Pesticide Usage in Scotland: Rodenticides on Grassland and Fodder Farms 2021

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=314), 47 per cent of the farmers reported using one or more non-chemical control approaches. The most commonly encountered methods were use of cats and traps (53 and 28 per cent of all methods reported respectively). Dogs and shooting were also used to control rodents. In addition, two per cent of farmers who did not use rodenticides (n=5) reported that rodent populations were controlled by natural predators (owls and badgers were cited).

On holdings using rodenticides (n=280), 48 per cent of farmers reported that they used additional non-chemical methods of rodent control. Again, the most common methods used were cats and traps (45 and 25 per cent of all methods reported respectively) with lower use of shooting and dogs.

PCPs were also asked if they used non-chemical methods of control. Fifty seven per cent of PCPs who responded (n=30) and were responsible for rodenticide baiting on the surveyed farms stated they used non-chemical methods of control. Seventy one per cent of all methods reported were traps and use of dogs and shooting accounted for 14 per cent each. PCPs were asked to specify the type of trap used. Fifty five per cent were snap traps (also known as break-back traps), 27 per cent were spring traps with the remainder being unspecified. Farmers were not asked to provide information on trap type but this will be collected in future surveys.

For holdings where rodenticides were used, the number of farmers reporting that they employed non-chemical rodent control was lower in 2021 than in 2017 (47 and 56 per cent respectively). For holdings where no rodenticides were used the numbers reporting the use of non-chemical control was slightly higher in 2021 than in 2017 (48 and 45 per cent respectively). Non-chemical control data were not collected in the 2013 grass and fodder farm survey as this data point was added to the rodenticide survey series in 2014. The control methods reported in this survey were very similar to those reported in the previous survey in 2017 and in recent arable surveys, with cats and traps being the most commonly used approach.

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⁽⁷⁾ (Table 3).

These data are expressed as percentage of respondents giving a positive answer to each question. Not all farmers returned compliance data and some responses were only partial. There were a total 136 farmers who conducted their own rodenticide baiting during this survey. The numbers of farmers responding to each question are provided in Table 3 to give context to the percentage yes response. Likewise, not all PCPs returned compliance data. Thirty PCPs returned some compliance data, this represented 71 per cent of the contractors encountered during this survey and collectively conducted baiting on 59 per cent of those farms using a PCP. Any evidence of a statistical difference in response between farmers and PCPs is indicated by a p-value.

There was very strong evidence for a difference in training uptake between farmers (25 per cent) and PCPs (100 per cent), (p-value ≤ 0.001). In 2017 only 12 per cent of farmers had attended a training course, less than half of that recorded in 2021.

All PCPs and 94 per cent of farmers (90 per cent in 2017) stated that they recorded the quantity and location of baits, and all PCPs and 99 per cent of farmers stated that these baits were protected from non-target animals (all PCPs stated these were tamper proof bait stations). Bait was reported to be regularly inspected by all PCPs and 98 per cent of farmers.

Seventy six per cent of PCPs and 65 per cent of farmers removed bait after targeted baiting periods. Therefore, levels of permanent baiting have declined since 2017 (Sixty eight per cent of PCPs and 57 per cent of farmers removed bait after targeted baiting periods in 2017). The CRRU UK Rodenticide Stewardship regime published updated permanent baiting guidance in July 2019⁽⁹⁾ following changes to make the rules around permanent baiting more prescriptive.

All of PCPs and 82 per cent of farmers stated that they searched for and removed rodent carcasses compared with 96 per cent of PCPs and 63 per cent of farmers in 2017. There was some evidence that compliance with this element of best practice was different between farmers and PCPs (p-value ≤ 0.05). Many respondents stated that they rarely saw carcasses. However, those farmers who did encounter carcasses employed a range of disposal methods; primarily burying and incineration, but also via landfill and disposal with fallen stock. PCPs disposed of carcasses by burial, incineration, removal by a waste contractor and landfill (refer to Table 3 for details).

There was very strong evidence for a difference in the use of non-toxic indicator baits to monitor rodent activity on farm between PCPs (63 per cent) and farmers (two per cent). (p-value ≤ 0.001). This is the first time in this series that 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 similar to those provided in the 2017 grassland and fodder crop survey. The level of training and use of non-toxic indicator baits were the only questions where there was strong evidence for a difference between farmer and PCP response with some evidence for a difference in searching for rodent carcasses.

