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Mississippi Turfgrass – J. Bryan Unruh, Professor and Associate Director

Introduction

The use of ride-on applicators in the landscape is common in the northern and transition zones of the United States. However, it has only been in recent years that these machines have made their way south. Ride-on applicator use on warm-season landscapes has been steadily rising over the past few years.

In visiting with lawn care operators, the consensus is that the increasing difficulty in finding labor is prompting the shift towards the ride-on applicators. In a leading industry survey, 56% of survey respondents listed labor as a major concern.[i] The challenge is due to the aging workforce and the difficulty in attracting younger workers. A cursory review of Lawn & Landscape Magazine reveals several articles aimed at attracting and retaining young employees. The use of ride-on applicators is seen as a key move to keep younger workers satisfied.[ii] Ride-on applicators also allow for increased productivity since one can spray and spread at the same time. Additionally, ride-on applicators require less manual labor, putting an end to dragging hoses or pushing spreaders. The advantages and disadvantages of the ride-on applicators are listed in Table 1.

Types of Ride-on Applicators

There are basically two types of ride-on applicators: Spreader only and Spreader/Sprayer. The spreader only applicators are useful for applying granular products such as fertilizer or fertilizer sparged with a pesticide. Examples include the Ferris Rover™ Ride-On Spreader, the Spyker Ride-On Spreader, and the LESCO HPS Chariot Ride-On Spreader. Retail pricing for spreader only models range from $4,600 – $6,775.

The Spreader/Sprayer applicators allow for singular or simultaneous application of both dry and liquid products. There are two types of sprayer designs: Boomless and boom-type. The boomless sprayers employ a cluster of FloodJet® type nozzles that distribute the spray solution through a single nozzle operating at a given time. The boom sprayer, as the name implies, has three or four nozzles uniformly spaced along a rigid boom. Examples include the PermaGreen, Ferris Venture™, Z-Spray, and the Turfco T3100 Spreader & Sprayer. Retail pricing for the Spreader/Sprayer systems range from $10,000 – $13,000.

Calibrating Ride-on Pesticide Sprayers and Fertilizer Spreaders

As with any fertilizer or pesticide application equipment, calibration is critical for achieving effective pest control and providing uniform greening without yellow streaking from fertilizer misapplications. When combining two distribution methods (granular and liquid), the calibration can be quite challenging. Fortunately, Purdue University Extension has a fantastic publication on Calibrating Ride-on Pesticide Sprayers and Fertilizer Spreaders available as a free download (https://ppp.purdue.edu/wp-content/uploads/2016/08/PPP-104.pdf).

Do Ride-on Applicators Work as Well as Conventional Equipment?

As noted, proper calibration is the first step in achieving success with any application equipment. The application of fertilizer using a ride-on applicator does not differ too much from a standard push spreader. Assuming the machine is operated in the intended manner, one can achieve uniform results. Conversely, the spray delivery systems on ride-on applicators can offer some unique challenges that differ from conventional landscape sprayers – namely the low volume applications and operating the equipment in small, tight areas.

Historically, most lawncare spray volumes ranged from 1.0 – 3.0 gallons per 1,000 ft² [43 – 130 gallons per acre (gpa)] delivered through industry standard spray guns such as the Lesco ChemLawn Spray Gun or the JD9® High Pressure Spray Gun. However, most ride-on applicators are configured to deliver a quart per 1,000 ft² (11 gpa) which significantly reduces the coverage and may impact the efficacy of the plant protectant or liquid nutritionals.

For a pesticide to work properly, the active ingredient must come into contact with the target organism and remain at a lethal concentration for a specific amount of time. There are many factors that influence effective pest control – regardless of whether weeds, diseases, or insects are the targets.

Questions that should be answered prior to using a particular pesticide in a low volume applicator include:

1. Is the targeted insect or disease soil-borne or does it inhabit the foliage?
2. Does the targeted weed have attributes (e.g., waxy or pubescent leaves) that make control difficult?
3. Is the most effective pesticide for the targeted pest a contact or a systemic?
4. Does the label recommend (require) the use of adjuvants (i.e., spreaders, stickers, drift reduction agents)?
5. Relative sensitivity of the turfgrass to the pesticide being applied? Is there a margin of safety should treated areas get overlapping coverage?

A tremendous amount of research goes into the development of pesticide products and the label statements are the proven means to achieve maximum pest control while minimizing adverse impact on human and non-target exposure and environmental impact. At the present time, most pesticide manufacturers do not include instructions for low volume (ride-on) applicators. In fact, many pesticides labels include minimum carrier volumes and sprayer pressure requirements. Figure 1 is one of the few examples of a turf pesticide with low volume spray equipment instructions.

What Does the Research Say?

At the present time, few research papers report on testing the efficacy of ride-on applicators in landscape management. More is known about the use of low volume applicators, but most studies are not specifically focused on turfgrass management. The findings from this limited number of studies suggest the following:

Disease Control Appears to be Very Product/Pest Specific

Researchers at North Carolina State University compared various application methods (ride-on spreader/sprayer, spray wand, and research backpack) on Brown Patch management in tall fescue and found no differences in control (Butler et al., 2019)[iii]. The authors stated that as long as a highly efficacious fungicide is used, the application method was not a factor. Conversely, Benelli and Horvath (2015) determined that the use of low spray volumes, with or without adjuvant additives, resulted in reduced penetration of the spray solution and decreased fungicidal control of Large Patch in zoysiagrass[iv].

