Via Dr. Eric Prostko, Extension Weed Scientist;
“Despite 15 years of on-farm use, I continue to receive frequent questions at winter grower meetings about cleaning sprayers of Valor residues. The Valor label has very specific instructions about the correct method for sprayer clean-out. These instructions are very labor/time intensive thus I am not sure if growers are willing to follow all the required steps, especially when in a hurry? Check out the June 3, 2013 UGA Weed Science Blog for the labeled instructions. Valent also sells their own tank cleaner, creatively named Valent Tank Cleaner, to help with this problem. Since the degree of tank-cleaning success seems to vary by grower, it might just be more of an art than science?
If you have a grower that continues to struggle with Valor clean-out issues, you might want to find out what kind of hoses are on the sprayer. Although, naked to the human eye, rubber hoses, especially older ones, often have cracks and crevices that can trap Valor residues which can then be released at a later date (Figures 1 and 2). Valor-challenged growers might want to consider replacing older rubber hoses with new polyethylene hoses. Although they can be more expensive (~$3/ft), there is some evidence to suggest that this type of hose is less likely to hold on to herbicide residues.”
|Figure 1. Scanning electron micrograph of a brand new Goodyear rubber spray hose (black, Versigard, synthetic). Photo courtesy of Drs. Gary Cundiff and Dan Reynolds, Mississippi State University, 2016.|
|Figure 2. Scanning electron micrograph of Goodyear rubber spray hose (black, Versigard, synthetic) used 8 times. Photo courtesy of Drs. Gary Cundiff and Dan Reynolds, Mississippi State University, 2016.|