Effective pesticide application requires attention to factors that influence product performance, such as product selection, label instructions, equipment calibration and application timing. However, one factor that doesn’t get much attention is the quality of the water used to spray the product.
For the most part, if the water runs clear, we don’t give much thought to its purity. But research clearly shows the quality of water used for spraying can affect how pesticides perform.
Extension researchers have proved that spray water pH and hardness can reduce the effectiveness of herbicides, making it vitally important for crop producers to test water sources. Hard water, or water with pH values as low as 4 or as high as 9, have been shown to lower the efficacy of herbicides, including glyphosate. An ideal pH value would be 6-7.
Spray water at a high pH can cause the molecules in some pesticides to break apart, turning the herbicide into a different compound. Pesticides normally are formulated as weak acids or neutral to weakly alkaline products. As a general rule, herbicides, insecticides and fungicides perform best in slightly acidic water. When water pH falls outside of the preferred upper or lower boundaries, product performance can be reduced.
In addition, using water with suspended solids such as silt, clay and organic matter can lower the effectiveness of pesticides with high soil sorption coefficients and soil organic carbon sorption coefficients. Herbicides with high Kd or Koc values bind tightly to soil as well as sediment and organic matter in water. So, the more sediment and organic matter in the water, the less herbicide remains available to be taken up by the plant.
Water hardness can affect some pesticides like magnets attracting opposite charges. Negatively charged pesticide molecules are attracted to the positively charged iron, calcium and magnesium cations in hard water. The binding of pesticides with these minerals creates molecules that cannot enter the target pest, or enter at a slower rate, or precipitate out of solution.
Growers can buy test kits for both pH and hardness, and there are pH adjuster treatments to neutralize spray water. Hard-water issues can sometimes be corrected by adding ammonium sulfate.
Producers are warned against making complex mixtures of herbicides, insecticides, fungicides and foliar fertilizers because the characteristics of each chemical could change the way the other chemicals perform, especially with questionable water.
In other Extension news, Texoma Agricultural loan officers, bankers, CPAs and financial advisers are often a producer’s best asset. Keeping up with market outlooks, average input costs, ag policy and new opportunities in managing risk is a challenge for all ag professionals. The Ag Lenders Market Outlook and Seminar on March 2 will bring that information together through world-class presenters right here in Wichita Falls.
The one-day seminar will be held in the MPEC. Registration will begin at 8 a.m. with the program kicking off at 8:30 a.m. and concluding at 4 p.m. The $40 fee includes all materials, lunch and refreshments. Multiple registrations from one office will cost only $35 each. The deadline for registration is Feb. 24.
Also producers are reminded that the Wichita Falls Ranch and Farm Expo is scheduled for March 7-8 at the J.S. Bridwell Agricultural Center. As in the past, pesticide applicator license holders can earn continuing education units by attending the educational programs. In addition, there will be more vendors and demonstrations during the two-day event. Last year the production bull sale was introduced, and it will feature 50 top bulls from purebred breeders in Texas and Oklahoma. This year we will be rolling out the horse quiz bowl kickoff competition for 4-H youths. This expo continues to grow under the management of Darin Dale, and it looks like this will be the biggest and best expo ever.
For more information, contact the Texas AgriLife Extension Service Wichita County office at 600 Scott Ave., Suite 200, in Wichita Falls or by calling 940-716-8610.