Pesticide usage in Scotland: Soft Fruit Crops 2024

Data and methodology

Sampling and data collection

Using the June 2024 Agricultural Census [8], two samples were drawn representing soft fruit cultivation in Scotland. The first sample was selected from holdings growing soft fruit crops grown in the open (non-protected crops) and the second from holdings growing soft fruit crops in glasshouses or under walk-in plastic structures (protected crops). Protected and non-protected crops are recorded separately in the SAF and Agricultural Census. Separate samples were drawn to ensure non-protected crops were not under-represented in the sample; however, pesticide information was collected for all soft fruit crops grown on all holdings.

The country was divided into 11 land-use regions (Figure 29). Each sample was stratified by these land-use regions and according to holding size. The holding size groups were based on the total area of soft fruit crops grown. The sampling fractions used within both regions and size groups were based on the areas of relevant crops grown rather than number of holdings, so that smaller holdings would not dominate the sample.

The survey covered pesticide applications to soft fruit crops where all or the majority of the growing season was in 2024. As well as recording treatments applied directly to the crop, data was also collected on land preparation treatments prior to sowing or planting the crop.

Following an introductory letter and phone call, data were collected during a phone interview or by email. Where necessary, information was also collected from agronomists and contractors. In total, information was collected from 80 holdings growing soft fruit crops (see supporting document Table 12). These holdings represent 51 per cent of the total crop area grown.

Raising factors

National pesticide use was estimated by ratio raising. This is a standard statistical technique for producing estimates from a sample. It is the same methodology used by the other UK survey teams and has been used for all historical datasets produced by the Pesticide Survey Unit, allowing comparability over time. The sample data were multiplied by raising factors (see supporting document Table 17 and 18). These factors were calculated by comparing the sampled area in each of the two samples to the areas recorded in the Agricultural Census within each region and size group. An adjustment (see supporting document Table 19 and 20) was made for each crop within each region by applying the raising factors to the sample area of each crop grown and comparing this with the census area. This adjustment modifies the estimate to take into account differences in composition of crops encountered in the sample and those present in the population. A second adjustment was necessary for some crops which were present in the population but were not encountered in the sample in some strata. Due to the distribution of soft fruit crops in Scotland the land use regions were amalgamated into three areas before raising for non-protected crops; the North (Highlands & Islands, Caithness & Orkney, Moray and Aberdeen), Angus (the main fruit growing region in Scotland) and the South (East Fife, Lothian, Central Lowlands, Tweed Valley, Southern Uplands and Solway). North and South areas were further amalgamated before raising for protected soft fruit crops.

Detailed data tables and data used to create the charts in this report are available in Excel format in the supporting document published separately.

Changes from previous years

There are changes which should be noted when comparing the 2024 data with the previous survey.

In previous reports, the biological control agents; Neoseiulus cucumeris, Stratiolaelaps scimitus and Transeius montdorensis were known as Amblyseius cucumeris, Hypoaspis miles and Amblyseius montdorensis respectively. Where comparisons are made between the 2024 and 2022 surveys, differences in species names are taken into account and comparisons are made between the previous and reclassified species names.

In the 2022 report some physical control was incorrectly reported as carbonic acid diamide/urea, this should have been reported as unspecified physical control agents. The correct amended 2022 figures are used in this report. As a result, the unspecified physical control agents for 2022 included in this report will be different to those published in the previous report.

In the 2022 report Bacillus amyloliquefaciens strain MBI600 and Bacillus pumilus strain QST 2808 were incorrectly reported as biological control agents rather than biopesticides. This has been corrected in this report; as a result the 2022 figures for biological control agents and biopesticides will be different to those published in the previous report.

The 2024 report follows a different structure to earlier survey reports. Previously full data tables were included in survey reports. This report only includes short summary data tables for each of the crops but references full data tables published in Excel format in a supporting document. This is a similar format used in other Scottish Government accredited publications. Figures have also been improved to meet accessibility criteria.

Information about grower adoption of Integrated Pest Management (IPM) was collected during the 2024 survey. IPM data is collected and published every four years to allow IPM uptake to be monitored over time. IPM data was previously included in the soft fruit published reports. Due to resource and time constraints, this data has not been included in the 2024 report. The IPM data will be published separately on the SASA website in due course.

Data quality assurance

The dataset underwent several validation processes as follows; (i) checking for any obvious errors upon data receipt (ii) checking and identifying inconsistencies with use and pesticide approval conditions once entered into the database (iii) checking of data held in the database against the raw data. Where inconsistencies are found these are checked against the records and with the grower if necessary. Additional quality assurance is provided by sending reports for review to members of the Working Party on Pesticide Usage Surveys and other agricultural experts. In addition, the Scottish Pesticide Survey Unit is accredited to ISO 9001:2015. All survey related processes are documented in Standard Operating Procedures (SOPs) and our output is audited against these SOPs by internal auditors annually and by external auditors every three years.

Main sources of bias

The use of a random stratified sample is an appropriate survey methodology. A stratified random sample, grouped by farm size and region, is used to select holdings used in this survey. Sampling within size groups is based on area rather than numbers of holdings, so that smaller size groups are not over-represented in the sample. The pesticide survey may be subject to measurement bias as it is reliant on farmers/growers recording data accurately. As this survey is not compulsory it may also be subject to non-response bias, as growers on certain farm/holding types may be more likely to respond to the survey than others. Reserve lists of holdings are held for each stratum to allow non-responding holdings to be replaced with similar holdings.

Experience indicates that stratified random sampling, including reserves, coupled with personal interview technique, delivers the highest quality data and minimises non-response bias.

Standard errors

The figures presented in this report are produced from surveying a sample of holdings rather than a census of all the holdings in Scotland. Therefore, the figures are estimates of the total pesticide use for Scotland and should not be interpreted as exact. To give an idea of the precision of estimates, relative standard errors (RSE) for total pesticide use on soft fruit crops for both area and weight have been calculated. Standard errors are produced using the raising factors. An overall variance is calculated by summing the variance estimates for individual strata (region and size group) multiplied by the square of their raising factors. These variance estimates include a finite population correction. The overall standard error is calculated from the overall variance by taking its square root. This method of standard estimation was implemented as it is both relatively straightforward and has advantages over ratio estimator methods when within-strata sample sizes are small.

Standard errors are expressed as percentage relative standard errors for both total pesticide use by area treated and for weight applied. Larger relative standard errors mean that the estimates are less precise. A relative standard error of 0% would be achieved by a census. A relative standard error of 100% indicates that the error in the survey is of the same order as the measurement. Relative standard errors may be reduced with larger sample sizes. However, larger relative standard errors can also result from greater variability in pesticide use among holdings.

The RSE for estimates of total pesticide use on soft fruit crops in 2024 was 10% for area and 15% for weight (Table 22), compared with 12% for area and 17% for weight in 2022.

Response rates

See supporting document (see supporting documentation Table 21) which summarises the number of holdings contacted during the survey.

Financial burden to farmers

In order to minimise the burden on farmers, the survey team used non-visit methods of collection such as email, post or telephone call.

To determine the total burden that the 2024 soft fruit crop survey placed on those providing the information, the surveyors recorded the time that 79 respondents spent providing the data during the surveys. This sample represents 99% of growers surveyed. The median time taken to provide the information was eleven minutes.

The following formula was used to estimate the total cost of participating:

Burden (£) = No. surveyed x median time taken (hours) x typical hourly rate* (* using median “Full Time Gross” hourly pay for Scotland of £19.26) [10]

The total financial burden to all growers resulting from participation in the 2024 soft fruit crop survey was calculated to be £283.