By Eric Yu and Ryan Miller
Most spray solutions are more than 95% water, yet water quality is rarely considered when herbicide performance comes-up short. The pH of that water and the minerals dissolved in it can directly influence how well an herbicide works once it is sprayed. Certain dissolved cations, such as calcium, magnesium, and iron, can tie up herbicides, and alkaline water can reduce how readily some products move into plant leaves. The good news is that these issues are manageable with simple water testing and the use of water conditioners or pH-buffering adjuvants.
Study Location and Treatments
A 2025 field study conducted in Rochester, Minnesota, evaluated how spray water pH adjustment, and the timing of spray solution mixing, affected waterhemp control in a corn herbicide program. All treatments included a tank mix of atrazine and Acuron GT (applied at either full or half rate) with NIS and AMS. Treatments differed by the presence or absence of a pH-lowering and buffering adjuvant (AlpHa Shot) and by the timing of spray solution mixing, mixed either six days prior to application to simulate a rain delay or at the time of spraying. Waterhemp control, density, and biomass were evaluated 24 days after treatment (DAT) and again at 112 DAT just prior to harvest.
Source : umn.edu