Wheat research projects you should know about

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Prairie Grains is the
official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain
Growers Association,
South Dakota Wheat,
Inc., and the
Minnesota Barley
Growers Association.

"This public reporting session was an excellent way for growers and others in the small grains industry to learn more about the research projects supported by wheat growers in Minnesota," said David Torgerson, MWRPC executive director. Following is a run-down of 12 of the research projects:

Spring Wheat Breeding

Developing and releasing to the public improved spring wheat varieties with better agronomic traits, disease resistance, and milling and baking quality, is an ongoing research project at the U of M.

Most promising new lines from MN for yield are SBE0050, MN91227, and possibly MN91309. Scab resistance is present in the U of M breeding program, said Bob Busch, plant breeder at the U of M. MN2535 is a line with high tolerance to scab, and although it yields poorly, it has the highest test weight of all varieties and lines and the highest protein (17 percent+) by nearly 2 percent. The other scab tolerant line, MN2540, also has a high test weight with yield comparable to Marshall and Butte 86.

Both lines are being tested and increased at a faster-than-normal rate. Busch said that the extent of testing is less than normally developed varieties because of the need for scab tolerant varieties. MN2540 will undergo further testing in 1996, but MN2535 may be released as foundation seed this year, depending on evaluations by the Wheat Quality Council. Both of the accelerated lines should be viewed as varietal insurance against scab that would not be a good choice for growers in a more normal growing season, said Busch.

Screening Chinese lines for scab resistance

Charles Hu, plant pathologist, screened over 80 Chinese winter wheat lines at the U of M in search of scab tolerant traits that may be incorporated into hard red spring wheat germplasm. Busch noted

that without the grant provided by the MN Wheat Council, which supported Hu’s research before state legislative appropriations kicked in, two greenhouse seasons, or about six months of scab evaluations, would have been lost. Hu continues to screen breeding materials under evaluation this winter in Arizona.

How tillage affects scab risk

Experiments were conducted at the West Central Experiment Station in Morris, MN, to evaluate the effect of different tillage practices (moldboard plow, chisel, no-till) and crop residue (corn, wheat, soybeans) on the incidence and severity of scab. In 1995, crops on plowed ground had better yield and less scab, although surprisingly, chiseled ground in one segment of the study had more scab than no-till. This may be due in part to competition among different fungi growing in the no-till plots, reducing the incidence of scab. Results so far must be interpreted cautiously. Another year of research is needed for more conclusive recommendations that may help farmers deal with scab through tillage management practices. However, it is unlikely that the disease will be suppressed to acceptable levels by nonchemical control measures alone.

Evaluating scab control with fungicides

It appears that there is some potential for foliar fungicides to aid in minimizing the impact of scab. A three-state study coordinated by plant pathologists Roger Jones, U of M; Marcia McMullen, NDSU; and Dale Gallenberg, SDSU, evaluated foliar fungicidal control of scab using a standardized set of treatments, including rates and timing. The study involved evaluations of foliar fungicides presently available on the market, and experimental products not yet on the market. Among the study findings:

Benomyl (Benlate) clearly provides the best current option for scab control on wheat. This is true when used alone or with mancozeb. In some field trials, mancozeb and benomyl did perform slightly better than benomyl alone. Benomyl currently is not registered for use on barley.

Scab control by mancozeb alone has been variable. Mancozeb alone does not appear to be a good option.

Results differed somewhat with location. All treatments significantly reduced scab levels and increased yield of Grandin at the Fargo testing location. At Carrington, yields of Grandin increased on treated plots, but the affect on scab severity was less dramatic.

In Minnesota, several treatments significantly reduced scab and increased yield on 2375, Norm, and Stander barley. Overall, scab levels were very low in S.D. and meaningful interpretation of the 1995 data there is difficult.

Triazole fungicides (Tilt, Folicur) are very effective in controlling foliar diseases and may supplement control of scab, particularly if used at higher rates. The problem with this group of fungicides is that registration for post-heading applications is not likely.

Maxim (fludioxonil), currently unvailable as a foliar treatment, has good activity against scab. If approved, it may be a chemical alternative for barley.

Obviously, the expense of a product and its application is an economic factor that farmers must consider. However, the results from this study will increase the database on fungicidal control of scab on a regional basis, and will give extension personnel better information for proper control measure recommendations. The researchers involved with this study recommended further evaluation of promising compounds, and that some effort be directed toward studying fungicide application techniques.

