Many people are beginning to consider not including traditional adjuvants with herbicides when they are including Dual Magnum in the tank. My view is that for postemergence herbicides it is important to follow closely the label recommendation on adjuvant use. I am not aware of postemergence herbicide labels stating that Dual Magnum is a replacement for nonionic surfactant or crop oil concentrate. I understand the value of residual weed control with Dual Magnum and I understand that the formulation of Dual Magnum my assist herbicides applied to foliage in their effectiveness. It is serving as an adjuvant in some mixes. But if the label calls for crop oil concentrate or nonionic surfactant, my recommendation is to include the adjuvant even if Dual Magnum is applied.
With paraquat in peanuts the rate of 80/20 nonionic surfactant is 1 pint per 100 gallons spray solution. For herbicides such as Cadre, Ultra Blazer, Storm and Cobra the rate of 80/20 nonionic surfactant is 1 quart per 100 gallons. For Basagran by itself, I recommend 1 quart of crop oil concentrate per acre for yellow nutsdege control. But Basagran can be applied with 80/20 surfactant at 1 quart per 100 gallons. Cadre, Ultra Blazer, Storm, and Cobra can also be applied with crop oil concentrate. Products that contain clethodim (grass herbicide) need crop oil concentrate in most cases. Rates vary but generally 1 quart per acre or 1.0% on a volume basis. When mixing clethodim with the broadleaf/sedge herbicides listed above crop oil concentrate needs to be included. In some instances, I will recommend 1 pint per acre of crop oil concentrate with these mixes. 2,4-DB labels generally do not indicate that adjuvant is needed. However, I will often apply 2,4-DB with 80/20 surfactant. For the other broadleaf herbicides (Cadre, Cobra, Ultra Blazer, Storm), I generally do not see a difference between 80/20 surfactant and crop oil concentrate a few weeks after application (the final result) but in some cases, the crop oil will show results more quickly than 80/20 surfactant.
With all of the above possibilities, the final decision should be made based on the product label.