Pesticide usage report: Vegetable crops 2011

Summary

This is the sixth survey of pesticide usage on outdoor vegetable crops in Northern Ireland, providing comparative data to that obtained in the previous surveys in 1991, (Jess et al., 1993), 1995 (Kidd et al., 1998), 1999 (Kearns et al., 2002), 2004 (Kearns et al., 2005) and 2007 (Withers et al., 2009). Information on all aspects of pesticide usage was collected from 61 holdings throughout the province. Quantitative data have been adjusted to provide estimates of total pesticide usage.

The majority of vegetable crops grown in Northern Ireland is related to market influences and is grown under contract. In 2011 an estimated 1,567 hectares was grown, which represented an 18% decrease compared with 2007. There was a 35% decrease in the area of leafy and flowerhead brassica crops grown, despite a significant increase of 54% in the area of cauliflower grown. The area of turnip and swede grown increased by 13% when compared with 2007. The area of carrot and parsnip crops grown decreased by 19% and 10%, respectively. The total area of celery crops decreased by 24% when compared to 2007. However, the area of lettuce crops grown during this period more than doubled.

Fungicides, applied to 26% of the pesticide-treated area, accounted for 21% of the weight of pesticides applied. Herbicides and desiccants accounted for 38% of the pesticide-treated area and 62% of the total weight of pesticides used. Insecticides, applied to 27% of the pesticide-treated area, accounted for 15% of the total weight of pesticides used. Seed treatments applied to vegetable crops accounted for 8% of the pesticide-treated area, representing less than 1% of the weight of active substances applied. Molluscicides accounted for 1% of the total pesticide-treated area and less than 1% of the weight of pesticides applied to vegetable crops. Growth regulators accounted for less than 1% of the pesticide-treated area and 1% of the weight of pesticides applied.

By comparison with 2007, the pesticide-treated area decreased by 2%, to 13,617 spray hectares (including 21.32 spha of adjuvants), while the weight of pesticide active substances applied decreased by 14% to 7,289kg (including 2.89 kg of adjuvants). The average number of spray applications (2.5) remained similar to that recorded in 2007, 2004 and 1999. The fungicide-treated area decreased by 8%, while the weight of fungicide active ingredients decreased by 27%. Overall, the application area of herbicides and desiccants applied increased by 6%, however the weight applied decreased by 21%. The insecticide-treated area decreased by 10%, however the weight of insecticide active substances applied increased by 89%. This was due to applications of garlic extract to turnip and swede crops for cabbage root fly and turnip fly. The application of azomethine and chloronicotinyl insecticides, principally to brassicas, increased. Two groups of insecticides, carbazate and ketonole, were applied for the first time. Insecticides were most frequently applied to control aphids, principally on leafy and flowerhead brassica crops. However, they were frequently also used to control carrot fly (Psila rosae) on carrot and parsnip crops. The area treated with molluscicides decreased by 13% and the weight applied increased by 3%. An estimated 1,121 hectares of vegetable crops were sown with treated seed. This was an 8% increase compared to 2007. This was mainly due to an increased use of carrot and parsnip treated seed. However, due to a reduction in the use of leafy and flowerhead brassica treated seed, the weight of seed treatment active substances decreased by 77%. Growth regulators were applied for the first time, exclusively to parsnip crops to delay flowering.

Leafy and flowerhead brassica crops received 33% of the weight of fungicides applied to all vegetable crops, representing 39% of the area of vegetable crops treated with fungicides. The single most commonly used fungicide active substance applied to this crop was difenoconazole. This was mostly for general fungal control. Carrot and parsnip crops collectively accounted for 41% of the weight of fungicide active substances applied, representing 39% of the area treated with fungicides. The single active ingredient metalaxyl-M was the most frequently applied fungicide, mainly for cavity spot and general fungal control.

Herbicide applications to carrot crops represented 33% of the herbicide-treated area and 30% of the weight of herbicides applied. Leafy and flowerhead brassicas accounted for 22% of the herbicide-treated area and 28% of the weight of herbicides applied. Linuron was the herbicide active ingredient most frequently applied to vegetable crops, particularly to carrot crops for general weed control. Metazachlor and glyphosate (during ground preparation) were also frequently applied, principally to leafy and flowerhead brassicas.

Carrot and parsnip crops collectively accounted for 46% of the insecticide-treated area, representing 22% of the weight of insecticide active substances applied. Leafy and flowerhead brassicas accounted for 38% and 31% of the insecticide-treated area and weight applied, respectively.  Due to the use of garlic extract, turnips and swedes represented 10% of the insecticide-treated area and 43% of the weight of pesticides applied. Pyrethroids were the most frequently used insecticide active substances, particularly lambda-cyhalothrin on carrot and parsnip crops.

Applications of the molluscicide ferric phosphate to lettuce crops for slug control, represented 50% of the molluscicide-treated area and 55% of the weight of molluscicides applied. Methiocarb, applied to turnip and swede crops also for slug control, accounted for 47% of the molluscicide-treated area and 42% of the weight of molluscicides applied.

The pyrethroid insecticide tefluthrin was the most frequently applied seed treatment, accounting for 38% of the area sown with treated seed and 56% of the weight of seed treatments applied. An estimated 39% of all seed treatments were applied to carrot crops, 20% to turnip and swede crops and 15% to parsnip crops.

For further information on this work please contact: Pesticide usage monitoring group