Adjuvants and Spray Volume for Weed Control Peanut Notes No. 88 2020
Crop oil concentrate and nonionic surfactant are recommended as possibilities for Cobra, Cadre, Storm, Basagran, and Ultra Blazer. Depending on product, either crop oil concentrate or nonionic surfactant can be applied with clethodim-containing products. Crop oil concentrate is recommended with Poast or Poast Plus. Adjuvant is not recommended with 2,4-DB products in most cases. The general rate of crop oil concentrate is 1.0% (volume basis) water solution (1 gallon per 100 gallons water.) The rate for nonionic surfactant is 0.25% (volume basis) water solution (1 quart per 100 gallons water.) Paraquat is applied with nonionic surfactant at 0.125% (volume basis) or 1 pint per 100 gallons water. In some instances labels may call for 1 pint/acre or 1 quart/acre crop oil concentrate.
There are other adjuvants that are sold by different manufacturers. Silicone-based products and methylated seed oils are on the market. I have not looked at all of these but in general crop oil concentrate and nonionic surfactant do a good job making these herbicides perform at their best. For the broadleaf/sedge herbicides listed above, nonionic surfactant ultimately gives the same control as crop oil concentrate but just not as quickly. Peanut injury from these herbicides is transient regardless of which adjuvant you use. My preference for consistent control with clethodim products is crop oil concentrate.
To optimize control with broadleaf/sedge herbicides that are contact in nature (Cobra, Basagran, Storm, Ultra Blazer) use as much water as possible. Although spraying 25 gal/acre is better than 20 gal/acre, and 20 gal/acre is better than 15 gal/acre, differences across this range of spray volumes are relatively minor. When you get below 15 gal/acre control tends to drop considerably. For herbicides with systemic activity, higher spray volumes often result in less control, but in the 15 gal/acre range control holds well.
For better coverage, slow ground speeds. It makes a difference, especially if you are already cutting back on the spray volume per acre.