Q & A WITH DR . GRADY MILLER

As a follow-up to my earlier problem , can you tell me more about how I should be cleaning my sprayer ?

For the readers , let me give you the background story to this question . A field manager contacted me in late fall with a dieback problem with their ryegrass overseed on a bermudagrass field . The overseed looked healthy during germination and early in the fall . Then , late in the fall , a large streak across the field began to fade out after a bit of warm weather .

The field manager thought the warm weather resulted in the field drying out , so they increased the irrigation amount . The irrigation did not help , and within a few weeks of noticing the symptoms , the affected area had almost no living ryegrass . I made a brief inspection , and the pattern of dead turfgrass looked like whatever caused the problem came from a boom sprayer . The field manager indicated that since the ryegrass was seeded , they had only applied one spray application of a fertilizer at a low rate . Since that was not likely the cause , we next looked at his pesticide spray records .

The previous use of the sprayer was to apply a sufonylurea herbicide on bermudagrass . That information allowed us to deduce the cause of damage . Herbicide residue was still in the tank when the turf manager mixed and sprayed the fertilizer . It does not take much sufonylurea residue in the tank , boom lines , or pump to cause damage to ryegrass . The product is also slow to kill susceptible ryegrass when it is cool ; but with warm weather , it became more efficacious . Although you may not experience any problems using only a water flush between applications of multiple products over the season , some product formulations leave residues and require a more thorough cleaning than just rinsing with water . If not removed , the residues may react with subsequent products or have direct negative consequences , as was the case here .

The label for most chemicals provides directions for cleaning spray equipment . Depending on the pesticide chemistry , the manufacturer may specify dilute ammonia , chlorine bleach , commercial cleaners , or household detergents be used for cleaning . Each has a specific purpose , and they should not be mixed together . For example , if ammonia is mixed with chlorine bleach it will produce a dangerous chlorine gas that

can severely irritate eyes and lungs . Tanks , hoses , pumps , strainers and screens may accumulate residues , so all parts of the sprayer system should be cleaned . The following is a recommended clean-out procedure , but follow a chemical ’ s label if it specifies a different process :

1 . Drain the sprayer immediately after the last load . Do not allow spray solution to remain in the tank or boom overnight . Thoroughly rinse the inside surface with clean water . Spray rinse water through the spray boom for at least five minutes .

2 . Fill the sprayer tank with clean water and add the appropriate cleaning solution . Fill the boom and hoses , and allow the agitator to operate for 15 minutes .

3 . For a few hard-to-remove chemicals , allow the sprayer to sit while full of cleaning solution for several hours ( as directed ) so that the chemical residue can be removed from inside the tank . 4 . Spray the cleaning solution through the booms . 5 . Remove the nozzles , screens and filters for cleaning with a soft brush and cleaning solution . Soaking these in cleaner may be necessary to remove some pesticide residues .

6 . Rinse the sprayer to remove cleaning solution and spray rinse water through the booms .

7 . Rinse the exterior of the entire spray system , including the boom , with clean water .

[ Note : Appropriately dispose of all rinse water at the field ( target site ) or on a pad designed to capture the solution .]

When it comes to sprayer clean-out , it is better to be safe than sorry . The best source of information on how to clean the sprayer is the product label . Make sure to keep an assortment of cleaners on hand that match the label recommendations for the products used . SFM

Grady Miller , Ph . D . Professor and Extension Turf Specialist North Carolina State University

Questions ? Send them to Grady Miller at North Carolina State University , Box 7620 , Raleigh , NC 27695-7620 , or e-mail grady _ miller @ ncsu . edu

Or , send your question to Pamela Sherratt at 202 Kottman Hall , 2001 Coffey Road , Columbus , OH 43210 or sherratt . 1 @ osu . edu

50 SportsField Management | January 2022 sportsfieldmanagementonline . com