Pesticide Usage in Scotland: Outdoor Vegetable Crops 2023

Glossary and background notes

Pesticide is used throughout this report to include commercial formulations containing active substances (a.s.) used as herbicides, fungicides, insecticides, molluscicides, nematicides, biological control agents, biopesticides, growth regulators, seed treatments and physical control. A pesticide product consists of one or more active substances co-formulated with other materials.

An active substance (or active ingredient) is any substance or micro-organism which has a general or specific action against harmful organisms; or on plants, parts of plants or plant products.

The term formulation(s) is used to describe the pesticide active substance or mixture of active substances in a product(s). It does not refer to any of the solvents, pH modifiers or adjuvants also contained within a product that contribute to its efficacy.

Biological control is use of a micro-organism, such as a bacteria or virus, or, macro-organisms, such as insect predators or nematodes that are used to control insect pests, weeds and diseases. In this report biologicals which do not require to be authorised are referred to as biological control agents. These are generally macro-organisms such as parasites or predators. Biologicals which do require to be authorised like other pesticides are referred to as biopesticides. Biopesticides are pesticides that are derived from natural materials and include micro-organisms (bacteria, fungus, virus or protozoa) to control pest populations or compounds such as semio-chemicals that cause behavioural changes in the target pest. In previous surveys (before 2015) biopesticides were included in the biological control agent category.

A fungicide is a pesticide used to control fungal diseases in plants.

A herbicide is a pesticide used to control unwanted vegetation (weed killer).

A growth regulator is a pesticide used to regulate the growth of the plant, for example to prevent the crop from growing too tall.

An insecticide is a pesticide used to control unwanted insects. A nematicide is a pesticide used to control unwanted nematodes.

A molluscicide is a pesticide used to control unwanted slugs and snails.

A physical control agent is a substance, preparation or organism designed or used for destroying or controlling pests if their principal mode of action does not involve chemical or biological action.

A seed treatment is a pesticide applied to seed before planting to protect that plant against diseases and pests from the earliest stage of development. The pesticide can be a fungicide, an insecticide or a biological control agent. Information about pesticides applied as seed treatments was only collected for field sown crops, not for transplanted crops. Pesticides applied to transplants in nurseries before going to the grower are recorded in the Protected Edible Crops survey.

In the pesticide tables (see data tables in supporting document), some pesticide treatments may be reported as 'unspecified'. This description was used for occasions where the use of a particular treatment was reported by the grower, but they were unable to provide details of the product used. For these treatments, we are able to provide an area treated but no weight of pesticide used since the exact pesticide is unknown.

Some seed treatments were recorded as 'no information seed treatment'. This description was used for occasions where the grower was unable to confirm whether the seed had received a treatment.

Basic area is the planted area of crop which was treated with a given pesticide or pesticide group, irrespective of the number of times it was applied to that area. Basic areas are not presented anywhere in the report, but their values are used to calculate the percentage of crop treated with a given pesticide or pesticide group.

Area treated is the basic area of a crop treated with a given pesticide multiplied by the number of treatments that area received. These terms are synonymous with "spray area" and "spray hectare" which have appeared in previous reports. For example, if a field of five hectares is sprayed with the same fungicide twice, the basic area is five hectares, and the treated area is ten hectares.

Farmers/growers can apply pesticides to crops by a number of different methods. Multiple pesticides can be applied to a crop in a single tank mix. For example, a crop could be sprayed with two different fungicides and an insecticide at the same time.

In this report, summary data for pesticide formulations including the area treated and weight applied are discussed. Full detail and data tables are available in the Excel supporting document published alongside this report. In the supporting document, data is reported in various formats. For each pesticide formulation (mixture of active substances in a product) the area treated and weight applied is reported (Table 2). Areas and weights for individual active substances are also shown (Table 3). These different formats are provided to satisfy the needs of all data users and allow them to assess pesticide use trends. Some users may be interested in use of pesticide products which contain a number of active substances, thus formulation data would be required. Other users are interested in particular active substances which may be formulated on their own or in combination with other active substances. In addition, both weight and area of pesticide applications are important indicators of changes in use over time. Different pesticides are applied at different dose rates and only by comparing both area and weight can trends in use be elucidated.

It should be noted that some herbicides may not have been applied directly to the crop itself but either as land preparation treatments prior to sowing/planting the crop, or to control weeds at the field margins or inter-row areas.

The June Agricultural Census [9] is conducted annually by the Scottish Government's Rural and Environmental Science Analytical Services (RESAS). The June Agricultural Census collects data on land use, crop areas, livestock and the number of people working on agricultural holdings. For this report the June Agricultural Census was used to draw a sample of farmers growing the relevant crops to participate in the survey.

Throughout this report the term 'census area' refers to the total area for a particular crop or group of crops recorded within the June Agricultural Census. These are the areas which the sample areas are raised to. Please see data and methodology section for details. The June Agricultural Census Form is divided up into different categories which relates to a particular crop or group of crops. These are referred to as 'census categories' throughout this report.

The areas of crops grown can be larger than the total area of crop recorded in the June Agricultural Census. This is due to successional sowings/plantings on the same area of land during the same season. This is referred to throughout the report as multi-cropping. No multi-cropping was encountered during the 2023 survey.

Where quoted in the text, reasons for application are the grower's stated reasons for use of that particular pesticide on that crop and may not always seem appropriate. It should be noted that growers do not always provide reasons; therefore, those presented only reflect those specified and may not reflect overall use.

Due to rounding, there may be slight differences in totals both within and between tables.

Data from the 2021 [3] and 2019 [4] surveys are provided for comparison purposes in some of the tables (see supporting document), although it should be noted that there may be minor differences in the range of crops surveyed, together with changes in areas of each of the crops grown. When comparisons are made between surveys it is important to consider changes in the area of crop grown. In order to take this into account, comparisons have been made on a per hectare grown basis, i.e. the number of hectares that have been sprayed (treated hectares) has been divided by the area of crop grown for each survey, and the weight (kilograms) applied has also been divided by the area of crop grown. This is to enable like for like comparisons between surveys, so that changes in pesticide use patterns are not masked by changes in crop area.

When leaf brassicas are referred to in the text, this includes, Brussels sprouts, calabrese and other brassica crops. Other brassica crops in 2023 include red, white, summer/autumn and winter cabbage as well as cauliflower, kale, kohlrabi, purple sprouting broccoli and savoys (some of which was recorded in the 'other vegetable' census category). Crops encountered in the 'other vegetable' category in the 2023 survey include leeks, celeriac, celery, fennel, parsley, radish, spring onions, squash, asparagus, beetroot, chard, courgette, garlic, parsnips, purslane, radicchio, spinach, onions, podded peas and lettuce. For reporting purposes, the data for leeks (recorded in the 'leeks' category) has also been presented under the 'other vegetable' category.

The average number of applications indicated in the text for each crop is based on the occurrence of a pesticide group on at least 10% of the area grown. The average number of applications is calculated only on the areas receiving each pesticide group and therefore the minimum number of applications is always one. Several pesticides may be applied as a tank mix as part of the same spray event; therefore the average number of pesticide sprays reported is less than the sum of sprays of each pesticide group.

Integrated pest management (IPM): The sustainable use directive and the equivalent retained EU law [10] defines IPM as; "'careful consideration of all available plant protection methods and subsequent integration of appropriate measures that discourage the development of populations of harmful organisms and keep the use of plant protection products and other forms of intervention to levels that are economically and ecologically justified and reduce or minimise risks to human health and the environment. 'Integrated pest management' emphasises the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms."