Cooperative Extension Service
[Title Slide - University of Arkansas Division of Agriculture, University of Arkansas Weed Science Team]
[Video showing a tractor running in a field and a weed scientist in a field showing a weed] Glyphosate herbicides are the most widely used herbicides in Arkansas, and the presence of glyphosate resistant weeds has been one of the greatest challenges in weed management.
[Table showing in the following:]
Herbicide resistance in weeds isn’t new in Arkansas. One of the first herbicide resistant weeds, Goosegrass, was confirmed to be resistant to dinitroaniline or yellow herbicides in 1989. Since then numerous weeds have become resistant to various chemistries.
[Pictures showing horseweeds in fields] Glyphosate resistant horseweed appeared in 2003 in cotton and soybean fields. Early on, resistant horseweed caused some farmers to destroy cotton in the field because there was no established management strategy.
[Pictures of the weed science team, Dr. Nilda Burgos, Dr. Dick Oliver, Dr. Jason Norsworthy, Dr. Bob Scott, and Dr. Ken Smith - Leaders in Herbicide Resistant Weed Management] The University of Arkansas Weed Science team was very busy developing control programs and recommendations to combat herbicide resistant horseweed. The team has become a leader in the field, using more than one-thousand small plots and demonstrations to control the spread of this pest. [Pictures of a weed scientist in a field and horseweed in a field] While the weed science team made strong control recommendations, it was impossible to stop the spread of a pest whose wind-borne seed can travel more than 200 miles. [Drawing showing a map of the state of Arkansas with county outlines showing original three county area and then spreading to entire Arkansas delta region.] Within three years the resistant horseweed spread from a three-county area to the entire crop area of Arkansas.
To help farmers manage this pest, the weed science team developed an extensive educational program called “Glyphosate Resistant Horseweed- Wanted Dead, Not Alive.” [Picture showing education poster - Wanted 2005 Glyphosate Resistant Horseweed wanted dead not alive, reward improved crops] Portfolios, literature, CDs, and DVDs were distributed at every meeting [Pictures of the wanted poster, portfolio and CD] and the team spread the word on how to slow resistant horseweed and preserve yields. [Picture and video showing a field day, researchers discussing and touring fields with a group of producers].
[Video and pictures showing a cotton field, a weed scientist in a soybean field field] Overall, producers adopted Extension strategies on 90 percent of cropland affected by resistant horseweed. This successful - and almost unheard of - adoption rate represents a direct impact on one-third of the cotton acres in the state. County Extension agents across the state demonstrated the findings. Agents said they had more calls about resistant weeds than another pest - soybean rust.
[Pictures showing a soybean plants with soybean rust, picture of a field, bar chart showing giant ragweed control] As soon as the team confirms a weed has resistance, the team immediately establishes plots to determine tools, timing and techniques to develop controls for resistant weeds.
[Picture showing common ragweed in a field and a drawing showing a map of the state of Arkansas with county outlines] Common Ragweed was the next weed confirmed to be resistant to glyphosate and it has only been confirmed in two counties but the weed science team will monitor its spread.
The Giant Ragweed came next with confirmed resistance. [Picture showing giant ragweed in a field and a drawing showing a map of the state of Arkansas with county outlines] The Giant Ragweed has been confirmed in three locations across the state.
[Pictures of fields with Johnsongrass] Johnsongrass was once the most troublesome weed in the mid-South but a good degree of control was possible with glyphosate resistant crops. Now glyphostate-resistant Johnsongrass has been confirmed in one county and is of great concern. It is being closely monitored while control methods are being developed.
[Pictures of fields with Ryegrass] Ryegrass has also become a serious problem in the past two years in southern Arkansas. Test plots are being studied for ryegrass control in early burn-down programs before planting.
[Pictures of researchers and producers in a field and scientists attending a symposium classroom] The Arkansas Weed Science team regularly works with researchers from the mid-South, across the United States, and the world. We hosted a Horseweed Symposium, the Palmer amaranth Roundtable, and the Ryegrass Symposium to pull together the best scientists in each of these areas to compile knowledge and develop recommendations.
[Drawing showing a map of the state of Arkansas with county outlines and shaded counties included in 2009 survey with 300 total samples] The weed science team has a very aggressive program to monitor the spread and location of glyphosate resistant ryegrass and has taken 300 samples from around the state.
[Pictures of a weed scientist in a field looking at a weed, resistant pigweed samples, drawings showing maps of the state of Arkansas with county outlines and shaded counties confirmed resistant at field rate Aplmer a. Distribution for 2006, 2007, 2008, 2009, and 2010] In 2004, the weed science team issued an alert for glyphosate resistant pigweed. In spring 2006, a resistant variety was found and calls about resistant pigweed began. Control programs were studied, but unfortunately the pigweed has spread rapidly. In 2010, resistant pigweed is confirmed in every crop county in Arkansas.
[Video showing weed scientists working with other scientists] The University of Arkansas Weed Science team worked with scientists from the University of Warwick, in England, to determine the amount of time needed for glyphosate resistance to develop. The studies determined that moving the residual herbicide from the end of a weed control program to the beginning reduced the probability that the weeds will become resistant.
[Pictures showing fields with and without pigweed] Using techniques learned from its research, the team was able to transform a field that had 350,000 viable pigweed seeds per acre to an average of less than one pigweed per 10 acres in 2010. The weed science team is very proud of being able to show farmers how clean fields are possible in glyphosate resistant areas.
[Slide - Glyphosate Tolerant Crops - Conservation Tillage > 70%, Control Cultivation < 5%, Saved 1,000,000,000 tons, video of farm equipment running in fields.] Greater than 70 percent of all cotton, soybean, and corn acres are devoted to conservation tillage and less than 5 percent of cotton and soybean fields in the South receive cultivation for weed control. The glyphosate resistant crops allow farmers to control weeds without deep tillage saving one billion tons of soil from erosion annually.
[Poster showing Zero Tolerance no escapes allowed, no seed produced, Soil Weed Seedbank Reduction Program] The weed science team has developed a “Zero Tolerance” program where no weed seed production or weed seed escapes are allowed. This program has received national recognition and caught the attention of the National Resource Conservation Service with the hope of reducing tillage and soil loss. [Sign showing NRCS National Resources Conservation Service United States Department of Agriculture]
[Pictures of weed scientists in fields] The weed science team will continue research and education efforts to determine the best management techniques for resistance.
[Video showing weed research facility, weed scientists in fields giving presentations on preventing weeds] The weed science team is committed to leadership in herbicide resistance in weed management. And the team will continue to help farmers prevent and control herbicide resistant weeds and is poised to move on to the next issue in herbicide resistance.
[Title slide - U of A University of Arkansas Division of Agriculture]
University of Arkansas System
University of Arkansas System • Division of Agriculture