| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00170 | |
| Title | Comparison of Traditional and Alternative Methods to Control Noxious Weeds near Cropland, Rangeland and Waterways |
| Investigator(s) | Zalesky, DD; LaShell, B; Selzer, D; Cook, R; Mallow, K; |
| Department | Animal Science |
| Objectives | To establish an approximately 20-acre project area to demonstrate the use of herbicidal, cultural and biological control methods. This strip of land has a variety of ecosystems including oak brush, irrigation ditch, grassland/riparian and a former oak brush stand. It serves as a barrier between an irrigated hay fields and several rangeland pastures and has the Big Stick irrigation ditch running through the North end of it. Since many heavy infestations in LaPlata County are located along irrigation waterways, the project will directly address this problem. The proposed site will include three different invasive weed treatments: intensive goat/sheep grazing, beneficial insects and herbicide treatments . Because of its unique shape (it is approximately 50 yards wide and .8 mile long) and variety of ecosystems, these treatments will be repeated across climates and for different weeds. Objectives include: * Complete comprehensive GPS mapping of weeds and ecosystems. * Demonstrate aggressive weed control methods using various levels and timings of herbicides . * Introduce goats and/or sheep to control noxious weeds with intensive grazing. * Introduce beneficial insects for long-term sustainable weed control. * Replicate treatments across ecosystems and weed infestations to compare how each of the methods affects yellow toadflax, knapweed, Canadian and musk thistle. * Monitor changes in weed infestations using GPS * Use project area for county-wide weed management activities. |
| Approach | Four distinct ecosystems (Oak brush, Irrigation ditch, Grass/riparian, and Dead Oak Brush), four prevelant weeds (Yellow TaodFlax, Musk Thistle, Canadian Thistle, and Spotted Knapweed), and three treatments (Intensive Grazing, Herbicide and Beneficial Insects) will be studied throughout this project. The following insects will be released: Ceutorhynchus litura, the Canada Thistle Stem Weevil attacks the young Canada thistle plants as they sprout from the soil in the early spring. The developing 'litura' larvae internally mine the stem of the thistle plant as the shoot elongates during the summer. The Thistle Stem Gall Fly, Urophora cardui, attacks the primary and lateral stems of Canada thistle. Adults will lay their eggs on the thistle plant in the early summer and the developing larvae stimulate the plant to form a hard, woody, stem gall. Gall formation directs nutrients away from the normal metabolic and reproductive functions of this aggressive weed. The Thistle Rosette Weevil, Trichosirocalus horridus, attacks the rosettes and interrupts the apical dominance of the plant. The Knapweed Root Weevil, Cyphocleonus achates is a large weevil that lays approximately 100 eggs at the base of older/larger spotted and diffuse knapweed plants. The developing larvae mine the central taproot, damaging the weed's vascular tissue and cause root-gall formation. The Toadflax Flower-Feeding Beetle, Brachypterolus pulicarius, is a tiny (about 2mm long) insect with a big appetite for toadflax. Adults and larvae feed inside the flowers, destroying the floral parts that produce seed. Their feeding is so effective that very few, if any, viable seeds are produced. Intensive Grazing - Goats/sheep will be placed in 100' x 100' fenced paddocks. There will be two paddocks in the irrigation ditch, oak brush and grass/riparian ecosystems and only one in the dead oak area. If possible, they will contain primarily one weed. However, the musk thistle and knapweed have not been found in large infestations so they will probably be studied in mixed paddocks. The animals will be rotated through the paddocks frequently. Plant height, density and stage of maturation will be recorded before the animals are introduced as well as when they are removed. This will allow us to quantify what they are eating and hopefully identify the most ideal time to introduce the grazing animals. Herbicide Treatments - The effects of Redeem, Curtail, Tordon, 2-4D and a 2-4D/Tordon mix in replicated treatments within each ecosystem will be compared. For all products we will do a spring, summer and fall application. We will also apply one rate to an entire 20' x 25' plot and measure the effect of the herbicide on all plant material. Herbicide plots will be approximately 1/2 of an acre including buffer zones between treatments. Pending results of GPS data, two 250' x 70' herbicide plots will be placed in each ecosystem. Each application zone will be 20' wide, 250' long with a 5' buffer zone between them. Each individual herbicide treatment will be 25' deep and 20' wide. The treatment area will be followed by a 5'x20' buffer zone. |
| Keywords | invasive weeds, intensive grazing, herbicides, beneficial insects, ecosystems |
| Progress Reports | |
