How Often Should I Check My Herbicide Sprayer Output?
I am commonly asked "How often should I check my herbicide sprayer output and/or change spray tips?" I recently posed this question to a TeeJet representative and his response was very similar to the answer I usually give "It depends". There really is no set number of acres, gallons of spray solution, or hours of operation when spray tips should be replaced. The general rule for the industry is when the spray tip's flow rate exceeds the flow rate of an equivalent, new spray tip by 10%, it is time for tip replacement. Factors that impact spray tip life include the tip material, crop protectant formulations, and water source.
The most common spray tip materials are ceramic, hardened stainless steel (HSS), stainless steel, polymer, or brass. Ceramic and HSS are the two most durable tip materials. However ceramic tips are more resistant to wear than HSS. Regular stainless steel and polymer tips equally resist wear, but are less durable than ceramic or HSS tips. Brass spray tips are the most susceptible to abrasive spray solutions and wear rapidly relative to tips manufactured from other materials.
The abrasiveness of spray solutions effect spray tip wear life significantly. Different crop protectant formulations are more abrasive than others. Dry crop protectant formulations (DF, WDG, WP) cause tips to wear more rapidly than liquid formulations (EC, L). Another source of abrasive particles in the spray solution can be from the spray water source. Minerals or fine soil particles in spray water source can greatly impact tip wear life.
The bottom line is a number of factors impact tip wear life. Determining how often tips should be checked is an individual management decision. Verifying tip flow rate is relatively easy and could be checked in a few minutes and the greater the frequency of checking, likelihood of misapplication diminishes. However, in my opinion large farm operations should verify calibration output prior each major application (check prior to applying fall herbicides over all the orchards you intend to treat then again before your next herbicide application over the entire farm) to the entire farm. For a small operation, checking once or twice a year may be adequate, but check at least yearly. Regardless of the size of your operation, spray pattern should be evaluated at least daily to assure uniform coverage and placement of herbicides.