For the first time in this data series, PCPs were asked if they had ever encountered or suspected resistance to rodenticides on farm. Twenty per cent of the responding PCPs stated they had (n=29). These PCPs were also asked if they changed bait formulation or used an alternative method in response. Sixty seven per cent stated they changed bait due to suspected resistance (three quarters of which specified they switched to using brodifacoum), 17 per cent switched to using traps and 17 per cent stated they suspected it was behavioural resistance only. Farmers were not asked about suspected resistance during this survey, but this data will be collected in future surveys.

Farm operation data

Farmers were asked a series of questions relating to aspects of farm operation which might affect rodenticide use pattern (Table 4). Not all of those surveyed provided this data, responses were provided by 594 farmers, representing 99 per cent of the farms sampled overall.

The majority of respondents (75 per cent) were a member of a quality assurance scheme, lower than the 86 per cent recorded in 2017 but greater than the 68 per cent recorded in 2013. 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. There was very strong evidence to suggest that farms that practised rodenticide baiting were more likely to be members of a quality assurance scheme (93 per cent) than farms that did not use rodenticides (60 per cent) (p-value ≤ 0.001).

Ninety-one per cent of those surveyed kept livestock on their holdings, compared to 96 per cent in 2017 and 91 per cent in 2013. Unlike the previous two surveys, there was very strong evidence that farms with livestock in 2021 were more likely to use rodenticides (p-value ≤ 0.001). Only one per cent of farms had a pig unit and two per cent had a poultry unit (same as 2017). 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 introduction.

Lastly, 19 per cent of holdings surveyed had an on-farm grain store. There was very strong evidence to suggest that a greater number of farms using rodenticides had a grain store (30 per cent) than farms that did not use rodenticides (nine per cent) (p-value ≤ 0.001).

In 2013 and 2017, very strong evidence for differences between those farmers using and not using rodenticides, were only in relation to quality assurance membership uptake and presence of a grain store. This was also true in 2021 with the additional difference that there was very strong evidence in 2021 of a greater proportion of those using rodenticides also keeping livestock.

Rodenticide approval and stewardship

EU and UK Regulatory risk assessments have concluded that the use of First and Second Generation Anticoagulant Rodenticides outdoors presents 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, 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)⁽⁷⁾, which was launched in 2015. With the launch of the stewardship scheme providing environmental risk mitigation measures for rodenticide use, the Health and Safety Executive (HSE), during 2016 and 2017, re-approved rodenticide product authorisations. As part of this re-authorisation the approval conditions for some products were 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 specifically permits these 'non-standard' scenarios. 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 have been designed to influence rodenticide usage patterns. As discussed earlier, it is likely that decreased rodenticide usage and increased use of PCPs reported in 2021 and 2017 have been influenced by the introduction of the stewardship scheme and increased requirement to adhere to best practice.

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; there were a total 136 farmers who conducted their own rodenticide baiting during this survey. The number of farmers responding to each question varied (see table 5 for details).

Fifty four per cent of farmers were aware of the rodenticide stewardship scheme's existence in 2021. Seventeen per cent of all responding farmers surveyed had attended a stewardship compliant training scheme which provided certification acceptable for point of sale purchase of professional rodenticide products. In addition, 21 per cent of farmers stated they intended to complete this training in future. In 2017, 61 per cent of farmers were aware of the scheme, seven per cent had completed stewardship compliant rodenticide use training and 32 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 or motivation to complete training has reduced now rodenticides can be purchased via membership of a compliant quality assurance scheme (this had been an interim measure during the last survey). A reduction in the number of farmers intending to complete stewardship training has also been recorded in recent rodenticide use on arable farm surveys.

Farmers were also asked how they last purchased rodenticides. The majority (78 per cent) obtained rodenticides by demonstrating membership of a stewardship compliant quality assurance scheme (53 per cent in 2017), followed by production of a stewardship compliant training certificate (16 percent, seven per cent in 2017). Nine per cent of farmers reported buying amateur products (15 per cent of purchases in 2017).