In Agricultural Research Service News
January 2005 --
Copper Oxide Effective Against Nematodes in Small Ruminants
Using copper oxide wire particles to control internal parasites in small ruminants, such as sheep and goats, is safe and effective when two grams or less are used.
That's according to a study by the Agricultural Research Service (ARS), Louisiana State University (LSU), Fort Valley State University in Georgia and other participants in the Southern Consortium for Small Ruminant Parasite Control. The researchers are studying alternatives to conventional treatments for nematode infections because of growing parasite resistance to chemical de-wormers.
Joan M. Burke, an animal scientist with the ARS Dale Bumpers Small Farm Research Center in Booneville, Ark., wants to determine optimal strategies to reduce nematode infection in sheep and goats. Copper oxide wire particles are used overseas in sheep and goats to alleviate mineral deficiencies, but that problem doesn?t exist here. However, the researchers theorized that copper supplements could improve the immune system, creating a less desirable environment for parasites.
Burke and cooperators used copper wire to find the optimal doses for controlling infections of Haemonchus contortus, commonly called barber pole worm, in hair sheep. The treatments must be restricted in order to avoid copper toxicity. They found no signs of copper toxicity at any dose tested (up to 6 grams).
Burke?s colleague James E. Miller, a veterinarian at LSU, recently found success with as little as one-half gram of wire particles for at least a four-week period, resulting in a 60- to 90-percent nematode reduction. Such a small dosage may allow more frequent treatments, especially during the infestation season.
The USDA Cooperative State Research, Education, and Extension Service?s Sustainable Agriculture Research and Education (SARE) program provided partial funding for this research.
According to Burke, future studies will include doses of two grams or less. In the meantime, producers should consult a veterinarian for de-worming advice.
ARS is the U.S. Department of Agriculture?s chief scientific research agency.
LiDAR: A Bright New Trend in Environmental Studies
The atmosphere, and especially the air around agricultural operations, is being studied in a whole new light with technology adapted by Agricultural Research Service scientists and their cooperators.
Researchers at the ARS National Soil Tilth Laboratory in Ames, Iowa, in collaboration with the University of Iowa, are examining many of the environmental and agricultural applications of the technology called LiDAR. According to ARS laboratory director Jerry Hatfield, the technology may revolutionize how the air around agricultural operations is monitored because it can pinpoint the location, distribution and nature of airborne particles.
A product of 1960s laser studies, LiDAR, for Light Detection and Ranging, is a radar-like technology that uses short pulses of laser light to detect and differentiate airborne particles, gases or molecules. Its tight, unbroken beam disperses very little as it moves away from its source.
LiDAR has been used to look at clouds and pollution plumes, hunt submarines, nab speeders and prepare topographic elements for land and ocean-floor maps. Hatfield and ARS soil scientist John Prueger -- and, at times, UI professor Bill Eichinger -- have used LiDAR to monitor the accuracy of remote sensors, water uptake by trees near rivers, and dust particles from mills, cotton gins and even odorous livestock facilities.
The team first used LiDAR in 1998, when asked by the U.S. Department of the Interior to study the effect of saltcedar, an invasive and prolific shrub that extracts large amounts of soil water while leaving behind soil-damaging salts, on western U.S. riverbanks.
More recently, they?ve used it in a series of soil moisture experiments, called SMEX, in which ARS, the National Aeronautics and Space Administration, the National Oceanic and Atmospheric Administration and numerous universities are evaluating how accurately remote sensors on satellites, aircraft and land-based towers monitor ground-level moisture.
Hatfield, through an agreement with UI, is currently studying LiDAR?s performance in evaluating dispersion dynamics around swine-production facilities.
Cataloguing Natural Pesticides? Modes of Action
Precisely how genes in fungi and weeds respond to natural pesticides, and cataloguing these responses, is the focus of cutting-edge studies by Agricultural Research Service scientists in Oxford, Miss.
Plant physiologist Stephen O. Duke, molecular biologist Scott Baerson and plant molecular geneticist Zhiqiang Pan at the ARS Natural Products Utilization Research Unit are using gene microarray technology to study how natural fungicides and herbicides affect a genetic process called transcription.
Most genes are expressed as proteins. Transcription is the first of two stages most genes undergo during this process. During transcription, genetic information from DNA is transferred to messenger RNA (mRNA). The second step, in which mRNA data is transferred to the protein, is called translation.
The researchers are currently cataloguing the effects, called "modes of action" or MOAs, of natural fungicides and herbicides on genes. This information will be gathered in a gene transcription library for fungicides. A similar library for herbicides will eventually be assembled, according to Duke.
Over time, plants and fungi have developed resistance to many agricultural pesticides, creating a need for the discovery of biologically based compounds, or biocides, with new modes of action.
Organisms treated with pesticides respond by altering the transcription of their genes, and different pesticides cause different transcription patterns. The results are ?transcription fingerprints? that can be documented and catalogued.
According to Duke, libraries of these ?fingerprints? will make it possible to screen new biocides whose MOAs are unknown, to see if their fingerprints are similar to those of other known MOAs and thus warrant further testing. Also, the approach can help researchers identify previously unknown targets of novel biocides, based on which genes are affected by the compound.
DNA microarray technology helps to identify MOAs because it simultaneously provides transcription data for every gene in an organism.Any libraries developed will be publicly available once they are considered reliable. But Duke stressed that much work still needs to be done.
Conservation Tillage Has Immediate Benefits
Many farmers believe that if they switch from conventional to conservation (no-till) farming, it'll take several years before they start seeing benefits. But Agricultural Research Service scientists in Auburn, Ala., and cooperators have found that when the move to no-till farming is done correctly, yields increase right away.
The ARS and Alabama Agricultural Experiment Station scientists started their research in 2000 on a 20-acre field, with conventional tillage on half of the field and conservation tillage on the other half. In a rotation of cotton and corn crops, cotton grown with conservation tillage produced 12 to 24 percent higher yields each year of the study?s first three years, compared to the conventionally tilled cotton.
The research project was led by ARS agronomist D. Wayne Reeves, now research leader of the agency?s J. Phil Campbell, Sr. Natural Resource Conservation Center in Watkinsville, Ga.; agricultural engineer Randy L. Raper of the ARS National Soil Dynamics Laboratory in Auburn; and Auburn University soil scientist Joey N. Shaw. The team discovered that as long as there?s an adequate amount of residue from a cover crop, transitioning to conservation tillage provides immediate benefits.
Farmers should not terminate the cover crop too early. Instead, they should plant the cover crops within recommended planting windows and let them grow until they?re three to five feet tall and spring planting is three to four weeks away. This will ensure that there is sufficient residue on the soil surface to reduce soil erosion and trap rain to maintain adequate soil moisture through the planting season.
The group has found that non-inversion plows, which will not disturb the crop residue, can be used to address soil compaction problems. But the farmer should stick to conservation tillage with high production of cover crop residue as much as possible to reap the financial -- and environmental -- rewards.
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