Pesticide usage report: Vegetable crops 2007

Summary

This is the fifth 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) and 2004 (Kearns et al., 2005). Information on all aspects of pesticide usage was collected from 87 holdings throughout the province. Quantitative data have been adjusted to provide estimates of total pesticide usage.

The area of vegetable crops grown in Northern Ireland in 2007 was an estimated 1900 hectares, which represented an 18% increase compared with 2004. There was an increase of 28% in the area of brassica crops grown, with a significant increase of 46% in the area of Brussels sprouts grown. The area of turnips & Swedes decreased by 20% compared with 2004. Carrot and parsnip crops increased by 25% and 87% respectively compared with the area grown during the same period. The total area of celery crops increased by 79% when compared to 2004.

By comparison with 2004, the pesticide-treated area increased by 23%, to 13,909 spray hectares, while the weight of pesticide active ingredients applied increased by 19% to 8.5 tonnes. The average number of spray applications (2.5) remained similar to that recorded in 2004 and 1999. The fungicide-treated area increased by 50%, while the weight of fungicide active ingredients increased by more than two fold. Overall, both the application area and weight of herbicides and desiccants applied increased by 8% and 5%, respectively. Both the treated area and the weight of insecticides applied increased by 23% and 1%, respectively. Applications of organophosphate insecticides decreased by 51% with a corresponding 41% decrease in weight applied. However, the application of azomethine, chloronicotinyl and carbamoyl triazole type insecticides, principally to brassicas, increased. Insecticides were most frequently used to control carrot fly (Psila rosae) on carrot and parsnip crops. However, overall, they were also often applied to control aphids. The area treated with molluscicides and the weight applied increased by 42% and 3%, respectively. An estimated 1,039 hectares of vegetable crops were sown with treated seed. This was a 23% increase compared to 2004 which is in proportion with the increase in the area of vegetable crops grown. In 2007 the proportion of brassica crops sown with treated seed increased but there was a reduction in the area of turnips and swedes sown with treated seed.

Fungicides, applied to 27% of the pesticide-treated area, accounted for 24% of the weight of pesticides applied. Herbicides and desiccants accounted for 35% of the pesticide-treated area and 68% of the total weight of pesticides used. Insecticides, applied to 29% of the pesticide-treated area, accounted for 7% of the total weight of pesticides used. Seed treatments applied to vegetable crops grown in 2007 accounted for 7% of the pesticide-treated area representing 1% of the weight of active ingredients applied. Molluscicides accounted for less than 1% of both the total pesticide-treated area and the weight of pesticides applied to vegetable crops grown.

Brassica crops received 28% of the weight of fungicides applied to all vegetable crops, representing 42% of the area of vegetable crops treated with fungicides. The single most commonly used fungicide active ingredient applied to brassicas was difenoconazole. Carrots and parsnips collectively accounted for 32% of the weight of fungicide active ingredients applied, representing 22% of the area treated with fungicides. The single active ingredient tebuconazole, along with the new formulation azoxystrobin/difenoconazole were the most frequently applied fungicides to these vegetable crops.

Herbicide applications to brassica and carrot crops individually represented 29% 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 carrot crops. Trifluralin was also frequently applied, principally to brassicas.

Carrots and parsnips collectively accounted for 49% of the insecticide-treated area, representing 29% of the weight of insecticide active ingredients applied. Brassicas accounted for 44% and 66% of the insecticide-treated area and weight applied, respectively. Pyrethroids were the most frequently used insecticide active ingredients, particularly lambda-cyhalothrin.

Methiocarb was the only molluscicide applied to vegetable crops and slug control was the only reason for its use. An estimated 83% of all molluscide applications were to brassica crops.

The neonicotinoid insecticide imidacloprid was the most frequently used seed treatment accounting for 36% of the area sown with treated seed and 82% of the weight of seed treatments applied. An estimated 42% of all seed treatments were applied to brassicas and 32% to carrot and parsnip crops.

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