Positive Effects of Wheat Bran

A study by Joanne Slavin, with the U of M Food Science & Nutrition Department, lends further support to the fact that eating foods high in dietary fiber helps lower the risk of developing certain cancers. The focal point of Slavin’s study was wheat bran, and how substances in wheat bran — dietary fiber and lignans — interact when metabolized in the human colon to form cancer-preventive qualities. Results indicate that wheat bran in a human diet helps create dietary substances which protect against hormonally-dependent cancers, such as breast, prostrate, and colon cancers. Further research will help build upon the results of Slavin’s initial wheat bran study.

Evaluating scab research techniques

A research objective is to use greenhouse screening techniques to accelerate the development of scab-resistant spring wheat cultivars. Jackie Rudd, plant scientist at SDSU in Brookings, SD, has been studying these research techniques, to compare the precision and correlation of research methods used in the greenhouse and in the field. Ultimately, his research will help increase the efficiency of screening large populations of wheat lines for resistance to scab, particularly in an accelerated screening program.

Pinpointing desirable baking qualities

Cereal scientist Khalil Khan headed a research project at NDSU to identify factors in the gluten proteins of wheat germplasm that may be responsible for differences in breadmaking quality. Pinpointing the specific protein components that is most desirable for breadmaking will help plant breeders in early generation selections of their plant development programs. Ultimately, growers would have wheat varieties that are worth more to end users.

Counting scab spores; predicting infection periods

How many scab spores attack a wheat head in disease epidemics and non-epidemics? And can neural network models predict leaf wetness duration, which might then be used as a basis to accurately forecast a scab infection period?

NDSU plant pathologist Leonard Francl found in his research (from testing sites in seven states and Manitoba) that inoculum levels in areas of severe and moderate scab epidemics ranged from undetectable levels to hundreds of Fusarium graminearum colony forming units per head per day. The number of spores per day was highly variable, but usually counts were higher as the season progressed. Level of inoculum did not appear to be a limiting factor in scab severity in locations experiencing a moderate to severe epidemic. The association of rain with some inoculation events but not others would suggest that two different types of scab spores served as inoculum for the epidemics.

An artificial neural network that predicts the duration of wheat leaf wetness was developed and tested. Predictions averaged within two hours of actual duration when compared to weather data from the North Dakota Ag Weather Network (NDAWN) system. Wetness status was correctly predicted in over 80 percent of the cases, and the model was slightly more accurate than a statistical-decision tree hybrid model recently developed at Iowa State University. The model under development at NDSU has the advantage of predicting wetness from both dew and rainfall.

Neural networks may play a role in forecasting economically important wheat diseases, such as scab. Eventually, NDAWN data could be coordinated with the model to provide near real-time predictions for particular locations, allowing producers and crop advisors a quicker response time.

Fingerprinting Fusarium

Just as identifying different strains of diseases such as influenza help health professionals develop vaccines, there is a need to identify strains of the scab fungus, Fusarium graminearum, so that accurate evaluations can be made of inoculum sources, pathogen dispersal, spread, and host infectivity.

U of M plant geneticist Maria Gallo-Meagher has been researching methods to fingerprint the DNA of Fusarium graminearum. Results obtained so far indicate that molecular markers necessary to distinguish different species and strains of the scab disease can indeed be generated.

Further development of molecular markers may result in tremendously useful diagnostic technology, that could have significant implications on crop management strategies and crop breeding for scab resistance.

Developing a foxtail management model

Research conducted in the Northern Plains has indicated that wheat yield losses caused by green and yellow foxtail competition can vary from 0 to 47 percent. It’s been estimated that if all of the potential spring wheat acres in Minnesota were treated with a foxtail control herbicide, Minnesota spring wheat producers spent between $5.8 and $15 million for foxtail control in 1994.

U of M crop scientists Bev Durgan and Jeff Gunsolus are developing a foxtail management model for wheat, called WEEDSIM. When the model is finished in a few years, it will help wheat growers and crop advisors determine when foxtail control is needed.

Recommendations from a similar model in experimental corn plots reduced herbicide cost and amount of herbicide used by about 60 percent. If the WEEDSIM model could have the same effect on wheat, Minnesota spring wheat growers could save between $3.5 and $9 million in one growing season alone. Human exposure and environmental exposure to herbicides would also be reduced.