Pennsylvania Turfgrass – Michael Fidanza, Ph.D., Professor of Plant and Soil Science Pennsylvania State University, Berks Campus, Reading, PA and John Kaminski, Ph.D., Professor of Turfgrass Science Pennsylvania State University, University Park, PA
The late Dr. Houston Couch (1924 — 2004), published a series of three articles in 1984 and 1985 on methods, techniques, and other factors to improve fungicide applications to turf. He was a turfgrass pathologist at Pennsylvania State University early in his career, and at Virginia Tech for the remainder of his career. In 2002, he received the prestigious GCSAA Col. John Morley Distinguished Service Award, and was recognized in 2003 with the USGA Green Section Award. Since those ‘Dr. Couch articles’, there have been many advances in spray application equipment and technology over the past several years in both the agricultural and green industry sectors, as well as research on making adjustments to spray nozzles to improve or ensure product delivery and performance. Let’s revisit water-carrier spray volume and spray tips or nozzles.
Water-Carrier Volume. In golf course turf management, a commonly accepted rule-of-thumb is to calibrate your sprayer to deliver 1 (one) gallon of water-carrier per 1000 square feet for fairways, tees. and roughs, and 2 (two) gallons water/1000 sq ft for greens. That 1 gallon amount also is common for sports turf, lawns, and sod farms. Incidentally, 1 gal/1000 sq ft equals 43.56 gal water per acre, and 2 gal/1000 sq ft equals 87.12 gal water per acre. Some turf managers use an even 50 gal water per acre (which is 1.15 gal/1000 sq ft) or 100 gal water per acre (which is 2.3 gal/1000 sq ft). Of course, more water-carrier volume translates to longer time required to operate the sprayer and repeatedly fill the spray tank to make product applications. In turf management, we don’t have the option of flying an air- plane over a site and making aerial spray applications at a low volume of 5 gal water/acre as is the case with field crops. Proper and effective spray applications take time, and of course employee safety is a top priority.
The proper water-carrier volume is important to ensure accurate delivery and distribution of the product to ensure optimum product performance and efficacy, and to legally follow product label instructions. It also means driving your sprayer as slow as 3 to 4 mph across the turf, or walking a ‘spray hawk’ across greens, so it does take time. Calibrate your sprayer or spray system for the proper ground speed and pump pressure to deliver the amount of water-carrier volume you desire and train your employees to check the calibration periodically throughout the “spray season”.
Nozzles. The nozzle or spray tip represents the last piece of equipment to come into contact with the spray solution before it reaches the turf. Don’t let the least expensive part of your sprayer be responsible for a very expensive mistake. The nozzle forms the spray solution into spray droplets and a spray pattern. After all the careful calculations of product rates and timings and formulations, and careful calibration and maintenance of your sprayer, it all comes down to water droplets. Regularly check all nozzles on the spray boom for wear or damage, and periodically measure water output from each nozzle to ensure the same amount is dispensed or at least within 5% variance among all the nozzles along the spray boom. And what about nozzle spacing? Whether you prefer a 10″ boom height or 20″ boom height (i.e., distance from the turf surface to the bottom of the nozzles on the spray boom), make sure the space between the nozzles is equal to the boom height in a “1-to-1” ratio. For example, for a 20″ boom height, the nozzles should be spaced 20″ apart.
There are many nozzle-types available, but they are all responsible for forming the spray droplets and spray pattern. For turf applications,