain crops throughout much of the region for most of the decade.
These NDSU plots have become screening nurseries that researchers have equipped with mist-irrigation systems to create uniform, epidemic-level disease conditions for evaluating scab resistance in small grains. Initially, funding for scab research came from sources such as the North Dakota Legislature, state commodity groups in North Dakota and Minnesota, county crop improvement associations, and the American Malting Barley Association.
Now, federal funding linked to the U.S. Wheat and Barley Scab Initiative is making it possible to bring a part of the world to North Dakota.
Barley
"This year we began screening the USDA's world collection of spring six-rowed barley accessions (germ plasm material)," says Rich Horsley, NDSU's six-rowed barley breeder. "We're evaluating about 4,200 entries this year and will screen the remainder next year. This is something we wanted to do in the past but never had the funding to make it a top priority."
Since 1998, USDA has earmarked about $3.5 million from the budget of the Agricultural Research Service to fund scab research, says Horsley, a member of the eight-person executive committee for the U.S. Wheat and Barley Scab Initiative. Among its duties, the committee makes recommendations to USDA-ARS regarding research focus and funding levels.
NDSU's share of 1999 federal dollars totaled about $833,000. Nationally, about 110 scab research projects received federal funding; slightly less than one-fifth of those ongoing projects are being directed by NDSU researchers. Research funded by the U.S. Wheat and Barley Scab Initiative focuses on six areas: variety development, germ plasm introduction, chemical and biological control, epidemiology and disease management, toxicology and utilization, and biotechnology.
Horsley says the federal dollars dedicated to screening the world collection of spring six-rowed accessions have allowed NDSU to increase the size of its Osnabrock nursery by 60 percent and to automate the mist-irrigation system at Langdon. Other federal funds devoted to scab-related research for barley breeding, pathology and quality evaluation are being pooled by NDSU's six-rowed and two-rowed barley development teams. Jerry Franckowiak is NDSU's two-rowed barley breeder.
"In general, two-rowed barleys exhibit much lower scab and mycotoxin levels than six-rowed barleys," says Brian Steffenson, an NDSU plant pathologist who specializes in diseases affecting barley. "NDSU has released several outstanding two-rowed varieties with good malt-quality profiles. However, it remains to be seen whether these varieties will be accepted by industry for malting and brewing. For malting barley producers, these varieties could possibly serve as a short-term solution to the scab problem until scab-resistant six-rowed varieties are developed."
Along with the mist-irrigation systems, the barley screening nurseries at Osnabrock and Langdon are teeming with scab inoculum--in the form of sterilized barley and corn seeds infested with the scab fungus. (The barley and corn seeds' germs have been killed by excessive heat.) Researchers grow the scab fungus in the lab, mix it with the sterilized corn and barley seeds and then spread the material on the ground throughout the screening nurseries, Horsley explains. Because much of the material growing in the nurseries is susceptible to scab, many of the plants in this disease-rich environment become infected and die.
"This is a technique Brian (Steffenson) and Jerry Franckowiak learned from our cooperative work in China," Horsley says. "The overall effort devoted to scab research involves universities, private companies, government scientists, commodity groups and individuals from around the world."
Last year, Busch Agricultural Resources Inc. screened the world collection of spring six-rowed accessions, Horsley says, but that screening was carried out under natural field conditions without the benefit of mist irrigation. From that effort, Busch researchers identified about 100 experimental lines exhibiting potential scab resistance. Horsley and Steffenson are evaluating those lines this year in replicated trials at the Osnabrock and Langdon sites. In addition, they continue to evaluate elite material generated within the NDSU six-rowed barley program. All the material is being grown under mist irrigation.
Hard Red Spring Wheat
The mist-irrigation systems in use at NDSU were designed by the hard red spring wheat plant breeding team in 1995. Nozzle type and configuration are what make this design different from others in use at other research universities, says Richard Frohberg, NDSU's hard red spring wheat breeder.
"We wanted to get a small droplet size," Frohberg explains. "You don't want to wash the spores off the head."
Canadian research has shown that most scab spores are ejected in the evening, and air currents carry them to wheat spikes, Frohberg says. For that reason, the automated mist-irrigation systems run at only seconds-long intervals for three consecutive nights, beginning at midnight. The free water from the mist-irrigation systems provide the dew-like moisture for spores to germinate and infect.
The three-night misting sequence corresponds to the flowering period for wheat--the stage when it is most susceptible to scab infection. Those three-nights-on-four-nights-off cycles are repeated for three weeks to account for the differing maturities of the experimental lines under evaluation.
"Usually, three weeks covers all the genotypes," Frohberg says. "Of course, genotypes that head early are subjected to a more severe test under this three-week regimen."
Three weeks after flowering, researchers harvest a portion of the replicated material and freeze it so they can thoroughly evaluate scab severity after the growing season has ended. Meanwhile, they conduct an in-field severity evaluation with the remaining replicated material, which then matures normally, and when harvested, the researchers evaluate yield, vomitoxin (deoxynivalenol or DON) levels and other quality factors. Working with Frohberg in this area of research is Robert Stack, an NDSU plant pathologist specializing in wheat diseases.
Frohberg reports that two NDSU hard red spring wheat lines possessing enhanced tolerance to scab and containing the other attributes needed for commercial production are in advanced stages of development. Meanwhile, additional screening continues.
"We've evaluated germ plasm from Hungary and Brazil and have access to germ plasm from countries such as China," Frohberg says.
For hard red spring wheat, the world collection of germ plasm is being evaluated at South Dakota State University. USDA researchers are also studying wild relatives of wheat and related grasses. Frohberg says the Uniform Regional Scab Nursery was set up in 1995 for cooperative evaluation of material that might make promising parents; there are six locations in Minnesota, the Dakotas and Manitoba. In North Dakota, the nurseries are included among the NDSU research plots near Langdon and Amenia.
Durum
In 1998, the NDSU research plots near Amenia also included a nursery to screen a portion of the world collection of durum accessions, but the plants were overcome with other wheat leaf diseases before scab had a chance to develop, says Elias Elias, NDSU's durum breeder. As part of his role with the U.S. Wheat and Barley Scab Initiative, Elias is responsible for screening this collection, the evaluation of which is now being staged in China and France. In China Elias is coordinating the project with a government agency, and in France he is working with a private seed company, Groupment Agricole Essonnois (GAE).
"Worldwide, there are about 6,000 accessions for durum that need to be screened," Elias says. "Our goal is to screen about 2,000 a year, which means we should conclude in the year 2001."
Like NDSU's barley and hard red spring wheat programs, the durum program also relies on mist-irrigation systems to create a uniform disease environment for the experimental lines under development, Elias says. In his replicated plots near Amenia this year, Elias is growing out about 3,000 experimental lines, crosses of experimental lines and crosses with wild material. Next year, he plans to evaluate between 3,000 and 4,000 lines.
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Sources: Richard Horsley (701) 231-8142
Brian Steffenson (701) 231-7078
Richard Frohberg (701) 231-8143
Elias Elias (701) 231-8159
Editor: Dean Hulse (701) 231-6136
NDSU barley screening nursery under mist irrigation at Osnabrock.
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