How Research Works
A Case Study: Disease Resistance in Small Grains
Agricultural research, be it current or historic, molecular or applied, meets pressing needs of Minnesotans. While many successes are documented here, a look at an ongoing project illustrates the complexity of agriculture and research.
Fusarium headblight, commonly known as "scab", is a disease affecting wheat and barley that emerged in 1993. By 1995 the outbreak became an epidemic and by 2000 had caused $1 billion of crop losses in Minnesota and the Dakotas. The Minnesota Legislature responded by funding a research effort of over a million dollars a year. In the last century, no plant disease in this region has caused so much damage, though rust outbreaks from 1900-30s came close.
Researchers found that the scab devastation was caused by a convergence of a number of factors.
- Wheat and barley varieties used did not have resistance to scab.
- Increased popularity of reduced tillage, leaving more surface residue which reduces erosion, but also harbors the pathogen.
- New crops — some host fusarium — were grown in the small grain areas as farmers diversified.
- Rotten weather, specifically, more than usual warm-moist conditions during grain heading that provided ideal conditions for fungal growth.
U of M and USDA geneticists had previously identified some resistance in Chinese varieties. However, as the timeline below shows, it takes almost a decade to release a new variety. Gene splicing allows more precise control over the results, but a genetic source of resistance must first be identified.
Besides breeding efforts, fusarium headblight is being fought on other fronts. Plant pathologists developed techniques to more rapidly test for the disease. Agricultural engineers invented processes to separate infected kernels from clean ones, providing hope that producers would still be able to market their crop. Food scientists and livestock researchers test consumer acceptance of food, feed, and beverages that contain residual levels of scab.
While the fight to control fusarium headblight is not over, new varieties represent incremental improvements. Other spin offs from this effort will help when future challenges arise: techniques to measure traces of disease, and new nurseries, irrigation systems, and greenhouses that will be used far into the future.
Plant Breeding Timeline: A Decade of Commitment
|Year 0||Initial cross-pollination of parents, one may include a gene spliced from another source. Many crosses (up to 200) of these parents are made to ensure an adequate seed supply for future tests.|
|Year 1||Three consecutive generations of self-pollinated plants are grown, to ensure uniform genetic backgrounds. (1) greenhouse (1 seed per pot, about 1,000 pots); (2) field (800 plants per cross); (3) greenhouse (random selection from 200 field plants, 1 seed taken from each)|
|Year 2||Seed (4th generation) is increased in winter nursery (Arizona) from 200 plants. Spring planting (5th generation) in 6 foot rows at St. Paul and Crookston, 20 best performing lines are identified. Initial, small scale malting test is conducted.|
|Year 3||Seeds from 20 best are grown in Arizona to obtain 2 pounds of seed (6th generation) from each. Preliminary yield tests (7th generation) are grown in St. Paul and Crookston: 2 rows, each 10 feet long, replicated 3 times. Highest yielding lines move on.|
|Year 4||Advanced yield trials in 5 Minnesota locations. Plots are 10 rows, each 10 feet long, with 3 replications.|
|Year 5||1st year of regional tests, 8-10 locations in Manitoba, North Dakota, and Wisonsin. Very competitive. 1st year of pilot plant malting tests, using a few pounds of seed.|
|Year 6||2nd year of regional performance tests and pilot plant malting. Variety release process begins with a seed increase program designed to supply expected grower demand.|
|Year 7||Seed increase continues. Large scale malting and brewing evaluations by American Malting Barley Association, using minimum of 2,500 bushels.|
|Year 8||New variety officially named and released by U of M Agricultural Experiment Station. Year of release is listed in this publication|
|Year 9||Seed widely available to growers through seed companies|
U of M Agricultural Research Sites
For well over a century the University of Minnesota Agricultural Experiment Station has developed plants that provide food for life. Minnesota crops feed livestock and the citizens of Minnesota, the United States, and literally the world. Potential new crops, and improved varieties and germplasm of those already established, begin their testing on the St. Paul Campus. Potential releases are tested at Research and Outreach Centers and other research facilities, which represent the wide range of moisture, soil, and temperature conditions found in Minnesota. If a variety is chosen for release it is usually marketed through the Minnesota Crop Improvement Association, or germplasm is provided to commercial seed companies that use it to adapt their varieties to Minnesota conditions.
Progress Against Scab
- BacUp, wheat, 1996, reasonable yield and kernel quality even in scab conditions, introduced as a "bridge" to farmers in areas with severe scab conditions until more resistant varieties are developed.
- HJ98, wheat, 1998, high yield wheat, medium protein, medium-high scab resistance.
- McVEY, wheat, 1999, first wheat variety with very high yield under either scab or no-scab conditions.
- MnBRITE, barley, 1998, malting variety with some resistance to fusarium head-blight.
- LACEY, barley, 2000, moderately scab-resistant malting barley.