| 2002 | The encroachment of invasive plant species in Southwest Colorado is a problem for many of the farms, ranches and especially the 14-hectare ranchettes. They are experiencing serious problems controlling and eradicating noxious weeds. The region served by the San Juan Basin Research Center (SJBRC) is made up of a wide variety of ecosystems, each with different ideal weed control methods. A 6 hectare project area to demonstrate the use of herbicidal, cultural and biological control methods was established across a variety of ecosystems including oak brush, irrigation ditch, grassland/riparian and a former oak brush stand. Within each ecosystem, intensive grazing, beneficial insects and herbicide treatment plots were established with replication. Yellow toadflax, musk thistle, Canadian thistle and spotted knapweed populations will be monitored in these plots using GPS/GIS technology. All plots were established and mapped. Base maps were obtained and used to generate initial maps. Because of the severe drought during the summer of 2002, no grazing or herbicide treatments were applied. Beneficial insects would have been released early in the summer if plant material and moisture had been available. Mapping of the weed populations was also delayed because of the lack of plant material. |
| 2003 | In 2002, a 6 hectare project area to demonstrate the use of herbicidal, cultural and biological control methods was established across a variety of ecosystems including oak brush, irrigation ditch, riparian and a dead oak brush stand. Within each ecosystem, intensive grazing, beneficial insects and herbicide treatment plots were established with replication. Yellow toadflax, musk thistle, canadian thistle and spotted knapweed populations will be monitored in these plots using GPS/GIS technology. Data in 2002 was limited because of severe drought. In 2003 base plant population data was compiled and all treatments were applied. Canadian thistle was the most common plant found in the irrigated (11.2%) and dead oak (15.6%) plots. Toadflax was predominant in oak brush (11.8%) while musk thistle was highest in the riparian ecosystem (17.1%). Spotted knapweed was the least prevalent plant in all ecosystems. Baseline values indicated that 40% of the riparian ecosystems area was covered in the 4 weeds being studied. Likewise, dead oak had infestations of 32.1%, irrigated was 27.9% and oak brush was 24.4%. These levels of infestations appear to be similar to what has been found in the Four Corners region on private lands. |
| 2004 | In 2002, a 6 hectare project area to demonstrate the use of herbicidal, cultural and biological control methods was established across a variety of ecosystems including oak brush, irrigation ditch, riparian and a dead oak brush stand. Within each ecosystem, intensive grazing, beneficial insects and herbicide treatment plots were established with replication. Yellow toadflax, musk thistle, canadian thistle and spotted knapweed populations are being monitored in these plots using GPS/GIS technology. Data in 2002 was limited because of severe drought. In 2003 base plant population data was compiled and all treatments were applied. In 2004, all treatments were reapplied and 15,880 data points identifying plant species were recorded. Spotted knapweed was not found in the research area in 2004 and will be omitted from the discussion. While the overall percentage change of the primary weeds from 03 to 04 (-1 .49%) was not significant, we did see significant ecosystem, treatment and ecosystem x treatment interactions. As often occurs with long term control methods, beneficial insect treatments saw no change in all of the primary weeds. Grazing treatments had the most impact (-2.66%) on toadflax due to the timing (early fall) of the 2003 grazing. Herbicide treatments had the most effect on Canadian thistle and musk thistle (-2.85% and -4.58%, respectively). Oakbrush treatment affected toadflax the most (-1.65%) while musk thistle was most affected by treatments in the riparian area (-9.51%). First year results also showed an 8.64% increase in Brome, Western and other native grasses since 2003. We will continue to collect plant data and apply treatments until 2007. |
| 2005 | In 2002, a 6 hectare project area to demonstrate the use of herbicidal, cultural and biological control methods was established across a variety of ecosystems including oak brush , irrigation ditch, riparian and a dead oak brush stand. Within each ecosystem, intensive grazing, beneficial insects and herbicide treatment plots were established with replication. Yellow toadflax (TF), musk thistle (MT), and canadian thistle (CT) are the primary populations being monitored in these plots using GPS/GIS technology. Data in 2002 was limited because of severe drought. In 2003 base plant population data was compiled and all treatments were applied. In 2004 and 2005, all treatments were reapplied and 15,880 data points identifying plant species were recorded. Grazing treatments were applied during early Summer in 2005 to increase the amount of stress placed on the primary weeds. We continue to observe significant ecosystem, treatment and ecosystem x treatment interactions in the control of MT, CT and TF. As often occurs with long term control methods, beneficial insect treatments are the slowest to impact all of the primary weeds. It is showing minimal overall progress (-3.0% and -.7 %) on CT and MT. None of the treatments are having an impact on TF populations. In fact, the populations in the beneficial insect areas continue to rise and are similar to the control data (17.5% toadflax). Herbicide treatments continue to have the most cumulative effect on CT and MT (-5.80 and - 8.20 percent, respectively). The overall levels of these weeds in the herbicide areas are approaching eradication so we do not expect additional significant change. Cumulative results showed a 16.4% increase in Brome, Western and other native grasses since 2003. We will continue to collect plant data and apply treatments until 2007. |
