Materials and methods

The survey instrument (Supplemental Fig. 1) contained identical questions as previously used by Gelernter et al. (2016). The instrument was distributed in English via online software (Qualtrics, Provo, UT, USA). A link to the survey was sent via e-mail using the mailing lists of the National Golf Foundation and the Golf Course Superintendents Association of America (GCSAA), which resulted in the link being sent to 14,033 unique golf facilities. A golf facility was defined as a business where golf could be played on one or more golf courses. The survey and the instrument link were also promoted on social media by staff of GCSAA. The survey was available for completion for 7 consecutive weeks beginning on 1 Apr 2022. Five e-mail reminders were sent to encourage survey participation as well as survey completion by respondents who had started but not completed the survey. Respondents remained anonymous within the data file by omitting their names and assigning a unique identification number. One response was allowed per golf course. Validation that a respondent was linked to a golf facility was determined by cross-referencing the information contained in the National Golf Foundation database (i.e., golf facility name, facility type, number of holes, and location) with the answers provided by the respondent on those same criteria. Data were merged with data from the same survey conducted in 2006 and 2014 to allow for a measurement of change over time. Responses were received from 1444 facilities (Fig. 1), which represented 10.1% of the known total of US golf facilities.

Survey distribution and the seven agronomic regions of the United States.

Citation: HortTechnology 33, 2; 10.21273/HORTTECH05117-22

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Survey distribution and the seven agronomic regions of the United States.

Citation: HortTechnology 33, 2; 10.21273/HORTTECH05117-22

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Survey distribution and the seven agronomic regions of the United States.

Citation: HortTechnology 33, 2; 10.21273/HORTTECH05117-22

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To provide a valid representation of US golf courses, data were weighted. Responses were categorized into one of 35 categories depending on the facility type (public or private), number of holes (9, 18, or 27+), and public green fee (<$55 or ≥$55) (Supplemental Table 1). The weights were calculated by determining the proportion of each group within the total survey response. Reliance on pesticides was calculated by determining the difference between respondents who answered “increased” with respondents who answered “decreased.”

Data analysis was conducted using PROC SURVEYfreq in SAS (version 9.4; SAS Institute, Inc., Cary, NC, USA). To determine if survey responses changed over time, years were paired. Similarly, budget categories were paired to determine differences among budgets. Differences among all-pairwise comparisons were determined using chi-square test at the 10% significance level.

Results and discussion

Golf course superintendents reported an increase in their reliance on pesticides from 2015 to 2021 (Fig. 2). Reliance on fungicides, herbicides, and insecticides increased between 2015 and 2021 to 9%, 8%, and 5% of golf facilities, respectively. Reliance on plant-growth regulators remained consistent (∼45%) with 2015 and reliance on biocontrol products (such as polyoxin D, phosphites, and corn gluten meal) declined from 25% to 14% between 2015 and 2021. The greatest increase in pesticide reliance in the 3 years before each survey occurred with nematicides. Before 2008, the nematicide fenamiphos was considered an industry standard for the treatment of nematodes in turfgrass (Crow et al. 2005); however, the sale and distribution of fenamiphos was prohibited in the turf and ornamental market in 2008 and existing stocks of fenamiphos were prohibited from use in 2014 (Keigwin 2011). These restrictions likely resulted in reliance on nematicides decreasing by 15% in 2015. From 2015 to 2021, new a.i. (such as abamectin and fluopyram) have been documented to control nematodes and result in increased turfgrass quality (Crow 2020). Thus, it is likely the increased reliance on nematicides measured from 2015 to 2021 is a result of new nematicides in the turfgrass market.

Change in reliance of US golf facilities on pest management practices during the 3 years before 2015 and 2021. Reliance percentages were calculated by determining the difference between respondents who answered “increased” with respondents who answered “decreased”; PGRs = plant growth regulators.

Citation: HortTechnology 33, 2; 10.21273/HORTTECH05117-22

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Change in reliance of US golf facilities on pest management practices during the 3 years before 2015 and 2021. Reliance percentages were calculated by determining the difference between respondents who answered “increased” with respondents who answered “decreased”; PGRs = plant growth regulators.

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Change in reliance of US golf facilities on pest management practices during the 3 years before 2015 and 2021. Reliance percentages were calculated by determining the difference between respondents who answered “increased” with respondents who answered “decreased”; PGRs = plant growth regulators.

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The pest management practices that golf course superintendents rely on the most were plant growth regulators (PGRs) and biological control practices, although reliance on biological control practices declined by nearly 50% from 2015 to 2021. Plant growth regulators have been shown to suppress weeds (Beam and Askew 2017), suppress seed head production (Peppers et al. 2020), and occasionally reduce disease severity (Inguagiato et al. 2010). Many PGRs are naturally occurring and possess a nontoxic mode of action (i.e., gibberellins, indole-3-butyric acid, and ethylene) and, thus, are not classified as conventional pesticides but rather biological pesticides by the US Environmental Protection Agency (Reilly et al. 2002). As such, PGRs are generally considered less toxic than conventional pesticides. The nontoxic mode of action along with application scheduling via the use of predictive models (Reasor et al. 2018) may have contributed to the consistent reliance on PGRs from 2015 to 2021.

