Introduction
Current estimates suggest that worldwide expenditures on pesticides were nearly $56 billion in 2012, with nearly half (i.e., 45%) related to herbicide costs and expenses (USEPA 2017). Weed control is an important component determining the economic and environmental impacts of vegetation management in the landscape; however, the efficacy and diversity of control tools have been decreasing at rapid rates due to the evolution of herbicide-resistant weeds and more stringent registration requirements (Heap Reference Heap2023; Peters and Strek Reference Peters and Strek2017; Powles and Yu Reference Powles and Yu2010). In addition, there have been no new mechanisms of action (MOAs) introduced to the market in more than 30 yr, which creates major challenges for the future of herbicide-based weed management (Dayan Reference Dayan2019).
In the United States, managed turf area is estimated to be about 163,800 km2, making this the single largest irrigated U.S. crop (Milesi et al. Reference Milesi, Running, Elvidge, Dietz, Tuttle and Nemani2005). Turf includes residential, commercial, and institutional lawns, parks, athletic fields, and golf courses (Milesi et al. Reference Milesi, Running, Elvidge, Dietz, Tuttle and Nemani2005). With this large expanse of land, evolution of herbicide resistance has become a major concern for many turfgrass managers (Brosnan et al. Reference Brosnan, Barrett and Bhowmik2020a, 2020b), as herbicides are key for effective weed control at such large scales (Hull Reference Hull1995). Weeds can cause dramatic changes in root and canopy microenvironments in turf, which can result in undesirable outcomes in turf quality (Schmidt and Blaser Reference Schmidt, Blaser, Hanson and Juska1969). Species such as annual bluegrass (Poa annua L.) and goosegrass [Eleusine indica (L.) Gaertn.] have been confirmed to have resistance to multiple MOAs (Heap Reference Heap2023), due to strong selection pressure and their high propensity to rapidly evolve resistance to herbicides (Brosnan et al. Reference Brosnan, Elmore and Bagavathiannan2020b).
There has been an increase in public concern and perception of risk regarding the use of herbicides in turfgrass systems (Norgaard Reference Norgaard2007), as people can come into direct contact with turf herbicides, especially in urban areas (Hull Reference Hull1995). For these reasons, it is expected that over time, there will be more restrictions for herbicide use in turfgrass. Therefore, there is a clear need to develop alternative tools that reduce reliance on traditional synthetic herbicides with undesirable toxicological profiles based on current public demands, yet provide effective weed control (Morgan Reference Morgan and Combellack1992).
The increasing need for effective weed control in herbicide-resistant populations and public demands to reduce herbicide use have generated interest in using approaches based on gene technologies in weed management (Kumaran et al. Reference Kumaran, Choudhard, Legros, Sheppard, Barrett, Gardiner and Raghu2020). One tool in particular, ribonucleic acid interference (RNAi), has been shown to effectively regulate biological processes in plants, such as leaf morphology and development (Palatnik et al. Reference Palatnik, Allen, Wu, Schommer, Schwab, Carrington and Weigel2003), flowering time, floral organ identity (Aukerman and Sakai Reference Aukerman and Sakai2003), response to stress, and genome integrity (Carbonell Reference Carbonell2019). For weed control, it has been shown that 21- to 200-bp double-stranded RNA (dsRNA) molecules can be applied topically to weeds to silence target genes. After foliar application, dsRNAs are absorbed, and once inside cells, they bind and act as guides to target homologous messenger RNA (mRNA) sequences for destruction by an RNA-induced silencing complex, a natural cellular mechanism. The result of mRNA degradation is the elimination of the biosynthesis of target proteins and the potential death of weeds (Sammons et al. Reference Sammons, Ivashuta, Liu, Wang, Feng, Kouranov and Andersen2011). Importantly, several operational aspects of RNA silencing can be species specific (Reinhart et al. Reference Reinhart, Weinstein, Rhoades, Bartel and Bartel2002). Furthermore, it can prevent the production of enzymes resistant to herbicides and even of non-druggable proteins, which opens a wide range of possibilities to achieve selectivity, control weeds with target-site and non–target site herbicide resistance, and generate new MOAs.
