By Angela Dansby
U.S. and Canadian researchers discussed their findings on diseases, integrated pest management, pollinators, climate-smart agriculture, agronomy, plant breeding and genetics related to spring and/or winter canola at the 2023 National Canola Research Conference (NCRC) Oct. 30-31 in St. Louis. Normally held every four years in conjunction with the American Society of Agronomy meetings, the last NCRC was in 2018 and delayed a year due to COVID-19. Here is a snapshot of reported findings by category.
Clubroot — a soil-borne canola disease that attacks roots, forming “clubs” or galls, and severely reduces crop yield and quality — was first discovered near Edmonton, Alberta in 2003, said Stephen Strelkov, professor of plant pathology at the University of Alberta. Today, clubroot is found in about two-thirds of Alberta fields where the disease exists, spread by machinery and dust. While rotating the crop and sanitizing machinery helps manage the disease, clubroot-resistant varieties are the best defense. As of 2022, 72 percent of Canadian canola acres were planted to these varieties (60 now available). The challenge is to stay on top of rapidly developing disease types that can overcome resistance and to harmonize labeling for resistant varieties. More at clubroot.ca by the Canola Council of Canada.
Blackleg has been in Canadian canola for 40-45 years and now it’s a major issue both in Canada and the United States that can affect all plant parts, not just stems, said Dilantha Fernando, professor and dean of the University of Manitoba’s Department of Plant Science. Only four major resistance genes are currently available and not all work well together. Moreover, since 2010, blackleg-resistant canola varieties have been susceptible to breakdown. These varieties may need support from fungicide-treated seed to make it to seedling stage.
Timothy Paulitz, research plant pathologist in Washington State University’s Department of Crop and Soil Sciences, noted that including canola has a number of rotation benefits, including improving soil structure, breaking disease cycles and providing better options for weed control. However, it has both positive and negative effects on microbial communities on wheat roots in the Pacific Northwest. Research suggests that winter wheat followed by spring canola is better than the opposite.
Breeding crops like canola with larger and deeper roots can enable more carbon dioxide (CO2) storage in soil to combat climate change, noted Todd Michael, research professor at the Salk Institute for Biological Studies. “Plants are the primary biomass and source of carbon storage on earth. We should harness that to reduce climate change.” He and fellow researchers are using machine learning to predict how much CO2 roots can store based on their shapes and sizes.
Principal Economist Steffen Mueller of the University of Illinois-Chicago’s Energy Resources Center examined lifecycle greenhouse gas emissions of canola oil-based biofuels and induced Land Use Change (iLUC) implications under different regulatory schemes. He noted that iLUC is critical in determining carbon intensity (CI) scores and “each CI point is worth money.” The carbon-storing ability of plant roots should be factored into lifecycle analyses in spite of uncertainty regarding the permanence and measurability of carbon sequestration, Mueller added. CORSIA by the International Civil Aviation Association, which offers sustainability certification for sustainable aviation fuel, is likely to accept data about plant roots and carbon.
AGRONOMY: SPRING CANOLA
Extension Soil Scientist Don Wysocki of Oregon State University looked at seed mixes and optimum sowing rates, discovering that canola and peas planted together are mutually beneficial. Speculative reasons why include better weed control, nitrogen sharing and soil water use. Peas use upper soil water, while canola takes advantage of deeper soil water.
“Flea beetles are the most destructive insect pest in canola,” said Dave Grafstrom, professor of agronomy and plant genetics at the University of Minnesota, as they cost an average of $300 million per year in North America to control. There is a correlation between plant vigor and yield, and flea beetles affect both. He noted that seed treatments often cannot control them alone so foliar treatments must also be used.
Research Associate Mark Thorne of Washington State University’s Dept. of Crop and Soil Sciences, noted that Italian Ryegrass is the most challenging weed for canola in the Pacific Northwest, especially because it has developed resistance to some Group 9 and 10 herbicides like glyphosate and glufosinate. Fortunately, Group 3 herbicides are still effective. Farmers should rotate herbicide groups with different modes of action to help prevent resistance.
The four major canola diseases – blackleg, sclerotinia, clubroot and Verticillum stripe in order of frequency – can cause seed lodging along with plant damage, noted Venkata Chapara, assistant research professor at North Dakota State University’s Langdon Research Extension Center. Blackleg can can cause an upper canopy infection in addition to typical stem cankers, he warned. Clubroot, first identified in North Dakota in 2013, cannot be controlled with pesticides so prevention with the use of resistant varieties is critical. V. stripe is new in the state, yet already found in seven of 11 canola counties in 2022. It is hard to distinguish from blackleg because it also causes stem cankers near roots but they tend to be brown instead of black.
AGRONOMY: CROSSOVER TOPICS
Quigwu Xue, associate professor of crop stress physiology at Texas A&M AgriLife Research and Extension Center, evaluated the salinity stress of canola cultivars in the Rio Grande Valley region of Texas and New Mexico. That area tends to have saline soil and limited water. Findings from two years of greenhouse studies indicated that there is a genetic potential to improve salt tolerance.
Rajan Shrestha, post-doctoral research associate at Texas A&M AgriLife Research, also evaluated canola cultivars in the Rio Grande Valley under irrigated saline water for salt tolerance. He noted that 7 percent of global arable land is affected by salinity, accounting for millions of hectares. Stem mass and photosynthesis rate were used to identify salt-tolerant genes.
