There has been considerable recent interest in additives for herbicides. Growers have been approached by agricultural chemical dealers who are promoting additives for soil applied and postemergence herbicides. In some instances these additives may be advantageous, but generally, objective data does not support their use. This is particularly true of using additives with soil applied herbicides.
Herbicides applied postemergence have demonstrated considerable benefit from additives, and it is a normal practice to include crop oil concentrates, nonionic surfactants, and nitrogen materials with various herbicides. Sometimes differences in performance can be attributed to the choice of additive, however, the additive is not usually the major consideration when evaluating herbicide performance.
Iowa State University has recently received several inquiries about two additives, ACA and boron. ACA is suggested as an appropriate additive with Pursuit, while boron is suggested for use with Galaxy and Blazer.
Since Iowa State University has not investigated the use of either additive, we suggest that growers carefully evaluate the nutrient value of ACA. At this time, ISU does not recommend ACA as a herbicide additive. Because data are lacking on the feasibility of foliar fertilization in soybeans treated with ACA, growers should also consider the potential for injury.
BASF is promoting soluble boron as an additive to decrease Galaxy and Blazer injury to soybeans. University of Illinois research does not indicate any consistent response from this additive. ISU does not recommend that growers incur the added expense of boron as a herbicide additive, because soybean injury resulting from Galaxy or Blazer is not usually economically significant.