Considering the rapid evolution of herbicide-resistant weeds and the consequent necessity for new solutions, it is necessary to understand the context in which RNAi should be developed and released for commercial use. In this regard, perceptions of this new technology by stakeholders must be a guiding criterion to identify the pathways or constraints for future adoption. In turf, aesthetics is an important factor to consider when landscaping decisions are made (Hayden et al. Reference Hayden, Cadenasso, Haver and Oki2015), so it is imperative to consider the perception of risk in the decision-making process and implementation of a new technology for turf managers. However, new technologies, such as RNAi, face an additional challenge, because potential users have no or limited understanding of how the technology works and its potential benefits and unintended effects. Therefore, they must make decisions about adoption based on limited and frequently simplified introductory information that is possibly intentionally or unintentionally biased. This lack of knowledge of the new technology may result in either a reluctance to try it or, in contrast, an inclination to favor its use, depending on needs and concerns of the potential users.
For these reasons, we conducted a targeted survey to study the views of RNAi technology according to turfgrass managers in the context of herbicide resistant weed management. The hypothesis for this survey was that due to the intrinsic interaction between the public and turfgrass management activities and the increasing potential for herbicide-resistant weeds, turfgrass managers would be open to new tools for weed management but cautious about implementation of the technology. Therefore, the objectives of this study were to understand (1) current herbicide use and importance to turfgrass managers; (2) key challenges currently faced in their organizations regarding weed management; (3) considerations for adoption of new weed control tools; and (4) turfgrass managers’ needs, perceptions, and likelihood of implementation of RNAi technology for weed management in turfgrass systems.
Materials and Methods
A survey was conducted at two turfgrass field days in 2022 in Jackson Springs and Raleigh, North Carolina, USA. Survey participants were given a short (5-min) talk describing RNAi systems, the status of the technology, and potential uses for weed control. They were also provided with a handout with details for them to have in hand when answering the survey (see Supplementary Material).
Next, the survey was distributed as paper copies to participants in attendance at the turfgrass field days, which included various positions/careers related to the turfgrass industry. The survey consisted of 13 questions (Table 1), including multiple-choice, Likert-scale, and fill-in-the-blank questions. Two questions were related to demographics (occupation and years of experience), and 11 were given to understand weed control considerations and the perception of implementing new weed control technologies. Before the survey’s distribution, the questions were tested for clarity by a group of weed and turfgrass scientists and personnel with different levels of education involved in turfgrass management at the North Carolina State University campus. A total of 157 participants started the survey, while only 141 participants completed the survey. For a survey to be considered complete for this study, more than 75% (10 out of 13) of the questions had to be answered.
Table 1. Survey questions distributed to turfgrass managers at field days in 2022 in Jackson Springs and Raleigh, North Carolina, USA.
A frequency analysis was conducted to analyze the distribution of responses across surveys. For questions 3 and 4, stakeholders were split into three groups based on the level of interaction with end users (i.e., general public), and the results were analyzed using a chi-square test for differences in proportion of responses.
Results and Discussion
Survey Demographics
The vast majority of survey respondents (i.e., 80%) were individuals who represented diverse aspects of turfgrass management (Table 2). The remaining 20% of respondents were those who represented “other” areas of expertise, including individuals from parks and recreation management, Extension agents, crop consultants, government positions, landscaping directors, athletic field management, and industry and academic turf scientists. In addition, more than half of the respondents indicated that they had 0 to 10 yr of experience, with almost one-quarter having 11 to 20 yr, and the remaining quarter having more than 20 yr of experience in their field (Table 3).
Table 2. Responses to “What is your occupation?”
a Total number of responses for this question is equal to 157, as some participants considered themselves to be a part of one or more occupation group.
b “Other” category consists of individuals from parks and recreation management, Extension agents, crop consultants, government positions, landscaping directors, athletic field management, and industry and academic turf scientists.
Table 3. Responses to “How many years have you been working in your position?”
