Differences Between Farmers and Crop Protection Service Providers in the Use of Pesticides

Pesticides, i.e. plant protection products and biocidal products, are substances that suppress, eradicate or prevent the activity of harmful organisms (WHO 2020). The use of pesticides contributes significantly to ensuring the yield of crops in terms of quantity and quality (Popp et al. 2013; Feike et al. 2022). However, the use of these products is critically questioned and refused by parts of society. Possible health risks for the population, negative effects on the environment, and uncertainties in risk assessment are cited as reasons for this rejection (Szöcs et al. 2017; Wijewardene et al. 2021). In addition, professionalism in the application of pesticides and compliance with the relevant legal regulations are sometimes critically questioned by consumers (Meyer 2018). EU-wide regulations for the approval and the use of pesticides help to reduce potential risks. In the European Union, the placing of plant protection products on the market is governed by Regulation (EC) No. 1107/2009. The EU Directive 2009/128/EC provides a common framework for the sustainable use of pesticides; the implementation of this directive is based on national action plans of the member states. Depending on the legal regulations in the EU member states, the individual federal states may also have different requirements for implementing the national action plans. In Austria, for example, the authorization of plant protection products is regulated by federal law, whereas for the application and storage individual state laws apply (BML 2023).

In the EU, a certificate of competence is required for the professional use of pesticides in agriculture (Directive 2009/128/EC). This is to ensure that the user has the necessary knowledge and skills to apply chemical pesticides properly and in compliance with all application regulations. The detailed requirements for this certificate of competence are in turn defined in national and state-specific regulations. However, only competent persons may carry out plant protection measures and only pesticides with approved active ingredients (Regulation (EC) No. 1107/2009) may be used in the individual EU member countries after an extensive evaluation procedure. Furthermore, a large number of instructions as specified in course of the authorisation have to be observed when applying a pesticide, such as the application rate, the application methods, any waiting periods.

In addition, pesticide resistance management is playing an increasingly important role in the use of pesticides. It includes all measures aimed at preventing or slowing down the development of resistance in order to ensure the full effectiveness of an active substance for as long as possible. In addition, professional resistance monitoring is essential to detect changes in the sensitivity of target organisms in time. Measures of adapted resistance management include restricting the use of pesticides with only one Mode of Action group of active ingredients, as well as using mixtures and alternating active ingredients with a different, non-cross-resistant mechanism of action. Furthermore, adhering to authorised application rates, to the optimum time of use and limiting the number of applications to what is necessary contribute significantly to resistance management (Jutsum et al. 1998; Mehl and Stenzel 2008). A qualified resistance management also requires the consideration of all non-chemical measures of integrated plant protection with the aim of impeding/minimising the occurrence of the target organisms. However, this is not a standardized procedure, but each user of pesticides is faced with the task of developing a resistance management strategy suitable for his or her farm (Börner et al. 2009).

The decision for a pesticide and the application of pesticides can be made by different persons. In many cases, this task is performed by the farmer himself/herself or by an employee of the farm. An alternative is to outsource the entire crop protection measures to a professional service provider. Due to the diversity of specifications and legal obligations, precise compliance with all specifications could be a challenge for farmers. The inter-farm use, i.e. the application of pesticides by a service provider, who is usually more experienced and familiar with the application of pesticides, could be advantageous herein this case. Benefits cited include cost savings, as the application equipment does not have to be purchased, maintained and stored, and time savings for the farmer. Environmental benefits such as the reduced use of pesticides are also assumed (Vorbach et al. 2007). Potential disadvantages linked to plant protection services include limited knowledge of local conditions, extended travel distances or an unfavorable cost-benefit ratio for farmers. However, surveys categorized these potential obstacles as minor (Vorbach et al. 2007). So far, there is a lack of data comparing farmers to crop protection service providers as well as farmers of different farm sizes regarding the use of pesticides. The official statistics on pesticides refer to the sales quantities and not to the quantity actually applied in a crop. Although there are strict recording requirements for the use of pesticides, there is little data on the quantity actually applied. In this explorative study, comparative data on the quantities of pesticides applied and the pesticides used in relation to resistance management were collected and analysed. An Austrian region characterized by mixed agriculture (arable farming and cattle husbandry) was studied. The objective of the work was to identify possible differences in the selection of pesticides, especially in terms of resistance management and application rates used, between crop protection service providers and farmers. The data will provide evidence of professionalism in pesticide use with respect to compliance and resistance management and identify potential areas for improvement.