Response options in the survey instrument included 17 management practices (Supplemental Fig. 1). Of those 17, the use of seven declined, nine remained the same, and one increased from 2015 to 2021 (Table 1). Monitoring weather patterns and scouting for pests were the most common management practice and were used by 93% of golf facilities. Of the management practices that were used less frequently in 2021 than in 2015, monitoring weather patterns conducive to outbreaks, improving turfgrass health, implementing cultural practices, and spot treating damage continued to be used at >86% of golf facilities. Although the use of remote sensing increased from 17% to 21% between 2007 and 2021, the frequency of using remote sensing declined from 31% to 21% between 2015 and 2021. One limitation to remote sensing is the correlation of the remote sensing data with turfgrass performance. This is a common research area, and we postulate that the usefulness of remote sensing data to the end-user will increase in time, which, if true, may lead to increased use of remote sensing technology. Further remote sensing research may hasten implementation of remote sensing into golf facility management practices. The sole management practice that was used more frequently in 2021 than in 2015 was the use of predictive models, which was used by 60% of golf facilities in 2021 and only 52% in 2015. Recent research has confirmed that modeling turfgrass growth can result in more efficient use of resources (Kreuser et al. 2017). In addition, weather-based disease warning systems using predictive models have been developed to accurately time fungicide applications (Smith et al. 2018). Thus, using predictive models to increase resource efficiency is supported by current evidence.

Table 1.

Frequency of US golf facilities that responded that they use the listed pest management practice sometimes or frequently in 2007, 2015, and 2021.

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Use of written IPM and pesticide application plans on US golf facilities increased from 2015 to 2021, whereas the use of pesticide emergency response plans remained equivalent to 2015 (Table 2). The percentage of golf facilities that use either an IPM or pesticide application plan increased from 66% to 71% from 2015 to 2021. The use of a written pest management plan was associated with the golf facility budget (Fig. 3). Golf facilities with annual budgets exceeding $1 million more frequently had written IPM plans, pesticide emergency response plans, and either an IPM or pesticide application plan than golf facilities with annual budgets less than $1 million.

Frequency of written pest management plans on US golf facilities in 2021 as influenced by the facility’s annual budget. Bars with a common letter are not significantly different according to chi-square test at the 10% significance level; IPM = integrated pest management, PA = pesticide application.

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Frequency of written pest management plans on US golf facilities in 2021 as influenced by the facility’s annual budget. Bars with a common letter are not significantly different according to chi-square test at the 10% significance level; IPM = integrated pest management, PA = pesticide application.

Citation: HortTechnology 33, 2; 10.21273/HORTTECH05117-22

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Frequency of written pest management plans on US golf facilities in 2021 as influenced by the facility’s annual budget. Bars with a common letter are not significantly different according to chi-square test at the 10% significance level; IPM = integrated pest management, PA = pesticide application.

Citation: HortTechnology 33, 2; 10.21273/HORTTECH05117-22

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Table 2.

Frequency of written pest management plans on US golf facilities in 2007, 2015, and 2021.

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The attributes of the pesticide mixing and loading areas in 2021 remained equivalent to those from 2015 with two exceptions (Table 3). First, the presence of spill kits in the mixing and loading area increased from 54% to 60% and, second, the presence of floors that contain any spills increased from 30% to 33% between 2015 and 2021. The frequency of two attributes increased from 2007 to 2021: the presence of spill kits and the collection of rinsate. All other attributes were equivalent in 2021 to preceding years. The increased use of spill kits and rinsate collection are critical components of golf course best management practices as both reduce the risk of environmental impairment by reducing the risk of unwanted chemicals from entering the environment.

Table 3.

Frequency of mixing and loading area attributes on US golf facilities in 2007, 2015, and 2021.

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Seven of the 11 attributes of pesticide storage facilities on US golf facilities in 2021 remained equivalent to those reported in 2007 (Table 4). The frequency of the storage facility to be locked declined from 90% to 87% from 2007 to 2021 but did not change from 2015 to 2021. Passive venting declined from 58% to 52% from 2007 to 2021, but the frequency increased from 2015 to 2021. Finally, explosion-proof electrical fixtures declined from 25% to 21% from 2007 to 2021. Respondents reported 65% of golf facilities had spill kits in the storage facility, which was an increase from 2007 and 2015 to 2021. Similar to the mixing and loading area, the inclusion of spill kits is a relatively minor expense that can have a significant impact on reducing environmental risk.

Table 4.

Frequency of storage facility attributes on US golf facilities in 2007, 2015, and 2021.

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Conclusions

US golf facilities increased their reliance on fungicides, herbicides, insecticides, and nematicides from 2015 to 2021. Increased availability of new pesticide chemistries may have played a role in increasing US golf facility reliance. The use of predictive models to manage pests increased from 2015 to 2021. Recent confirmatory research has validated the use of predictive models and may have contributed to the increased use of predictive models on US golf facilities. Monitoring weather patterns and scouting were the most common pest management practice on US golf facilities in 2021. The use of IPM and pesticide application plans increased from 2015 to 2021, and facilities with annual budgets that exceed $1 million used these plans more frequently than lower-budget facilities. Mixing and loading area attributes remained mostly unchanged from 2015 to 2021.

Units

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