Importance of Herbicides for Weed Management in Turf Systems
The vast majority of survey respondents (i.e., 95%) indicated that they currently use herbicides for weed control, while only 4.3% reported not using herbicides in their turfgrass operations. Less than 1% said they did not know or preferred not to answer. These findings indicate that the survey included respondents not only representing a comprehensive range of turfgrass systems but also with firsthand experience in weed control with herbicides. As nearly three-quarters of the respondents had more than 5 yr of experience, it was assumed that they had a clear understanding of the challenges associated with weed control and herbicide use.
In addition, all respondents attributed some degree of importance to weed management. For instance, more than 80% of stakeholders reported that weed management in their current position is absolutely essential or very important (Figure 1). The remainder of the sample considered that weeds have an average importance or little importance in their operations. When asked to choose key challenges faced in their positions that involved weeds, stakeholders ranked time spent managing weeds and cost of weed management as the most important (Figure 2). Herbicide-resistant weeds and the need for environmentally safe weed management solutions represented the second tier of importance, while limited weed control options, discussing weed management options with customers, and other challenges were ranked lowest.
Figure 1. Responses to “In general, how important is weed management in your job or to your organization?”
Figure 2. Responses to “What are some of the key challenges that you face in your position or at your organization involving weeds?”
Current Challenges of Weed Management
The challenges associated with time and cost constraints for weed management (Figure 2) were reflected in the factors respondents identified as important when considering new weed products for turfgrass management (Figure 3). For instance, cost, efficacy, and efficiency were a priority for more than 80% of respondents. Interestingly, although around half of the respondents considered that environmental and health impacts were important considerations, only a third of the stakeholders were worried about public perception (Figure 3).
Figure 3. Responses to “In your opinion, what are some important factors when considering a new product for turfgrass management?”
The tolerance for weeds in turfgrass systems is low (Alumai et al. Reference Alumai, Salminen, Richmond, Cardina and Grewal2008; Marshall et al. Reference Marshall, Orr, Bradley and Moorman2015). Therefore, weed management is an essential part of any profession in turf. Turfgrass systems, such as golf courses and urban lawns, are high-input systems that require a considerable amount of time, money, and chemicals to maintain aesthetics and functionality at the levels demanded by the clientele of each of those systems (Alumai et al. Reference Alumai, Salminen, Richmond, Cardina and Grewal2008; Brosnan et al. Reference Brosnan, Barrett and Bhowmik2020a; Marshall et al. Reference Marshall, Orr, Bradley and Moorman2015; Robbins et al. Reference Robbins, Polderman and Birkenholtz2001). For those reasons, we investigate how the level of interaction with the public (i.e., their clientele) could be affecting responses of survey participants to key challenges and factors and their decision making when choosing new weed control tools.
Public Interactions Influencing Management Practices
To understand how the public’s perception drives decisions in each occupation, survey participants were divided into categories related to likelihood of interacting with the public. The public were defined as end users of turfgrass products, such as golfers, people who visit parks or other recreational sites, or homeowners with lawns. Professions with low likelihood of interaction with the public included sod farm managers, golf course superintendents, and herbicide applicators. Groundskeepers (e.g., parks and recreation, public athletic fields) were considered a profession with a moderate likelihood of interaction with the public, and the profession with a high likelihood of interaction with the public was composed of lawn care providers.
When asked about key challenges faced in their position (Table 1, question 3), differences were seen in the proportion of each group of survey respondent in regard to herbicide resistance, environmentally safe weed management solutions, and discussing weed management options with customers as key challenges at their organizations (Table 4). The proportion of respondents with high levels of interactions with the public, or lawn care providers, were six times more likely to be concerned about the challenges associated with discussing weed management options with customers than respondents with low and moderate interactions with the public (Table 4). Despite these clear differences regarding interactions with the public, we did not find differences among groups of respondents when considering public perception about new weed control products (Table 5). The proportion of respondents with moderate to high levels of interaction with the public had higher concern for environmentally safe weed management solutions compared with the stakeholders with low public interaction (Table 4). When asked about important factors when considering a new product for turfgrass management, differences were seen in the proportion of each group prioritizing efficacy and efficiency (Table 5). The participants with low and high interactions with the public had a higher concern for efficacy of a new product (Table 5). Participants with high and moderate levels of interactions with the public had the highest concern for the efficiency of a product, followed by those with low public interactions (Table 5).