An agricultural area in Upper Austria was selected as the study area, which is characterized by the Central European transitional climate with average precipitation of 900–1000 mm per year and an average annual temperature of 6 to 10 °C (Land Oberösterreich 2022). The study area includes the districts of Grieskirchen and Schärding, whereby the Sauwald communities in Schärding were excluded due to the deviating geological conditions. The area in Schärding is characterized by a favorable climate for agriculture, fertile soil and flat to slightly sloping areas (Kimberger 1987). Mixed farms with arable farming and animal husbandry dominate this agricultural landscape. The district of Grieskirchen is characterized by a varied landscape between the foothills of the Sauwald and the Hausruckwald and the western edge of the Welser Heide (Baumgartner 1987). In the entire area, about 56.6% of the agricultural and forestry area is arable land, 25.6% is grassland. In Grieskirchen, wheat is cultivated on 19.5% of the arable land, barley on 18.4% and corn on 31.2%. In the study area of the Schärding district, wheat is cultivated on 26.3% of the arable land, barley on 16.2% and corn on 33.7% (Agrarstrukturerhebung 2010). The farms were selected based on specified criteria by an independent person who was not involved in the study (selective sampling according to Schirmer 2009) and had to meet the following criteria: cattle husbandry, cultivation of winter wheat, winter barley and maize in crop rotation and the use of pesticides in the survey years. Cattle husbandry was chosen as a criterion because of the strong emphasis on animal husbandry on these farms with pesticide application being often a subordinate activity (R. Braun pers. comm.). The selected crops are the most widespread in this region.

Data were collected from a total of 30 farms that organized the use of chemical pesticides, i.e. plant protection products, themselves. The group of 30 farmers was divided into three size groups of ten farmers each: farms with a) < 15 ha of arable land, b) 15–50 ha and c) > 50 ha of arable land. For comparison, farms managed by a total of ten pesticide service providers who were managing plant protection tasks for 30 farms were available. The number of service providers was limited, as there are only a few of them in the region. Furthermore, the application of pesticides must be orientated towards the development of the crop and the harmful organisms and can only be carried out under suitable weather conditions. Thus, their area of operation is limited due to the technical performance and the crop-specific requirements for the respective application time windows. The data on the pesticides used came from the records for professional users in accordance with the EU Regulation on pesticides (Regulation (EC) No. 1107/2009). This information must include the name of the product, the time and dose of application as well as the area and crop on which it was applied. The records can be informal or template-based, hand-written or electronically, but must be kept up to date on a daily basis and have to be stored for four years in accordance with the OÖ Bodenschutzgesetz. The data transfer of the recordings to an Excel spreadsheet was carried out directly at farm. The data of plant protection service providers were based on invoices for the applications. The data was made available by Maschinenring OÖ, as the service providers are organized via the Maschinenring and must submit these data records for this purpose. The data included all pesticide applications from the 2016–2019 cropping seasons for winter wheat, winter barley, and corn. In addition, a personal face-to-face interview was conducted with each farmer and service provider. Furthermore, mode of action groups of the active substances contained in the products were indicated in order to be able to evaluate the alternation of mode of action groups, which is essential for an adequate resistance risk management.