Research Scientist Chad Koscielny of Corteva Agriscience discussed a forecasting model for canola seed composition, noting that higher growing temperatures decrease oil and increase protein content. His model is quite accurate except in the case of extreme weather conditions. He aims to create a publicly available, scalable model for predicting composition.
Josh Lofton, assistant professor of plant and soil sciences at Oklahoma State University, reported on experiments with nitrogen (N) applications in winter canola. He found that putting a lot of N up front led to excessive growth and winter kill, reducing yields the following spring. He recommends applying most N at the “green up” or bolting stage for more moderate growth initially and higher yields on the back end. Overall, yields were significantly higher when N applications were split between a winter and spring application (10-27% increase). The application of N at planting was never beneficial in comparison.
PLANT BREEDING & GENETICS
Research Plant Physiologist Zahirul Talukder of the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) looked at freezing tolerance of winter canola via gene editing. He found that a specific gene plays a role in this tolerance.
Research Chemist James Anderson of the USDA-ARS presented the results of field trials on winter-hardy winter canola, which “has cash cover crop potential.” The top three of 10 evaluated will be advanced in breeding programs.
David Horvath, research plant physiologist at the USDA-ARS, noted that winter canola acquires increased freezing tolerance if first acclimated to low, non-freezing temperatures. However, if cold-acclimated plants are exposed to warmer temperatures for several days, they lose freezing tolerance in a process called deacclimation. Due to global warming, these scenarios will likely become frequent so Horvath and his team looked at genes to see if any would reduce the deacclimation rate in winter canola. Instead they discovered a gene that may increase deacclimation so they will explore the impact of knocking it out via gene editing.
Agronomist Mike Stamm of Kansas State University discussed the development of winter canola hybrids for the Great Plains that have improved yield and oil content over open-pollinated varieties. Results from multiple hybrid trials in Kansas and New Mexico over two growing seasons show that their winter survival rate was also very good.
Kurt Schroeder, associate professor of plant sciences at the University of Idaho-Moscow, discussed canola breeding efforts to increase blackleg resistance in the Pacific Northwest. He said good genes were identified to create resistant varities, which are urgently needed because the disease is now endemic in the rain-fed areas of eastern Washington and northern Idaho. Blackleg arrived in the region 15 years ago and spreads rapidly not only in canola but also in nearby weeds and cover crops.
Genomic predictions in canola can be made with the use of machine learning and artificial intelligence via robots and drones, reported Mukhlesur Rahman, canola breeder at North Dakota State University. Robots can move through fields to count stands and measure stem diameters. (They can also apply pesticides.) Drones are used for phenotyping to determine pod shatter tolerance. Rahman conducted his research in collaboration with CCAST, a super computing center in N. Dakota.
Jakir Hasan, research assistant professor for small grains crops breeding at the University of Alaska, identified clubroot resistance genes in spring canola to help create new varieties.
Clubroot disease causes 10-15 percent yield loss in Brassica crops worldwide, including canola and a range of vegetables, according to Masud Karim, research biologist at Agriculture & Agri-Food Canada. The disease has been reported in more than 60 countries. It was first discovered in Canada (Alberta) in 2003 and as of 2021, it has 30 pathotypes spread across all three Canadian prairie provinces (Alberta, Manitoba and Saskatchewan). “It’s a race for scientists to fight against a pathotype,” Karim said. That’s why Karim is developing clubroot-resistant canola varieties.
Robert Duncan, assistant professor and Brassica breeder at the University of Manitoba, conducted one of only “a few studies to have documented response mechanisms to drought stress.” Using hydroponic trials, he induced stress in canola plants to find tolerant genes.
Mohammed Mira, associate professor at the University of Manitoba, found that phytoglobins, types of plant protein, can improve drought and heat tolerance in canola by scavenging nitrous oxide. He also figured out pathways for both benefits and found that phytoglobins can be used to predict plant response to stress. By manipulating phytoglobins, canola plants can become more tolerant to heat and drought. His findings were published in the Annals of Botany on Dec. 26, 2022.
Pod shatter tolerance in canola is influenced by both genetics and weather conditions, reported Lauren Gislason, graduate student at the University of Manitoba. But dessication is also a factor that needs to be studied. Pod shattering reduces yield and revenue through seed loss, while dropped seeds become competitive weeds in future seasons. She identified genomic regions and molecular markers to help canola breeders select genes with improved pod shatter tolerance.
Rajeev Dhakal, graduate student at the University of Saskatchewan, said that canola requires a significant amount of nitrogen (N) fertilizer. That’s because less than 50% of applied fertilizer N is recovered as seed N. Dhakal discovered that higher soil moisture allowed for higher N and nitrogen use efficiency in spring canola. Also, the crop uses N more efficiently when it’s in deficit rather than abundance. This information could be used to improve nitrogen use efficiency.
Many thanks to Mike Stamm of Kansas State University for organizing the conference and to these sponsors for enabling it to happen: Bayer CropScience, BASF, Bunge, CHS Inc., NuSeed, Rubisco Seeds, Syngenta and the U.S. Canola Association.
Angela Dansby is director of communications for the U.S. Canola Association.