Summary
This is the fifth survey of pesticide usage practices conducted in the arable sector in Northern Ireland, providing comparative data to that obtained in the previous surveys in 1990, (Jess et al., 1992), 1992 (Jess et al., 1995), 1994 (Jess et al., 1997) and 1996 (Jess et al., 2000). Information on all aspects of pesticide usage was collected from 333 holdings throughout the Province, representing 19% 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 1998 was 53,039 hectares, representing a 4% increase to that recorded in 1996. During this period, the area of crops treated with pesticides also increased by 16% to 308,881 spray hectares. The most notable increases were recorded in the use of molluscicides (161%), insecticides (68%) and growth regulators (40%). Increased use of fungicides and herbicides was consistent with the overall increase of pesticide use, while seed treatments declined by 7%. Application of molluscicides to oilseed rape crops contributed significantly to the overall increase in the use of this pesticide type. However, the use of methiocarb on maincrop potatoes also increased more than six-fold. Pyrethroid insecticides, applied principally to cereal crops, particularly spring and winter barley and winter wheat, accounted for the recorded increase in insecticide use. The principal active ingredients recorded from this insecticide group included, cypermethrin, lambda-cyhalothrin and zeta-cypermethrin. The use of insecticides containing organophosphate or carbamate active ingredients declined by approximately 45%. With exception of the formulation of 2-chloroethylphosphonic acid/mepiquat chloride, the use of growth regulators on spring and winter cereals increased substantially. The total quantity of pesticides applied to arable crops remained relatively unchanged at 449 tonnes of active ingredients.

During 1998 regional pesticide usage was related to the areas of arable crops grown in each county, although the pesticide-treated area in County Tyrone was proportionately lower when compared with the other counties. Pesticides were applied to 99% of the total area of arable crops grown in Northern Ireland in 1998 with a range of 1.0 – 9.0 applications depending on pesticide group and crop type.

Fungicides were applied to 45% of the pesticide-treated area, accounting for 20% of the total quantity of pesticides used. Herbicides and desiccants were applied to 30% of the pesticide-treated area, representing 75% of the total quantity of pesticides used. Insecticides accounted for 7% of the pesticide-treated area of arable crops, representing less than 1% of the weight of pesticides used. Molluscicides and mixed activity pesticide treatments represented less than 1% of both area of application and quantity of pesticides used. Growth regulator usage accounted for 6% of the pesticide-treated area and 3% of the weight of active ingredients used. Seed treatments applied to arable crops grown in 1998 accounted for 11% of the pesticide-treated area, while representing only 1% of the quantity of active ingredients applied.

Potato crops accounted for 53% of the area of arable crops treated with fungicides and received 74% of the total weight of fungicides applied. Furthermore, applications of herbicides and desiccants to potato crops represented 18% and 85% of the area treated and quantity of this pesticide group applied, respectively. The single most commonly recorded fungicide active ingredient was mancozeb, used primarily in maincrop potatoes to control blight (Phytophthora infestans). Spring and winter barley crops accounted for 53% of the herbicide/dessicant-treated area, but only 8% of the weight of active ingredients applied. The most commonly applied herbicide, used exclusively on cereal crops, principally spring barley, was metsulfuron-methyl. Owing to the low application rate for this active ingredient, the quantity applied represented less than 1% of the total quantity of herbicides/desiccants used. This relative proportion was further diminished by the large quantities of sulphuric acid applied, as a pre-harvest potato haulm dessicant, to a comparatively small area of potato crops. A decline in the use of organophosphorus insecticides on arable crops resulted resulted in this group accounting for only 8% of the insecticide-treated area in 1998. Pyrethroid insecticide active ingredients accounted for 85% of the insecticide-treated area of arable crops but, owing to low application rates associated with this pesticide group, represented less than 8% of the weight of insecticide active ingredients applied. Lambda-cyhalothrin was the most extensively used insecticide active ingredient, primarily on spring barley, winter barley and winter wheat crops for the control of aphids, accounting for 36% of the insecticide-treated area. The organophosphorus insecticides most frequently used were dimethoate and chlorpyrifos.

Cultivation of pea and bean crops were recorded for the first time in 1998.

A total of 241 products, comprising 114 active ingredients, were recorded in use on field crops in the survey.

In addition to information concerning field applications of pesticides to crops, data relating to post-harvest/storage treatments applied to farm stored potatoes were collected. It was estimated that 162,608 tonnes of potatoes were stored, on-farm, following the 1998 growing season. This represented a 17% decrease when compared with 1996. Ware potatoes accounted for 68% of the total quantity of stored potatoes, seed potatoes 24% and reserved seed for planting in 1999, 6%. County Antrim accounted for 34% of all potatoes stored and of all potatoes receiving treatments in storage and 72% of the quantity of pesticides applied. Overall, 9% of stored potatoes received pesticide treatment. An estimated 1.24 tonnes of pesticide active ingredients were applied to 14,051 tonnes of stored potatoes, including multiple applications. Six active ingredient formulations were recorded in use on stored potatoes in Northern Ireland in 1998. Approximately 73% of all potatoes in 1998 were stored in barn/modified barn stores. Overall, 57% of potatoes were stored on-farm in bulk, while 32% were stored in boxes.

A full list of published reports is available together with abstracts from other relevant published work.

For further information on this work please contact:

Pesticide Usage Survey Group
Agri-food and Biosciences Institute
Newforge Lane
Belfast BT9 5PX

Email: pesticide.science@afbini.gov.uk
Tel: +44 (0)28 90 255689
Fax: +44 (0)28 90 255035