Pesticide Usage in Scotland: Rodenticides on Arable Farms 2020

Supplementary data

In addition to the collection of rodenticide usage data, farmers were also asked a series of supplementary questions relating to aspects of their farm operation, their use of non-chemical rodent control, rodenticide stewardship and their compliance with best practice in rodenticide use.

In contrast to the rodenticide usage data presented in the previous sections of this report, this information is not raised to provide national estimates of use, but is presented as responses from the sample surveyed.

Non-chemical rodent control

Farmers were asked about non-chemical methods employed for rodent control. A range of measures were conducted, with some farmers employing more than one method (Figure 10).

On holdings on which rodenticides were not used (n=47), 51 per cent of the farmers reported using one or more non-chemical controls. The most commonly encountered methods were use of cats and traps (58 and 20 per cent of all methods reported respectively). Shooting and dogs were also used to control rodents. Whilst most traps used are concussive, respondents were not asked to provide information on trap type but this will be collected in future surveys.

On holdings using rodenticides (n=221), 52 per cent reported that they used additional non-chemical methods of rodent control. Again, the most common methods used were cats and traps (46 and 25 per cent of all methods reported respectively) with lower use of dogs, shooting and ferrets.

The number of farmers reporting that they employed non-chemical rodent control was greater in 2020 than in 2018 and 2016 on holdings where rodenticides were used (52, 46 and 26 per cent respectively). For holdings where no rodenticides were used the numbers reporting the use of non-chemical rodent control was lower in 2020 than in 2018 and 2016 (51, 60 and 61 per cent respectively) but higher than that reported in 2014 (44 per cent).

Compliance with rodenticide best practice

All farmers and PCPs who were responsible for rodenticide baiting on the surveyed farms were asked about their training history and their compliance with the principles of best practice of rodenticide use⁽⁶⁾ (Table 3).

These data are expressed as percentage of respondents giving a positive answer to each question. Not all of those surveyed provided this data, responses were provided by 78 farmers, representing 94 per cent of those farmers who conducted their own rodenticide baiting and 25 PCPs, representing 69 per cent of the contractors encountered during the survey. Where statistically significant differences in the response between farmers and PCPs were found these are noted.

All PCPs and 49 per cent of farmers had attended a training course on rodenticide use. The uptake of training was significantly different between farmers and PCPs (P<0.001).

All PCPs and 99 per cent of farmers stated that they recorded the quantity and location of baits. All PCPs and farmers stated that these baits were protected from non-target animals. Bait was reported to be regularly inspected by all PCPs and farmers. Sixty-four per cent of PCPs and 65 per cent of farmers removed bait after targeted baiting periods. Therefore, levels of permanent baiting are similar to those recorded in 2018, although slightly higher for farmers (65 per cent of PCPs and 75 per cent of farmers removed bait after targeted baiting periods in 2018). The CRRU UK Rodenticide Stewardship regime published updated permanent baiting guidance in July 2019⁽⁸⁾ following changes to make the rules around permanent baiting more prescriptive.

Ninety-six per cent of PCPs and 91 per cent of farmers stated that they searched for and removed rodent carcasses. Many respondents stated they rarely saw carcasses. However, those farmers who did encounter carcasses employed a range of disposal methods; primarily burying and incineration, but also landfill and disposal in dung heaps (refer to table 3 for details).

Over half (56 per cent) of PCPs and five per cent of farmers used non-toxic indicator baits to monitor rodent activity on farm. This uptake in use of indicator baits was significantly different between farmers and PCPs (p-value <0.001). This is the first time both PCPs and farmers have been asked about the use of indicator baits.

The pattern of responses to these questions, both by farmers and PCPs, are very similar to those provided in the 2018 arable crop survey. The level of training and use of non-toxic indicator baits were the only questions where there was a significant difference between farmer and PCP response.

Farm operation data

Farmers were asked a series of questions relating to aspects of farm operation which might affect rodenticide use pattern (Table 4). Responses were provided by all 268 farms sampled.

The majority of respondents (96 per cent) were a member of a quality assurance scheme, similar to the 94 per cent recorded in 2018. A range of assurance schemes were encountered; the most common were Quality Meat Scotland (QMS) and Scottish Quality Crops (SQC). Both of these schemes specify that effective rodent control measures must be in place, although the use of anticoagulant rodenticides is not mandatory. Membership of both QMS and SQC also permits purchase and use of rodenticide products authorised under stewardship conditions. More farms that practised rodenticide baiting were members of a quality assurance scheme (99 per cent) than farms that did not use rodenticides (85 per cent) and this difference was significant (p-value <0.001).

