Summary
This is the fourth 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) and 1994 (Jess et al., 1997). Information on all aspects of pesticide usage was collected from 349 holdings throughout the Province, representing 20% of the total area of arable crops grown. Quantitative data has been adjusted to provide estimates of total pesticide usage. The area of arable crops grown in Northern Ireland in 1996 was 51,119 hectares, representing a 1% reduction to that recorded in 1994 and a 12% reduction to that recorded in 1992.

By comparison with 1994, the pesticide-treated area in 1996 increased by 9% to 268,710 spray hectares, while the quantity of pesticides applied increased significantly by 85% to 449 tonnes. The increase in quantity of pesticides used in 1996 was attributed to increased use of sulphuric acid as a potato haulm desiccant. Increases of 6% and 4% were recorded in the fungicide-treated area and the quantity of fungicide active ingredients applied, respectively, during this period. In 1996 the quantity of herbicides/desiccants used increased by one and a half times that recorded in 1994, with an 11% increase in the area treated with this pesticide group. A considerable increase in the area of arable crops treated with insecticides was observed over the six-year period 1990-1996, with over a two-fold increase to that recorded in 1994. The most notable increase was recorded in the use of pyrethroid insecticides in both treated area and weight of active ingredients applied. While the area of cereals grown remained similar to that recorded in 1994, the insecticide-treated area increased by 92%. A three-fold increase in the area treated with pyrethroid insecticides was recorded. The area of potato crops treated with insecticides increased from 102 in 1994, to 1,295 spray hectares in 1996. Pyrethroid and organophosphorus insecticides individually represented approximately 50% of the insecticide-treated area of potato crops in 1996. The current survey recorded a 79% increase in the area treated with molluscicides, while the weight of mulluscicide active ingredients applied declined by 24% when compared to that recorded in 1994. The area treated with growth regulators increased steadily by 61% in the six-year period 1990 to 1996, while the weight of growth regulator active ingredients applied increased by 18%. In the two year period 1994 to 1996 the quantity and area treated with formulations containing active ingredients from different pesticide groups remained relatively constant. The area of arable crops sown or planted with treated seed was similar to that recorded in 1994, while the weight of seed treatment active ingredients decreased by 40%.

In 1996 regional pesticide usage closely approximated to the areas of arable crops grown in each county. Pesticides were applied to 99% of the total area of arable crops grown in Northern Ireland in 1996, with a mean of 2.5 applications.

Fungicides were applied to 45% of the pesticide-treated area, accounting for 21% 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 5% 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 5% of the pesticide-treated area and 3% of the weight of active ingredients used. Seed treatments applied to arable crops grown in 1996 accounted for 15% of the pesticide-treated area, while only representing 1% of the quantity of active ingredients applied.

Potato crops received 73% of the total weight of fungicides applied and accounted for 54% of the area of arable crops treated with fungicides. Furthermore, applications of herbicides and desiccants to potato crops represented 22% and 87% of the area treated and quantity of this pesticide group applied, respectively. The single most commonly used fungicide active ingredient was mancozeb. In relation to treated area, spring barley accounted for 35% of the herbicide/desiccant-treated area, but only 3% of the weight of active ingredients applied. The most commonly applied herbicide, used exclusively on cereal crops, 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 herbicide/desiccants used. This relative proportion was further diminished by the large quantities of sulphuric acid applied, as a pre-harvest potato haulm desiccant, to a comparatively small area of potato crops. Pyrethroid insecticide active ingredients accounted for 62% of insecticide-treated area of arable crops in 1996. However, organophosphorus insecticides accounted for 77% of the weight of insecticide active ingredients used. Cypermethrin was the most extensively used insecticide active ingredient, accounting for 43% of the insecticide-treated area. The organophosphorus insecticides most frequently used were dimethoate and chlorpyrifos.

A total of 209 products, comprising 131 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 190,392 tonnes of potatoes were stored, on-farm, following the 1996 growing season. This represented a 59% increase when compared with 1994. Ware potatoes accounted for 71% of the total quantity of stored potatoes, seed potatoes 21% and reserved seed 8%. 'Reserved seed', not previously defined, refers to seed potatoes retained for planting in the 1997 growing season. While County Antrim accounted for 48% of all potatoes stores, this represented 78% of all potatoes receiving treatments in storage and 68% of the quantity of pesticides applied. Overall, 20% of stored potatoes received pesticide treatment. An estimated 1,605 kilograms of pesticides were applied to 38,365 tonnes of stored potatoes, giving a treated tonnage of 38,642 including multiple applications. Seven products comprising five active ingredients were recorded in use on stored potatoes in Northern Ireland in 1996. Thiabendazole was the most extensively used active ingredient, in terms of both quantity of active ingredients applied and tonnes of potatoes treated. Approximately 60% of all potatoes in 1996 were stored in barn stores. Overall, 58% of potatoes were stored on-farm in bulk only, while 21% were solely 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