Pesticide Usage Report: Arable Crops 2018

SUMMARY

This is the fifteenth survey of pesticide usage practices on arable crops in Northern Ireland.  Information on all aspects of pesticide usage was collected from 203 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 2018 was 34,398 hectares.  This is the lowest cropping area recorded since pesticide usage records began in 1990.  This represented a decrease of 9% compared to that recorded in 2016 and a 44% reduction compared to that recorded in the first pesticide usage survey of the arable sector, in 1990.  Approximately 38% of the arable cropping area in 2018 was in County Down, 26% in County Londonderry, 16% in County Antrim, 12% in County Tyrone and 8% in County Armagh.  This distribution is similar to that recorded during 2006 - 2014.  There was no significant area of arable cropping in County Fermanagh. 

A total of 344 products (including 1 adjuvant and 4 foliar feeds), comprising 121 active substances were recorded in use on field crops in this survey compared with 366 products and 134 active substances used in 2016.  No fallow, organic or cover crops were recorded during this survey period.  Undersown oats was the only arable crop not to receive any pesticide treatments.  Spring barley, winter barley and winter wheat collectively accounted for 78% of all arable crops grown in Northern Ireland in 2018.  The total weight of pesticides applied to arable crops in 2018 increased slightly to 122 tonnes of active substances, representing a 0.2% increase from 2016 compared with a 3%, 8% and 11% reduction when compared with 2014, 2012 and 2010, respectively.

Spring barley represented 43% of the area of crops grown (table 3) and accounted for 31% of the total area of arable crops treated (table 5) and 25% of the weight of pesticides applied (table 6).  Since 2012, the area of spring wheat crops grown decreased by 47% whilst during the same period the area of winter barley crops grown increased by 9%.  Winter wheat accounted for 25% of the area treated with fungicides and 16% of the weight of fungicides applied, whereas spring wheat accounted for both 1% of the fungicide treated area and weight of fungicides applied.    Compared with 2016, fungicide applications decreased by 5%, 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 5%.  Glyphosate was the most frequently applied, accounting for 21% of all herbicide and desiccant applications and 41% of the weight applied.  The active substance ethametsulfuron-methyl, used for general weed control in winter oilseed rape crops, is not approved for use in the UK but does have approval in the Republic of Ireland.

Insecticide applications decreased by 19% when compared with 2016 and the weight applied decreased by 36%.  The pyrethroid insecticides esfenvalerate and lambda-cyhalothrin were used extensively on spring barley, accounting for 51% and 46% of the area treated and 31% and 42% of the weight applied, respectively.  Some minor use of chlorpyrifos has been recorded on spring barley crops though, it should be noted that, from 31^st March 2016, all uses have been revoked except for treatment of brassica crops in peat blocks via gantry-mounted sprayers.

Molluscicide applications decreased by 26% since the previous reporting period.  Primarily, molluscicide applications were to control slugs in maincrop potatoes accounting for 59% of the area treated with this pesticide group.  Ferric phosphate and metaldehyde were the only mollucisicides recorded in 2018.

Growth regulator applications decreased by 7% when compared to 2016.  The principal growth regulators used in 2018 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 92% of the area treated with these active substances and 93% of the weight applied.

Seed treatment applications decreased by 14% and the weight applied by 33% when compared with 2016.  The combined insecticide and fungicide seed dressing clothianidin/prothioconazole was the most frequently used seed treatment, primarily on winter barley and winter wheat.  The UK-authorised plant protection product containing these active substances has been withdrawn with a phased-withdrawal period of 19 September 2018 for sale and distribution and 19 December 2018 for storage, disposal and use.

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 11% of the area of arable crops grown in Northern Ireland in 2018, accounting for 22% of the total pesticide-treated area.  However, the weight of pesticides applied to potato crops represented 36% of the total weight of pesticides used on all arable crops.  The total area of potatoes grown comprised 3% early, 10% seed and 87% maincrop potatoes.  Potato crops accounted for 35% of the area of arable crops treated with fungicides and received 52% of the total weight of fungicides applied.  Furthermore, applications of herbicides and desiccants to potato crops represented 15% of the area treated and 26% of the weight applied of this pesticide group.  Potato crops received more pesticide treatments than any other arable crop (Table 7).

In addition to information concerning field applications of pesticides to potatoes, data relating to post-harvest storage methods and quantities were collected.  Since arable surveys began in 1990, the estimated total quantity of potatoes stored annually in Northern Ireland has decreased significantly, by 76% (Table 42). In addition, the proportion of stored potatoes receiving pesticide treatments has also declined from approximately 20%, by weight in 1996, to 4% in 2016.

As in 2014, there were no post-harvest/storage treatments applied to farm-stored potatoes during this survey.  It was estimated that 46,161 tonnes of potatoes were stored on-farm, following the 2018 growing season which represented a 31% decrease compared with 2016.  County Down accounted for 58% of all potatoes stored with Londonderry accounting for a further 25%.  Ventilated barn stores and refrigerated cold stores were the most commonly used methods of storage.

There have been a number of new active substances and formulations recorded during this survey period.  Chlorothalonil/fluxapyroxad was applied to winter barley for fungal control and cymoxanil/propamocarb hydrochloride and oxathiapiprolin were used on potatoes, primarily for potato late blight (Phytophthora infestans).