Although all the farms surveyed grew arable crops, some were also mixed farms and 55 per cent of those surveyed kept livestock on their holding, compared to 59 per cent in 2018. Only two per cent of farms had a pig unit and four per cent had a poultry unit. These intensive livestock production sectors tend to be greater users of rodenticides due to storage of large volumes of feed and concern about feed spoilage and rodent related disease.

Lastly, 62 per cent of holdings surveyed had an on-farm grain store, and a significantly greater number of farms using rodenticides had a grain store (67 per cent) than farms that did not use rodenticides (34 per cent) (p<0.001).

In 2020, as in 2018 and 2016, statistically significant differences between those farmers using and not using rodenticides were only found in relation to quality assurance membership uptake and presence of a grain store.

Rodenticide approval and stewardship

EU and UK Regulatory risk assessments have concluded that the use of first and second generation anticoagulant rodenticides outdoors present a higher level of risk to non-target animals (such as predatory birds and mammals) than would normally be considered acceptable. As a result, outdoor use of these rodenticides would not usually be approved. However, the UK Government recognises that, despite these risks, outdoor use of anticoagulant rodenticides is necessary for rodent control.

In order to be able to re-authorise these rodenticides for use outdoors, the Government must be assured that the risks will be properly managed to minimise unacceptable effects to non-target species. This has been addressed by an industry led stewardship scheme, managed by the Campaign for Responsible Rodenticide Use (CRRU)⁽⁶⁾, which was launched in 2015.

With the launch of the stewardship scheme providing environmental risk mitigation measures for rodenticide use, HSE has from 2016, re-approved rodenticide product authorisations. As part of this re-authorisation the approval conditions for some products have been amended, notably in relation to the outdoor use of active substances that were previously restricted to use inside buildings (brodifacoum, flocoumafen and difethialone). During the last five years CRRU has continued to seek ways to strengthen the regime. The CRRU Code of Best Practice has recently been revised (September 2021) to take into account these regulatory changes and permitted practical uses of professional rodenticides. For example, in the updated code rodenticide use for permanent, pulsed or burrow baiting, or in covered and protected bait stations, is now only legal if the product label permits these 'non-standard' scenarios specifically. The updated code also includes new information about two active substances returning to the UK market, cholecalciferol and hydrogen cyanide, including their roles in rodenticide resistance management. When first published in 2015, the code's legal status was guidance. Since then, the Biocidal Products Regulation governing rodenticide authorisations has determined that "biocidal products shall be used in compliance with the terms and conditions of authorisation". These are summarised on product labels, thereby placing a legal obligation on pest controllers, farmers and gamekeepers. The 2021 Code of Best Practice also contains new details for using a risk hierarchy to plan effective rodent control at minimum risk to people, non-target animals and the environment. Pre-control environmental risk assessments are also recommended.

These changes may influence rodenticide usage patterns. As discussed earlier, it is possible that decreased rodenticide usage and increased adoption of non-chemical control reported in 2016 and 2018 may have been influenced by the introduction of the stewardship scheme and increased adherence to best practice. The slight increase in rodenticide usage and similar levels of non-chemical control reported during 2020 may suggest that behaviour and patterns of usage are plateauing after 5 years of rodenticide stewardship.

Farmers were asked a series of questions to investigate knowledge and participation in the rodenticide stewardship scheme (Table 5). Not all of those surveyed provided this data; responses were provided by 78 farmers, representing 94 per cent of those farmers who conducted their own rodenticide baiting.

Eighty seven per cent of farmers were aware of the rodenticide stewardship scheme's existence in 2020. Twenty eight per cent of the farmers surveyed had attended a stewardship compliant training scheme which provided certification acceptable for point of sale purchase of professional rodenticide products. In addition, nine per cent of farmers stated they intended to complete this training in future. In 2018, 86 per cent of farmers were aware of the scheme, 25 per cent had completed stewardship compliant rodenticide use training and 21 per cent intended to complete training in the future. The difference in intention to complete stewardship training may be due to the fact that more farmers are now trained.

Farmers were also asked how they last purchased rodenticides. The majority (72 per cent) obtained rodenticides by demonstrating membership of a stewardship compliant quality assurance scheme (69 per cent in 2018), followed by production of a stewardship compliant training certificate (26 percent, 17 per cent in 2018). No farmers reported buying amateur products in 2020 (which accounted for four per cent of purchases in 2018).