In the deep south, confusion exists with the naming of diseases caused by Rhizoctonia solani. For many years, the term “Brown Patch” was commonly used for diseases on both cool- and warm-season turfgrasses. However, the term “Large Patch” is now the accepted name for Rhizoctonia solani diseases affecting St. Augustinegrass, zoysiagrass, bermudagrass, and centipedegrass.

Brown Patch is primarily a leaf disease whereas Large Patch rarely produces leaf spots and generally produces rotted sheaths near the soil surface[v]. Delivery of efficacious fungicides at lower carrier volumes (i.e., via ride-on applicators), can be effective on foliar diseases (i.e., Brown Patch). However, fungicides that must be applied on the sheath or stem near the soil surface (i.e., Large Patch) require greater carrier volumes to deliver the fungicide into the turf canopy.

No published research exists reporting on the use of ride-on applicators for dollar spot (foliar disease) or take-all root rot (soil borne disease) – two common turf diseases in the deep south.

Pre- and Postemergence Weed Control

Researchers at Purdue University tested the performance of eleven postemergence broadleaf herbicides applied through boom (10 or 20 GPA) and boomless (10.9 GPA) ride-on applicators and compared it to a traditional Lesco ChemLawn Spray Gun (87 GPA), and a hand-held research grade boom sprayer (87 GPA) on dandelion and white clover[vi]. They reported no differences in dandelion or white clover control with various postemergence herbicides as influenced by application equipment. Additionally, despite a low carrier volume and coarse droplet size, weeds were equally controlled by herbicides with low-volume equipment.

Similarly, a graduate student thesis research project at the University of Nebraska compared ultra-low volume sprayer applications (2 GPA) to a conventional application (60 GPA) of Trimec Classic®, Tenacity®, and Pendulum Aqua Cap® targeting dandelion, ground ivy, and crabgrass[vii]. Across four studies, sprayer type did not produce a statistical difference.

A demonstration was conducted in conjunction with a University of Tennessee Turfgrass Field Day showing that prodiamine applied at either 11 or 80 GPA was equally effective at preventing crabgrass germination (J. Bartley, personal communication, October 3, 2019).

Landscapes in the deep south often have a tremendous number of different weed species; many of which are very difficult to control. Additionally, centipedegrass and St. Augustinegrass are particularly susceptible to herbicide injury. Oftentimes, successful control comes via a combination of an effective herbicide applied at a specified rate, carrier volume, and sequential treatments along with prescribed adjuvants. Each of these possible scenarios may or may not produce the desired results when delivered through a low volume applicator.

Application of Liquid Nutritionals

The only reported research on application of liquid nutritionals through a low volume applicator is the previously mentioned thesis from the University of Nebraska. The student applied two industry leading liquid fertilizers at 5 and 60 GPA to creeping bentgrass golf course fairways. None of the treatments differed from the untreated control on relative chlorophyll content, normalized difference vegetation index (NDVI), and tissue dry weight.

Researchers at the University of Florida conducted a large-scale demonstration trial on anemic centipedegrass looking at four liquid fertilizer products (macro- and micronutrients), each applied at a low and high label rate, and with or without an adjuvant. One week after application, only one product showed subtle differences when observed using drone imagery. At ground level, no observable differences could be detected.

Insect Control through Low Volume Applicators

At the time of writing this article, no published data exists that reports on control of the Southern Chinch Bug, White grubs, webworms, or armyworms – the most troublesome insects found in landscapes in the deep south.

The use of ride-on applicators will continue to rise given the stated reasons. At the 2019 Deep South Turf Expo, lawn care operators reported having good success with ride-on applicators and some expressed concerns that are in line with the pro’s and con’s stated herein. Additionally, chemical companies are starting to look at their products applied through low volume applicators which will greatly benefit our understanding on how to most effectively use this technology in the landscape industry in the Deep South.

[i] http://giecdn.blob.core.windows.net/fileuploads/document/2018/10/05/soi%20research%20pdf.pdf

[ii] https://www.lawnandlandscape.com/article/ride-on/

[iii] Butler, E.L., G. H. Galle, and J. P. Kerns. 2019. Influence of nitrogen rate and timing, fungicide application method, and simulated rainfall after fungicide application on brown patch severity in tall fescue. Crop, Forage, and Turfgrass Management. 5:190018.

[iv] Benelli, J. J. and B. J. Horvath. 2015. Influence of spray rate volume and adjuvant additives on fungicidal control of large path. https://archive.lib.msu.edu/tic/ressum/2016/191.pdf

[v] https://hgic.clemson.edu/factsheet/brown-patch-large-patch-diseases-of-lawns/

[vi] Patton, A. J., D. V. Weisenberger, G. P. Schortgen, J. C. Fausey, and J. M. Breuninger. 2018. Performance of postemergence broadleaf herbicides applied with novel lawn care application equipment. Crop, Forage, and Turfgrass Management. 4:180039.

[vii] Ferguson, J. C. 2013. Application carrier volume: A comprehensive evaluation of an ultra-low volume sprayer compared to conventional sprayer for row-crop and turfgrass production systems. Master’s thesis. University of Nebraska. Retrieved from https://digitalcommons.unl.edu/agronhortdiss/63/