Table 4. Chi-square analysis of proportion of responses given by respondent groups, divided into low, moderate, and high level of interactions with the public for question 3: “What are some of the key challenges that you face in your position or at your organization?”
a The results are presented as the percentage of responses within each stakeholder group (low, moderate, or high level of interaction with the public). Survey respondents were separated into the three groups based upon their level of interaction with end users. Professions with low likelihood of interaction with the public included sod farm managers, golf course superintendents, and herbicide applicators. Groundskeepers (e.g., parks and recreation, public athletic fields) were considered a profession with a moderate likelihood of interaction with the public, and the profession with a high likelihood of interaction with the public was composed of lawn care providers.
b P-values lower than 0.05 indicate a significant difference between the respondent groups.
Table 5. Chi-square analysis of proportion of responses given by respondent groups, divided into low, moderate, and high level of interactions with the public for question 4: “In your opinion, what are some important factors when considering a new product for turfgrass management?”
a The results are presented as the percentage of responses within each respondent group (low, moderate, or high level of interaction with the public). Respondents were separated into the three groups based upon their level of interaction with end users. Professions with low likelihood of interaction with the public included sod farm managers, golf course superintendents, and herbicide applicators. Groundskeepers (e.g., parks and recreation, public athletic fields) were considered a profession with a moderate likelihood of interaction with the public, and the profession with a high likelihood of interaction with the public was composed of lawn care providers.
b P-values lower than 0.05 indicate a significant difference between the respondent groups.
In this study, positions with low levels of interaction with the public had higher levels of autonomy in regard to weed management decisions in their fields. These individuals are tasked with identifying and diagnosing problems and then designing solutions to best fit the needs of their turf fields. For example, golf course superintendents use their knowledge and experience of their golf courses to implement accurate and efficient site-specific management (Winklerprins Reference Winklerprins1999). Discussing weed management options is more of a challenge for those professions that have frequent and close interactions with the public, as is the case of lawn care professionals interacting with homeowners. Those interactions are diverse and complex, because homeowners not only have their own preferences but also can be exposed to specific requirements from public policies, local housing regulations (Jenkins Reference Jenkins1994), and peer pressure from neighbors (Byrne Reference Byrne2005). Therefore, it is understandable that lawn care professionals are more frequently involved in discussions with a diverse clientele, and they are more concerned about the nuances that drive those discussions.
Professions with moderate to high levels of interaction with the public also believed that finding environmentally safe weed management solutions was a challenge faced in their profession, as compared with professions with low interaction with the public. There is an increased concern from the public regarding the use of synthetic pesticides in urban lawns that have been associated with environmental pollution (Alumai et al. Reference Alumai, Salminen, Richmond, Cardina and Grewal2008). In addition, the impact of climate change, governmental regulations, and public perceptions have been noted to change the behavior of consumers and businesses toward their use of certain lawn care chemicals (Scotts Miracle-Gro Company 2022). Due to these rising concerns, synthetic pesticide use in these turf systems has been reduced, and the use of alternative lawn management strategies has become more available (Alumai et al. Reference Alumai, Salminen, Richmond, Cardina and Grewal2008).
The efficiency of a new product for weed control was considered an important factor for turfgrass management. However, the group with low likelihood of interacting with the public were less concerned than the group with a high likelihood of interacting with the public. This could be attributed to the lower number of herbicides registered for lawn care compared with golf courses and sod farms and the need of lawn care companies to have efficient products to manage larger areas and alleviate the labor burden associated with large-scale weed management (Robbins and Sharp Reference Robbins and Sharp2003).
New Technologies in Weed Management
When considering a description of RNAi technology provided in the survey, their current knowledge of turfgrass management, and assuming U.S. Environmental Protection Agency (USEPA) approval and registration, almost two-thirds of respondents would consider implementing this technology for weed management in the next 5 yr (Table 6). About one-third of the respondents said “maybe” to this possibility, while only a single respondent opposed the use of RNAi. Respondents who answered “yes” to implementing RNAi technology in the future were also those who indicated the need for new, effective weed control tools, environmentally safe solutions, herbicide resistance, and safety (Table 7). Participants who responded “maybe” were most concerned about needing more information, the cost, considerations of people involved, and weed control and technology (Table 7).
