Pesticide usage on arable crops in Northern Ireland: 2020 survey report

This is the sixteenth survey of pesticide usage practices on arable crops in Northern Ireland. Information on all aspects of pesticide usage was collected from 90 holdings throughout the Province, representing 31% of the total area of arable crops grown. Quantitative data has been adjusted to provide estimates of total pesticide usage.

The total area of arable crops grown in Northern Ireland in 2020 was 36,074 hectares. This represented an increase of 5% compared to that recorded in 2018 but a 42% reduction compared to that recorded in the first pesticide usage survey of the arable sector, in 1990. Approximately 50% of the arable cropping area in 2020 was in County Down, 18% in County Londonderry, 15% in County Antrim, 12% in County Armagh and 5% in County Tyrone. There was no significant area of arable cropping in County Fermanagh.

A total of 307 products, comprising 121 active substances were recorded in use on field crops in this survey compared with 344 products and 134 active substances used in 2018. No fallow, organic, undersown or cover crops were recorded during this survey period. Spring barley, winter barley and winter wheat collectively accounted for 87% of all arable crops grown in Northern Ireland in 2020.

The total weight of pesticides applied to arable crops in 2020 decreased from 122 tonnes of active substances to 107 tonnes, representing a 12% decrease from both 2018 and 2016, respectively. Spring barley represented 35% of the area of crops grown and accounted for 25% of the total area of arable crops treated and 18% of the weight of pesticides applied. Since 2012, the area of spring wheat crops grown decreased by 36% whilst during the same period the area of winter barley crops grown increased by 46%.

Winter wheat accounted for 24% of the area treated with fungicides and 15% of the weight of fungicides applied, whereas spring wheat accounted for <1% of both the fungicide treated area and weight of fungicides applied. Compared with 2018, fungicide applications decreased by 8%, with chlorothalonil, either applied as a single active substance or as a formulation, the most frequently applied to cereal crops, especially spring barley, winter barley and winter wheat.

Herbicide and desiccant applications decreased by 10%. Glyphosate was the most frequently applied, accounting for 18% of all herbicide and desiccant applications and 42% of the weight applied.

Insecticide applications increased by 11% when compared with 2018 and the weight applied increased by 4%. The pyrethroid insecticides esfenvalerate and lambda-cyhalothrin were used extensively on spring barley, accounting for 38% and 54% of the area treated and 12% and 22% of the weight applied, respectively. Conversely, pymetrozine, which accounted for 4% of the insecticide treated-area represented 50% of the weight applied. Some minor use of chlorpyrifos has been recorded on winter barley crops for general insect control, though, it should be noted that, from 31st March 2016, all uses have been revoked except for treatment of brassica crops in peat blocks via gantry-mounted sprayers.

Molluscicide applications increased significantly since the previous reporting period, increasing from 2,002 spray hectares in 2018 to 5,518 spray hectares in 2020, mainly due to an increase of applications to maincrop potatoes. Molluscicide applications to these crops accounted for 67% of the area treated with this pesticide group, with ‘Slugs’ given as the only reason for use. Ferric phosphate was the only mollucisicide recorded in 2020.

Growth regulator applications increased by 2% when compared to 2018. The principal growth regulators used were chlormequat and trinexapac-ethyl which is consistent with previous surveys conducted between 2006 and 2018. Growth regulators were applied primarily to spring barley, winter barley and winter wheat, collectively accounting for 86% of both the area treated with these active substances and the weight applied.

Seed treatment applications increased by 18%, though the weight applied decreased by 85% when compared with 2018. This was primarily due to difficulties determining the weight of ‘unknown seed treatments’ which accounted for 35% of the seed-treated area. In 2018, the combined insecticide and fungicide seed dressing clothianidin/prothioconazole was the most frequently used seed treatment, though it was withdrawn from use in December 2018. In 2020, the phenylpyrrole fungicide seed treatment, fludioxonil, was the most frequently used fungicide, accounting for 45% of the seed-treated area and 38% of the weight of seed treatments applied.

Foliar feeds and adjuvants, although not classified as active substances, are included in this report due to their use in arable crop cultivation and production. It should be noted, however, their use is relatively minor and does not constitute significant treated areas or quantities applied.

Potato crops comprised 10% of the area of arable crops grown in Northern Ireland in 2020, accounting for 23% of the total pesticide-treated area. However, the weight of pesticides applied to potato crops represented 37% of the total weight of pesticides used on all arable crops. The total area of potatoes grown comprised 2% early, 11% seed and 87% maincrop potatoes.

Potato crops accounted for 34% of the area of arable crops treated with fungicides and received 57% of the total weight of fungicides applied. Furthermore, applications of herbicides and desiccants to potato crops represented 18% of both the area treated and the weight applied of this pesticide group, respectively. Potato crops received more pesticide treatments than any other arable crop.

Unfortunately, owing to restrictions imposed by the Covid 19 pandemic, data collected for pesticide application to potatoes, particularly in County Londonderry, was unreliable and insufficient to determine overall estimate for pesticide usage on this crop at a national level. Consequently, latitude should be exercised during data interpretation.

In previous years, data relating to post-harvest potato storage methods and quantities were collected. However, due to the Covid-19 pandemic, it has not be possible to collect these data with any reliability and they have therefore been omitted from this report.