K. W. Bradley, Postdoctoral Associate; E. S. Hagood, Extension Weed Specialist; Jr., K. Love, Extension Agent; and R. Heidel, Extension Agent
Virginia Polytechnic Institute and State University
Grazon P+D and Redeem R&P are two pre-packaged herbicide mixtures that will first be available for use in Virginia pastures and hayfields during the 2002 growing season. Grazon P+D contains the herbicides Tordon (picloram) and 2, 4-D while Redeem R&P contains the herbicides Garlon (triclopyr) and Stinger (clopyralid). Both of these herbicides are manufactured and sold by Dow AgroSciences. Due to the potential for injury to tobacco, soybeans, and other dicotyledonous crops, Grazon P+D will only be marketed in specific Virginia counties. As a general guideline, Grazon P+D will only be sold North of Interstate 460 and West of Interstate 95. However, there are a few 'borderline' counties that are excluded from this general guideline. Unlike Grazon P+D, Redeem R&P will be available for use throughout the state. Grazon P+D has a 7-day grazing restriction for lactating dairy cows (only) and a 30-day hay harvesting restriction for all cattle. Redeem R&P has a 14-day grazing restriction for lactating dairy cows and a 7-day hay harvesting restriction for all cattle except lactating dairy cows. For lactating dairy cows, the hay cannot be harvested until the next growing season after the Redeem R&P application.
Both of these herbicides seem to have a unique 'fit' in Virginia pastures and hayfields. Grazon P+D provides a broad-spectrum of broadleaf weed control, but provides good control of horsenettle (Solanum carolinense L.) and stickweed [Verbesina occidentalis (L.) Walt.]. Redeem R&P also provides a broad-spectrum of broadleaf weed control, but provides good control of Canada thistle [Cirsium arvense (L.) Scop.] and musk thistle (Carduus nutans L.). In addition to these 'strengths', it appears that both of these herbicides will be sold at costs equivalent to or lower than many of the herbicides that are currently used in Virginia.
During the 2001 growing season, field trials were established throughout Virginia to evaluate broadleaf weed control in pastures and hayfields with Grazon P+D, Redeem R&P, and a variety of other currently available herbicides. In both trials, 2, 4-D was applied at 1 qt/A, Banvel at 1/2 pt/A, 2, 4-D at 1 qt/A plus Banvel at 1/2 pt/A, Ally at 3/10 oz/A, Crossbow (2, 4-D + triclopyr) at 2 qts/A, Grazon P+D at 1, 2, 3, and 4 pts/A, and Redeem R&P at 1 1/2, 2, 3, and 4 pts/A. In the first field trial, a stickweed infestation in tall fescue (Festuca arundinacea Schreb.) was utilized to evaluate the effect of applying herbicides to stickweed in the vegetative (8 inch) versus the pre-bloom stage of growth (60 inch). Visible control ratings taken at the end of the growing season revealed that greater than 85% stickweed control was achieved with Grazon P+D at 2, 3, and 4 pts/A, and with Redeem R&P at 3 and 4 pts/A when these treatments were applied to stickweed in the vegetative stage of growth. Greater than 85% stickweed control was also achieved with Grazon P+D at 2, 3, and 4 pts/A, and with Redeem R&P at 4 pts/A when applied in the pre-bloom stage of growth. All other herbicides and rates generally provided less than 85% visible control of stickweed control by the end of the growing season.
In the second field trial, visible control of wild carrot (Daucus carota L.), broadleaf plantain (Plantago major L.), buckhorn plantain (Plantago lanceolata L.), poison-ivy [Toxicodendron radicans (L.) Ktze.], and bladder campion [Silene vulgaris (Moench) Garcke] was evaluated in an orchardgrass (Dactylis glomerata L.) hay field. Greater than 90% control of broadleaf and buckhorn plantain was achieved at 14 weeks after treatment (WAT) with all of the herbicides evaluated in these trials except for Banvel at _ pt/A and Redeem R&P at 1.5 pt/A. Greater than 90% control of wild carrot was also achieved with Grazon P+D at 2, 3, and 4 pts/A and Redeem R&P at 3 and 4 pts/A. All other herbicides provided significantly lower levels of wild carrot control at 14 WAT. Grazon P+D at 4 pts/A provided the highest level (83%) of poison-ivy control at 14 WAT, which was statistically similar to that provided by Grazon P+D at 3 pts/A, Redeem R&P at 4 pts/A, Crossbow at 2 qts/A, and 2, 4-D at 1 qt/A plus Banvel at 1/2 pt/A. Ally at 3/10 oz/A and Grazon P+D at 4 pts/A provided the highest levels of bladder campion control at 66 and 59%, respectively, while all other treatments provided less than 50% control at 14WAT.
Collectively, the results from these trials indicate that Grazon P+D and Redeem R&P will provide good to excellent control of many broadleaf weeds that are commonly found in Virginia pastures and hayfields. Further evaluations of these herbicides will continue in the 2002 growing season. If you have any questions pertaining to the use of either of these herbicides in Virginia, please feel free to contact. Dr. Scott Hagood at (540) 231-6762 or by e-mail at email@example.com.
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