Pesticide Usage Report: Edible Protected Crops 2023

SUMMARY

This is the fifth survey examining pesticide usage practices on edible protected crops (excluding soft fruit) grown under permanent protection in Northern Ireland, providing comparative data to that obtained in the previous surveys in 2015 (Lavery et al., 2016), 2017 (Lavery et al., 2018), 2019 (Lavery et al., 2020) and 2021 (Kirbas et al., 2022). For this survey, a number of different vegetable crops and tomatoes, which are propagated and/or grown under permanent cover of glass or polythene until harvested, are included. Information relating to pesticide use on soft fruit crops is recorded in the pesticide usage report Soft Fruit Crops, 2022 (Kirbas et al., 2023).

Protected crop cultivation is a very minor sector of agricultural production in Northern Ireland and includes a range of crops grown on relatively small areas which receive varying degrees of pesticide application. These factors lead to greater statistical uncertainty associated with the estimates produced and, whilst these data give an indication of pesticide use in this sector, they are less statistically robust than the estimates from the other reports in this series and should be interpreted accordingly. In keeping with the 2021 report, this report contains multiple-cropping areas, where successive crops are produced from the same basic area. This may result in figures which differ from the basic farm level information contained in the farm census.

Data were collected from ten holdings, representing 66% of the total area of edible protected crops grown in Northern Ireland (Table 1). Holdings were selected from information contained in the Northern Ireland Agricultural Census, June 2022 (Anon., 2023) and Basic Payment Scheme returns, 2023. Raising factors have been applied to estimate national pesticide usage from sampled data. Data relating to individual crop types have not been published due to the small cultivation and sample areas and the possibility of identifying growers.

A total of thirteen fungicide active substances including formulated fungicide mixtures were recorded in use on edible protected crops in Northern Ireland in 2023. Cyprodinil/fludioxonil represented 26% of the fungicide-treated area and 7% of the weight of fungicides applied. However, fosetyl-aluminium/propamocarb hydrochloride, which accounted for 4% of the fungicide-treated area, represented 70% of the weight of fungicides applied, primarily on brassica crops during propagation stage for the control of downy mildew. Propamocarb hydrochloride accounted for less than 1% of the fungicide-treated area but 9% of the weight of fungicides applied. (Tables 7 and 8).

There were only two herbicide active substance applied in 2023 which accounted for less than 2% of the total pesticide-treated area and the total weight of pesticides applied. (Tables 7, 8 and 13).

A total of six insecticide active ingredients were recorded in 2023. The tetramic acid insecticide spirotetramat accounted for 76% of the area treated with insecticides, representing 82% of the weight of insecticides applied. The diamide insecticide cyantraniliprole accounted for 7% of the area treated with insecticides and 13% of the weight of insecticides applied.  The pyrethroid insecticide lambda-cyhalothrin accounted for 13% of the insecticide-treated area and 2% of the weight of insecticides applied. (Tables 7, 8 and 12).

Two microbial pesticides were recorded in 2023, Bacillus subtilis and Gliocladium catenulatum, for the control of Botrytis cinerea and damping-off diseases accounted for 6% of the total pesticide-treated area and 8% of the weight of pesticides applied. (Tables 7, 8 and 11-17).

Seed treatments accounted for 4% of the total pesticide-treated area and <1% of the weight of pesticides applied. The seed treatment active substances fludioxonil and metalaxyl-M, were primarily applied to leafy and flowerhead brassica crops, representing 86% of the seed-treated area and 38% of the weight applied. Lettuce, tomatoes and turnips and swedes were the only crops not to receive a seed treatment.

Lettuce crops accounted for the largest growing area of all edible protected crops, although this was principally due to repeat cropping within the basic growing area. Lettuce crops received 76% of all fungicides applied representing 16% of the weight applied. Conversely, leafy and flowerhead brassica crops, which received 21% of all fungicides applied, accounted for 83% of the weight applied. Lettuce crops received an average of 3.4 fungicide, 1.0 herbicide, 1.9 insecticide and 1 biopesticide applications. (Tables 6 and 13).

Commercial edible protected cropping is a relatively specialist area of crop cultivation, extending the natural growing season to provide a continuous supply of crops for retailers. Edible protected crops may also be imported from abroad to augment locally grown crops.

Edible protected crops can be grown on relatively small areas, particularly at propagation stage, but increased space is required to accommodate them as the plants mature. Multi-cropping also allows successive crops to be produced from the same basic area.

Growing crops in permanent glasshouses or polythene tunnels enables the grower to closely monitor and maintain the conditions within. The effectiveness of biopesticides and pollinators can also be maximised within the enclosed environment.  However, increased energy costs and the incidence of pests such as glasshouse whitefly (Trialeurodes vaporariorum) that reproduce rapidly under these conditions can prove problematic within a protected structure and lead to increased pesticide inputs.

Crops that were grown outdoors for part of or all of their life cycle, are recorded in the Outdoor Vegetable Crops in Northern Ireland 2023 report (Lavery et al., 2024).