Table 6. Percentage of stakeholder responses to question 5: “Considering the description of RNAi technology provided earlier, your current knowledge of turfgrass management, and assuming EPA approval and registration, would you consider implementing this technology for weed management in the near future (i.e., in the next five years)?”
Table 7. Responses of turfgrass managers when asked “Why or why not? Please elaborate on your response to the previous question (i.e., question 5: “Considering the description of RNAi technology provided earlier, your current knowledge of turfgrass management, and assuming EPA approval and registration, would you consider implementing this technology for weed management in the near future [i.e., in the next five years]?”)”
a Categories were used to arrange write-in responses based upon the answer given in question 5.
b Those who responded “no” to question 5 did not respond to question 6.
Two-thirds of respondents considered that there was somewhat of or to a great extent a need for RNAi technology for weed management in their field of work (Figure 4). Less than 20% respondents thought there was very little need or no need at all for RNAi technology for weed management (Figure 4). Also, there were almost three times more respondents not knowing or choosing not to answer about the need for RNAi than there were respondents who were uncertain about using this technology themselves. This indicated that a proportion of respondents were willing to try the technology despite of not being clear about the real need for RNAi tools.
Figure 4. Responses to “To what degree (if any) is there a need for RNAi technology for weed management in your field of work?”
After pondering the description of the RNAi technology, half of the respondents considered that the benefits outweigh the risks (Figure 5), while 20% stated the benefits were equal to the risks. There was also a high level of uncertainty surrounding this question, with more than 20% of participants responding: “Don’t know, prefer not to answer” (Figure 5).
Figure 5. Responses to “Considering the description of the RNAi technology provided earlier, how do the potential benefits and risks compare?”
Next, the respondents were asked to rate a level of concern they think the public might have regarding RNAi technology for weed control. Approximately 40% believed that the public would be somewhat to greatly concerned about this technology (Figure 6), and half considered that the public would be neutral or would have little concern about the use of the technology (Figure 6).
Figure 6. Responses to “In your opinion, what do you think would be the level of concern (if any) in the general public regarding RNAi technology for weed control?”
Finally, we asked whether the respondents would be willing to test or use a product with RNAi experimentally or participate in research for developing the technology within the near future (i.e., 2 yr). Almost half of respondents (46%) said they would be willing to participate in research, 39% of respondents would consider this possibility, and 10% answered “no.” Only 4.4% respondents said: “Don’t know, prefer not to answer.”
In turfgrass management, the most dominant form of weed management is the use of herbicides (Watschke et al. Reference Watschke, Dernoeden and Shetlar2013). This reliance on herbicides is explained by the fact that turfgrass managers cannot use many methods of control common in other crop systems such as tillage or crop rotations (Brosnan et al. Reference Brosnan, Barrett and Bhowmik2020a). However, there have been multiple examples where herbicides have been restricted due to the public’s potential exposure, such as in athletic fields (Brosnan et al. Reference Brosnan, Dickson, Sorochan, Thoms and Stier2014).
