Extension Ag Update
May/June 2003
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Survey Details Herbicide Resistant Weeds in Soybean Fields

Researcher: Christy Sprague, Ext. Spec., Dept. Crop Sci., (217) 333-9652, By: Rob Wynstra (217) 333-9446, wynstra@uiuc.edu

Over the last 20 years, herbicide resistant weeds have emerged as a major problem in many Illinois soybeans fields. To date, nine different herbicide-resistant weed biotypes have been confirmed in the state. The herbicide resistance problem, however, has continued to spread across the state and possibly encompass other weed species.

With support from the Illinois Soybean Checkoff Board, researchers in the Department of Crop Sciences at the University of Illinois recently conducted a major survey of growers to better determine the exact scope of the problem and pinpoint important areas for future research. "In our survey, 43 percent of the respondents reported that they had encountered problems from herbicide-resistant weeds," said Christy Sprague, weed scientist with U of I Extension and coordinator for the weeds project. "They identified 26 different weed species with resistance to nine different herbicide classes. The earliest of these problems dates all the way back to 1986."

The survey indicated that waterhemp, ragweed, common lambsquarter, and common cocklebur comprised nearly 80 percent of the herbicide-resistant species in the state. Reports over the last few years have confirmed resistance in those four species to ALS inhibitors, triazine herbicides or even both of those classes. "The respondents also identified some of those weeds as being resistant to other herbicides, including the PPO inhibitors, such as Flexstar, Ultra Blazer, and Cobra," Sprague said. "Since that survey, we have indeed confirmed some waterhemp with resistance to the PPO inhibitors."

U of I weed scientists Aaron Hager and Pat Tranel are now conducting additional research to pinpoint the exact mechanisms at work in this PPO resistance.

" The survey also included reports of waterhemp not being effectively controlled by glyphosate," Sprague said. "Although some of this may be due to environmental conditions, there are some populations that do not seem to fit that explanation. Although no waterhemp population in the state has been confirmed as resistant to glyphosate, there remains some concern that this could become a problem in the future." She notes that researchers in several other Midwest states are working with some waterhemp populations that have not been effectively controlled with glyphosate. They have determined that some of those populations show increased tolerance.

The Illinois survey also identified resistance problems in several other weed species that have not yet been confirmed as resistant in the state. These include horseweed, velvetleaf, morningglory, and woolly cupgrass. "Most of these were reported by only a few respondents and may not truly be resistant," Sprague said. "In the case of horseweed, however, there are confirmed cases of resistance to ALS inhibitors in Ohio and glyphosate in Delaware, Tennessee, Kentucky, Ohio, Indiana, New Jersey, and Maryland. All of which raises some concern that this could be a potential problem in Illinois."

According to Sprague, one major advantage of the survey is that it allows researchers to more easily identify what new weed species in the state may be developing herbicide resistance. "The results let us get a better handle on what may be some of the emerging weed problems," she said. "We also can get a heads-up on the potential for certain weed species to develop resistance to major herbicides, such as glyphosate. With that kind of information, we can better focus our research on the areas that will be the most productive in dealing with any problem that we may confront in the future."

On-Farm Production and Commercial Use of Biobased Greases

Biobased greases derived from soybeans and on-farm processing have been a CSREES competitive grant focus. Partially funded by CSREES, the University of Northern Iowa's Ag-based Industrial Lubricants research program has developed SoyTraktm, an environmentally-friendly soy grease. CSREES has also funded a demonstration of on-the-farm soybean processing and grease manufacturing as a viable, value-added income source.

Norfolk Southern railroad is using SoyTraktm as an alternative to petroleum-based greases for track lubrication to reduce rail side wear and wheel flange wear in curves. The University of Northern Iowa's Ag-based Industrial Lubricants research program is licensing 24 industrial lubricants, greases, and base oils from soybean oil this year.

Biological Clocks "Wake Up" Plants


ARS News Service, Agricultural Research Service, USDA, David Elstein, (301) 504-1654, delstein@ars.usda.gov

Animal behavior has previously been shown to be shaped by 24-hour circadian rhythms that govern biological processes. Now scientists have found that these "biological clocks" exist in plants as well. Research at the Agricultural Research Service's Vegetable Laboratory in Beltsville, Md., has shown that a biological clock located in the nuclei of plant cells goes off every morning to prepare plants for their various activities.

" Circadian" is a Latin word meaning "about a day." Humans also have these rhythmic "clocks." Jet lag is an example of a person's biological clock being out of sync with the actual time of day.

ARS plant physiologist Autar K. Mattoo has found a few reasons why these inbuilt clocks go off every day in plants at precise times. He has spent considerable time specifically studying the one that controls an enzyme that modifies the protein known as D1, a critical element in the photosynthesis process. Binding phosphorus to D1 at a specific threshold provides a plant with a bio-timing signal that tells it to adjust its metabolism to face the onset of the day's brightest light. The plant also puts on "sunscreen" to protect itself from ultraviolet-B (UV-B) radiation damage.

Experiments were conducted at different times of the year and in different climates, but the theory that the "alarm" goes off a few hours before noon almost always proved true. One thing that can block the accumulation of phosphorus on D1 is the concentration of triazine and urea-type herbicides, such as atrazine and diuron. Mattoo worked on this project with researchers and students from the United States and Israel. As a result of their 22 years of collaborative research, these scientists were the first to determine the whole life cycle of the D1 protein.

Ultrasound Used to Detect Quality Beef


ARS News Service, Agricultural Research Service, USDA, David Elstein, (301) 504-1654, delstein@ars.usda.gov

In the doctor's office, obstetricians use ultrasound machines to check on the health of a fetus. On the farm, researchers are using the same device to determine which cattle will produce lean, tasty steaks. Scientists from the Agricultural Research Service and Iowa State University have found that scanning live cattle with ultrasound can determine their fat and marbling qualities just as well as measurements taken on the carcass. The technology is used most often on Angus cattle, but ultrasound can be used on all breeds.

While researchers have been using ultrasound on farm animals since the 1950s, this was one of the first studies to use it to determine fat content in beef cattle and the first to show how accurate it could be as a predictor.

Ultrasound is a small, non-invasive handheld machine that emits sound waves. These sound waves are turned into images and are displayed on a small monitor so researchers can "see" inside the body. The machine is placed on the animal's back--where rib-eye steaks are located--to see just how lean and muscular the animal is, and to determine marbling, the little pieces of flavor-adding fat in steaks.

While the scanning of each animal may only take a few minutes, the technology will be used primarily by seedstock producers to find ideal cattle for breeding. The researchers at ARS' Roman L. Hruska U.S. Meat Animal Research Center in Clay Center, Neb., and at Iowa State University developed equations to see how accurate the ultrasound is in determining quality beef. They found that ultrasound was just as good at predicting the amount of fat and marbling as traditional methods of studying the carcass.