Time To Inspect Sprayers

DR. RIC BESSIN

LEXINGTON, KENTUCKY

   As winter begins to wind down, growers need to get their equipment ready for the coming growing season. When it is time to begin spraying and planting, you don’t want to spend precious time fixing and repairing equipment. It is during this break that you have time to do some routine maintenance on your sprayers. Spray equipment in poor repair can lead to under- or over-applications, which can cost money.

   Look for Leaks

   Before starting, put on a pair of gloves for protection from leftover pesticide residues. Begin by filling the sprayer with clean water, but before engaging the pump, look for leaks from around the pump, hoses, strainers, and nozzles. Pay particular attention to the hoses, as these often show signs of wear sooner than other more durable parts.  

   Besides obvious leaks from hoses, inspect hoses for cracking and signs of dry rot as these can burst when pressurized. Places where hoses might crimp with folding booms are prone to cracking as hoses age. 

   Engage the pump and look again for leaks. Check the pressure gauge and test the cutoff valves to be sure they are working.

   Scrutinize Strainers

   The purpose of strainers is to keep gunk from reaching and plugging nozzles. With just routine use there can be significant gunk buildup with the inline strainer from the tank or the individual strainers for each of the nozzles.  Sometimes these can be cleaned with a soft brush, other times they need to be replaced.

   Next, the Nozzles

   All nozzles wear over time. This leads to increasing and irregular flow rate from nozzles and poor spray patterns. Instead of uniform applications across a field, there may be streaks due to places of over- or under-applications. While some nozzles materials, such as ceramics and stainless steel, may be more resistant to wear, all nozzles will show signs of wear eventually. Sprays containing abrasive materials, such as wettable powders and flowables, cause more wear to nozzles. Before conducting a catch test, be sure each of the nozzles are of the exact same type and are not mismatched. Start your sprayer with clean water and observe the pattern from each of the nozzles; look for streaks and clogs. The pattern from each nozzle should be the same. Run a 30-second or 1-minute catch test for each nozzle; output from each nozzle should be within 5 percent of the average output from all nozzles. Nozzles that are worn or cannot be unclogged need to be replaced and the catch test repeated.

   Regularly Recalibrate

   Now that your sprayer is working properly, it needs to be recalibrated; new strainers and nozzles can change the spray output.  Calibration should be done, at a minimum, once a year. However, for those that use a sprayer more frequently or after changing to different nozzles (going from flat fan to hollow cone for example) recalibration must be done more often. Instructions for calibrating a sprayer are in the Recordkeeping Manual for Private Pesticide Applicators. ∆

   DR. RIC BESSIN: Entomology Extension Specialist, University of Kentucky

 Figure 2. Check strainers regularly and clean or replace them as needed

 Photo: Ric Bessin, UK

 Figure 1. Crimps in hoses may lead to cracking

 Photo: Ric Bessin, UK