The necessity to keep many of the turf systems weed-free to maintain aesthetic and functional quality (Brosnan et al. Reference Brosnan, Elmore and Bagavathiannan2020b), yet reduce the amount of herbicide used, makes RNAi a potential solution for both turfgrass managers and the concerned public. The turfgrass managers in our survey responded positively to potential use of RNAi technology for weed management, and many believed that the benefits of this technology would outweigh potential risks (Figure 5). It seems that turfgrass managers’ response to the possibility of RNAi becoming a viable solution to their weed management problems was based on “techno-optimism.” This is the belief that technology can solve current and future weed control issues, such as herbicide-resistance problems (Dentzman et al. Reference Dentzman, Gunderson and Jussaume2016). This is similar to the drivers of adoption of genetically modified organisms. For example, the expectation that glyphosate-resistant crops could simplify and even increase weed control was enough to motivate farmers to try and adopt those crops (Lucht Reference Lucht2015). The perceived usefulness of the new technology has been demonstrated as the most critical factor for potential adoption by farmers (Caffaro et al. Reference Caffaro, Cremasco, Roccato and Cavallo2020; Lucht Reference Lucht2015). Although this techno-optimism can be seen as positive in terms of implementing this new technology, it is critical to properly determine its potential impacts, positive and negative, such as whether adoption is based on realistic expectations. If this new technology is implemented, it must be made clear to beneficiaries that it is not a “silver bullet” and is not intended to replace all other methods of weed control. Furthermore, stewardship of the technology is necessary to reduce the potential overuse and loss of an important new tool for weed management. Unlike farmers and managers, the public is rarely concerned with the benefits of the new tool to solve technical aspects of production. Instead, perception of potential risks is the main driver for public acceptance (Byrne Reference Byrne2006; Lucht Reference Lucht2015; Ruibal-Mendieta and Lints Reference Ruibal-Mendieta and Lints1998). Therefore, a clear characterization and explanation of risk will likely be necessary to harmonize managers’ adoption with public acceptance.
While many respondents were positive about the use of RNAi technology for weed management, there were also some that were more skeptical. Among those who responded “maybe” to the implementation of this new technology, the majority stated that they would need more information or data to decide whether or not this is a technology they would like to see in their fields (Table 7). This “decision delay” allows for respondents to wait and see instead of quickly accepting or rejecting this technology (Gardezi and Arbuckle Reference Gardezi and Arbuckle2020; McNeill et al. Reference McNeill, Dunlop, Skinner and Morrison2015; Morton et al. Reference Morton, Roesch-McNally and Wilke2017). This skepticism is welcomed, as in the past new technologies or products, such as glyphosate- and dicamba-resistant crops, have been proven to require evaluations at incremental scales to understand not only the best way to use them for production purposes but also to make sure their benefits are long-lasting (Shaner et al. Reference Shaner, Lindenmeyer and Hostile2011).
The present study demonstrated that turfgrass managers rely on herbicides as an important tool for weed management. According to the turfgrass managers surveyed, time and cost constraints are a major challenge for weed management. Therefore, when presented with new weed control tools, such as RNAi technology, many were very optimistic about the potential of this new tool and were readily willing to use this product in their fields.
The current survey illustrates how potential users might approach the possibility of using RNAi technology for weed management in turfgrass. Overall, based on responses from 141 individuals who represent a range of turfgrass management, survey participants largely considered there to be a need for innovative technologies such as RNAi to address the multiple challenges associated with the loss of herbicides or the limitations in their use in many production systems. This willingness to try RNAi technology for weed control was accompanied by a lack of concern for the potential opposition that the general public might have to the use of this tool in their communities. However, at the same time, we recognize that the survey was distributed to individuals who attended turfgrass field day events and may not be representative of a broader range of stakeholders potentially impacted by new RNAi technologies for use in turfgrass systems. Additionally, it is likely that the explanation and handout provided to participants influenced their responses. Both were intended to provide an objective description of the technology. However, we recognize that the information provided might not be enough for respondents to make a fully informed decision. Furthermore, it is likely that under real situations, stakeholders would be exposed to both overly positive and overly negative information. From this perspective, exposure to biased information is an intrinsic part of the decision process. Therefore, future research should focus on determining how this technology should be introduced to both turfgrass managers as well as the various other stakeholder groups that could be impacted, including environmental groups, residents, and managers of homeowners associations, among others. This should be done in such a way that the development of the product is not circumscribed just to ensure control efficacy and efficiency but also encompasses strategies to inform the general public and incorporate their concerns before the technology is used at a large scale.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/wsc.2023.37
Acknowledgments
This research was partially funded by USDA-CPPM grant 2018-70006-28933 and Hatch Project NC-02653 and NC-02906. SRE was partially supported by an AgBioFEWS Fellowship of the Genetic Engineering and Society Center and the National Science Foundation. The authors declare no conflict of interests.
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