Pesticide data from all farms were evaluated in Excel 2021 (version 16) using a database that contained detailed information on each pesticide used, particularly the authorised application rate, active substances, and directions for use according to the Austrian register of pesticides (BAES 2021). Products with already expired authorisation in the respective crop were evaluated based on the approval data. The application rate used was set in relation to the authorised application rate and violations of the authorised application rates were recorded. In addition, the average application rates per type of pesticide as well as underdosing of the authorised application rate were determined. The limits of a reasonable application rate that may not enhance the development of resistance were defined by experts from the advisory service (Hubert Köppl, LK Upper Austria; Roman Braun, MR Upper Austria) as follows: In case of single product applications, the application rate had to be at least 75% of the authorised application rate, and in the case of product combinations at least 50% of the authorised application rate per product. In addition, based considering the mode of action groups on the active substances contained in the individual products, it was recorded to what extent a change of mode of action groups had been carried out for each crop species in the four years of survey. According to the above-mentioned experts from the advisory service, a change in the active substance group for herbicides was considered sufficient, if at least three different active substance groups were used in one crop species in the four years of study. In the case of fungicides in barley, too, three different groups of active substances were taken as standard value. In the case of wheat, fewer different active substance groups are available, therefore, the value was set to 2. Two groups of active substances were also defined for insecticides, if they are used in a crop every four years. If pesticides were not used in a crop every four years, the requirements for an adequate resistance strategy were adopted. For example, if no insecticides were used in one year, the requirements for a suitable resistance strategy were reduced from three different active ingredient groups to two.

All farmers as well as service providers used herbicides in the years studied. Fungicides were used by 70–100% of the farmers (depending on the arable land size group), as well as by all service providers. Insecticides were applied by 50–90% of the farmers and 70% of the service providers (Fig. 1).

Resistance management was evaluated based on the change of mode of action groups in course of the years of study. This was assessed individually for each crop species and pesticide for the years of application covered. Based on the criteria defined above, all farmers and all service providers have practiced appropriate resistance management when using fungicides. For insecticide use, one service provider was found to have an inadequate resistance management. The alternation of herbicidal mode of action groups was not found to be sufficient in all cases (1–3 farmers per arable land size group as well as 2 service providers) (Fig. 1).

A total of 2387 pesticide applications were evaluated (Table 1). The evaluation refers to the number of pesticides used, whereas several products were often used as tank mixtures. Over the entire study period, 1507 plant protection applications carried out by the farmers themselves and 880 applications were conducted by service providers. In 3.69% (88 out of 2387) evaluated uses of pesticides, the authorised application rates were exceeded. According to their records, 21 of the 30 farmers and 6 of the 10 service providers frequently exceeded the permissible application rates. Exceedances were found least frequently at medium-sized farms (15–50 ha arable land) and most frequently at large farms (> 50 ha arable land). The service providers as well as the group of small farms (< 15 ha arable land) were in the middle.

The average application rate was calculated as a percentage of the authorised application rate for all herbicide, fungicide and insecticide applications (Table 2). In 238 (15.79%) of the 1507 assessed pesticide applications by farmers, the application rate was below the above specified level (75% of the authorised application rate for single product applications, 50% of the authorised application rate for product combinations). In the case of service providers, the specified application rate was reduced in 112 (12.73%) of the 880 cases evaluated. On average, farmers here applied about 17% less than the maximum permitted herbicide rate for single applications and 28% for combined applications. For fungicides, these values were 11 and 24%, respectively. Insecticides were used by slightly more than two thirds of the farmers; on average, the quantity was exceeded by 1%.

Service providers used on average 10% less than the authorized herbicide dose for individual applications. For tank mixtures, they were on par with farmers. For fungicides, these levels were about 13 and 30% below the authorised rate, respectively. For insecticides, service providers used on average about 96% of the allowable amount for single applications and half of the authorized dose, if the insecticide was applied in tank mixture.

Overall, it was found that the maximum permissible amount was reduced much more frequently than it was exceeded (Table 3). Applications with underdosing are 68% due to farmers. Considering the type of pesticides, underdosing situations are typically reported for herbicide applications (72%), compared to 27% for fungicides and only 1.4% for insecticide uses.