| 2006 | In 2002, a 6 hectare project area to demonstrate the use of herbicidal, cultural and biological control methods was established across a variety of ecosystems including oak brush , irrigation ditch, riparian and a dead oak brush stand. Within each ecosystem, intensive grazing, beneficial insects and herbicide treatment plots were established with replication. Yellow toadflax (TF), musk thistle (MT), and canadian thistle (CT) are the primary populations being monitored in these plots using GPS/GIS technology. Data in 2002 was limited because of severe drought. In 2003 base plant population data was compiled and all treatments were applied. In 2004, 2005, and 2006 all treatments were reapplied and 15,880 data points identifying plant species were recorded per year. We will continue collect plant data in 2007 . We continue to observe ecosystem, treatment and ecosystem x treatment interactions in the control of MT, CT and TF. As often occurs with long term control methods, beneficial insect treatments are the slowest to impact all of the primary weeds. Data consistently revealed an increase in all weed populations the first year, followed by a decrease in CT and MT in Year 2. Toadflax populations did not appear to be affected by the introduction of Br. Pulicarius or Mecinus janthinus in this study. Intensive grazing somewhat affected MT(-15%) and TF (-18%) but had little affect on CT in this study. Timing of grazing most likely affected initial results as plants need to be grazed prior to seed distribution. Herbicide treatments were most effective on Canadian (-83%) and musk (-91%) thistle and had little long-term effect on toadflax. All herbicides (both high and low applications) caused a significant decrease in CT and MT populations. Low levels of herbicides had little to no affect on TF populations. Telar was the only herbicide that decreased TF populations at low application rates. The most effective herbicide treatments for TF were high rates of Telar (-71%) and Tordon (-48%). Curtail and 2-4D had no affect on TF populations in this study. The overall levels of these weeds in the herbicide areas are approaching eradication so we do not expect additional significant change. In addition to weeds, we have been tracking the populations of brome, western and Other Grasses (orchard, annual bluegrass, timothy, needle and thread, and prairie junegrass) as well as bare ground and litter. Overall, useful grasses increased by 51% while bare ground decreased by 44% in the plots. The amount of litter (leaves and other debris) has decreased by 13% since 2003. |
| Impact | |
| 2002 | Field data comparing weed control methods will allow landowners in the Four Corners region to select the best method for their ecosystem, infestation and environmental conscience. Additionally, the effectiveness of grazing on yellow toadflax populations will provide local entrepreneurs with scientific data in a controlled environment. |
| 2003 | Field data comparing weed control methods will allow landowners in the Four Corners region to select the most ideal method for their ecosystem, infestation and environmental conscience. Additionally, the effectiveness of grazing on yellow toadflax populations will provide local entrepreneurs with scientific data in a controlled environment. |
| 2004 | Field data comparing weed control methods will allow landowners in the Four Corners region to select the most ideal method for their ecosystem, infestation and environmental conscience. Additionally, the effectiveness of grazing on yellow toadflax populations will provide local entrepreneurs with scientific data in a controlled environment. |
| 2005 | Applications of both low and high rates of herbicides have significantly reduced the population of Canadian and musk thistle in all of the ecosystems being studied. While Toadflax continues to be a difficult weed to control, herbicide treatments have begun to show progress. The increases in native grass populations indicate that these more desirable species can repopulate once weed infested areas. |
| 2006 | Applications of both low and high rates of herbicides have significantly reduced the population of Canadian and musk thistle in all of the ecosystems being studied. While Toadflax continues to be a difficult weed to control, high rates of herbicide treatments have begun to show progress. The increases in native grass populations indicate that these more desirable species can repopulate once weed infested areas. |
| Publications | |
| 2004 |
LaShell, B. 2004. LaPlata County Weed School. Update of traditional and alternative methods to control noxious weeds near cropland, rangeland and waterways study. Unpub. |
| 2006 |
LaShell, Beth. 2006. Weed Symposium. Comparison of Traditional and Alternative Methods to Control Noxious Weeds Near Cropland, Rangeland and Waterways Research Summary. |