By Mark Loux, Ohio State University Extension herbicide specialist
There are some changes with regard to soybean herbicide premixes that growers should be aware of in the coming year. Here is an overview.
Soybean herbicide premixes
Intimidator (Loveland/CPS) is a premix of s-metolachlor, fomesafen (Reflex), and metribuzin for preplant or preemergence use in soybeans. Activity is similar to a mixture of Prefix plus metribuzin. Intimidator provides broad-spectrum weed control but will be generally less effective for residual control of giant ragweed compared with other broad-spectrum soybean herbicides (Valor XLT, Gangster, Sonic, Authority XL, etc). The addition of a few ounces of metribuzin 75DF will improve marestail control, especially where the lower rates of Intimidator are used.
Matador (Loveland/CPS) is a premix of metolachlor, imazethapyr (Pursuit), and metribuzin for preplant or preemergence use in soybeans. A use rate of two pints per acre would be typical in a planned preemergence followed by postemergence soybean herbicide program. This rate provides the equivalent of 1 pound of active ingredient per acre of metolachlor, three ounces per acre of metribuzin 75DF, and 2 ounces per acre of Pursuit 2L. Matador provides broad-spectrum weed control but will generally less effective for residual control of ragweeds and marestail compared with other broad-spectrum soybean herbicides (Valor XLT, Gangster, Sonic, Authority XL, etc). Mixing this product with additional metribuzin 75DF will improve residual marestail control, and also burndown of some weeds.
Major changes with saflufenacil products within the past year or so include the addition of higher soybean burndown rates and planting restrictions, and one new product. Sharpen can now be applied at rates up to two ounces per acre in soybean burndown programs, and higher rates can improve burndown and residual broadleaf weed control. As Sharpen rates increase above one ounce per acre, the minimum interval between application and soybean planting increases. For soils with more than 2% organic matter, the minimum delay between Sharpen application and planting: one ounce — anytime before emergence; 1.5 ounces — 14 days; two ounces 30 days. Similar changes have occurred for Verdict use rates in soybeans. The five-ounce Verdict rate can be applied anytime before crop emergence, while rates of 7.5 and 10 ounces per acre must be applied 14 and 30 days before planting, respectively. On soils with 2% or less organic matter, the minimum interval between Sharpen or Verdict application and planting is 30 or 44 days even at lower rates.
Optill PRO, which is a copack of Optill plus Outook. The use rate of the copack provides the equivalent of two ounces of Optill and 10 ounces of Outlook per acre. The addition of Outlook improves control of annual grasses, pigweeds, waterhemp, and black nightshade. Outlook PRO can be applied anytime prior to cracking, or soybean emergence.
There have been some changes in the status of the labels for mixing saflufenacil products with other PPO-inhibiting herbicides since last spring. Labels in effect currently state that saflufenacil cannot be mixed with the following herbicides: flumioxazin (Valor, Valor XLT, Envive, Enlite, Gangster, Fierce); or fomesafen (Prefix, Intimidator). In addition to the prohibition of mixing, a period of 30 days must separate the application of any of these and the application of saflufenacil. Several products containing sulfentrazone can still be mixed with saflufenacil, and these include: Sonic, Authority First, and Authority XL.