82 out of the documented 88 exceedances were included in further evaluations. Six non-compliances, all of them herbicides, were eliminated due to recording errors (the application in the listed form would obviously have led to a total failure of the crop). In detail, half of the exceedances were found for herbicides followed by fungicides and insecticides. Farmers were more often responsible for overdosing than service providers (Table 2).

Nine farmers and four service providers have not made any application overruns, ten persons (nine farmers, 1 service provider) exceeded one application rate during the entire survey period, while two farmers and two service providers each committed more than five exceedances (Fig. 2). Five persons (three farmers and two service providers) were responsible for nearly half (46.34%) of the 82 exceedings evaluated. The three farmers each managed farms with over 50 hectares of arable land.

The application rate was exceeded to varying degrees (Table 2). In the event of one exceedance, an application rate of 250% of the authorised application rate was determined. In about 40% of 82 cases, this exceedance was in the range of up to 10%, in 28% of the cases it was over 20% (Fig. 3). While applications with only a minor exceedance of the authorised application rate are mostly due to service providers, the situations with a clear overdosing are reported for farmers.

70% of farmers and 60% of service providers adapt their crop protection strategy to the annual climatic and economic conditions.

Regarding decision support tools, not just one but several sources were used. 50% of the farmers use the Austrian warning service (https://​warndienst.​lko.​at) for their decision making and 50% are guided by recommendations from regional consultants. Damage thresholds are only used by 40% of the farmers as a basis for decision-making.

Service providers are oriented to damage thresholds by 60% and use the Austrian warning service by 80%; furthermore, in 70% of the cases they take over the decision making for the farmer (Fig. 4).

In this study we compared the practical pesticide management of farmers and service providers to explore potential advantages and disadvantages of crop protection product application by service providers and farmers, respectively. As mentioned above, for this comparison only a reduced survey group was available to collect data from farms with comparable management within a region. However, the group is comparable in its basic structure (climatic conditions, vegetation period, arable farming with cattle farming). The service providers invoice their services via the “Maschinenring”, which is one reason why the willingness to participate was very high. We cannot rule out the possibility of bias due to self-selection by farmers/service providers—however, the responses show that even obvious misbehaviour was not concealed. Weed management in winter wheat, winter barley and maize were done by all farmers and service providers by the application of herbicides, while insecticides and fungicides were used less frequently. This is in line with Herzog et al. (2006) and emphasizes the need for weed management to ensure yield. Our accompanying questionnaire (unpublished data) showed that all applications were performed with certified application equipment. Among the users, there were three farmers who did not have a valid certificate of competence. These users were in violation of applicable law, although one of the family members was in possession of a valid certificate. The application of pesticides without valid authorization in the respective crop could not be determined from the records.

In our study, most pesticides were used in accordance with the authorisation, but there is still potential for improvement. Service providers can facilitate or relieve farmers of crop protection work, but this does not rule out application errors. However, a high level of professionalism in this work is also achieved by the farmers themselves. Based on the results, the priority for action is when the maximum permitted application rate is exceeded. Minor overdosings often occur due to technical overlaps. Tolerance limits that consider technical field application aspects would be required here. Larger overlaps that are not due to technical overlaps represent an ecological, economic and socio-political problem. To avoid inadequate information on permitted application rates and to simplify information gathering, digitization will be of great benefit. The development of databases and apps that take into account not only the indisputably essential aspect of correct registration, but especially the user-friendliness, would be of great benefit and value. The essential information must be presented in an easy-to-understand, easily accessible, target group-oriented form.

Packaging sizes adapted to different requirements and farm sizes would also be advantageous. Overruns due to other intentions can only be achieved through targeted training, information campaigns and higher quality controls. The technical advice is provided by official advisory bodies. The sales staff for pesticides also have the task of providing expert advice and information. Therefore, very high priority should be given to the technical training of this group of people. In the training of users and sales personnel, sufficient attention should be paid to the aspect of active ingredient alternation for successful resistance management. This can contribute to higher professionalism in the use of pesticides in terms of compliance and resistance management, but also to the reduction of pesticides.