An Easy Herbicide Sprayer That Works Like A Spreader

Richard L. Parish, PhD, PE

Applying liquid products to lawns is difficult. Large, open turf areas such as golf courses, parks, and athletic fields can easily be sprayed with a broadcast boom, but a boom is difficult or impossible to use on a lawn if trees, beds, or other obstacles are present. The traditional approach for professionals has been to walk the lawn using a spray gun on the end of a long hose. This system can work well if the operator is experienced and careful, but is difficult and the results are subjective.

The Problem: Most lawn fertilizers and chemicals can be more easily applied as granules rather than liquid sprays. Using granules eliminates both the need to haul a heavy tank of water and also the difficulties inherent in liquid application to lawns. Fertilizers, fungicides, insecticides, and preemerge herbicides can be effectively applied as granules; however, postemerge herbicides present a problem. For efficacy, they need to be foliar-applied. Granular formulations are available, but for efficacy they must be on very light granules and must be applied to dew-wet foliage so that they will stick to the leaves. This restriction to dew-wet foliage severely limits the window of opportunity for professional applicators. Incidentally, testing has shown that artificially wetting the turf with sprinklers is not nearly as effective as applying to dew-wet foliage.

The Solution: A very practical solution for lawn care service professionals is to apply all products except broadleaf postemerge herbicides as granules, and then spray broadleaf herbicides on an as-needed basis. For this system to be practical, however, an applicator needs a simple, easy way to do the spraying. A small non-powered walk-behind sprayer is available that meets this need. The sprayer looks and pushes much like a rotary spreader, but carries a small jug of liquid and has a peristaltic (hose) pump on one or both wheels to force the liquid through one or two broadcast nozzles. Because the hose pump system is volumetric, the application rate does not vary with speed. The units are precalibrated to deliver 1 gallon per 1,000 ft2, and testing at the LSU AgCenter has verified that this calibration is correct and consistent. They work very effectively with broadleaf herbicides. Swath widths of three feet with one nozzle or six feet with two nozzles are available. These sprayers are relatively expensive, but effectively solve a problem for lawn care professionals.