Pesticide usage report: edible protected crops 2015

Summary

This is the first survey of pesticide usage exclusively on edible protected crops (excluding soft fruit) grown under permanent protection in Northern Ireland.  A previous report in 1991, Protected Crops (edible and ornamental), (Kidd, S. L. B., et al 1993), included information on pesticide use on vegetable crops, strawberries and protected ornamental crops.  For this survey, a number of different vegetable crops and tomatoes, which were propagated and/or grown under permanent cover of glass or polythene until harvested, were included.  Information relating to pesticide use on soft fruit crops is recorded in the pesticide usage report Soft Fruit Crops, 2014 (Lavery, M. K., et al 2015).

Protected crop cultivation is a very minor sector of agricultural production in Northern Ireland and includes a range of crops grown on relatively small areas, which receive varying degrees of pesticide application. These factors lead to greater statistical uncertainty associated with the estimates produced and, whilst these data give an indication of pesticide use in this sector, they are less statistically robust than the estimates from the other reports in this series and should be interpreted accordingly.  Data were collected from nine holdings, which represented 20% of the total census area of edible protected crops.  Holdings were selected from information contained in the Northern Ireland Agricultural Census, June 2014 (Anon., 2015) and raising factors have been applied to estimate national pesticide usage from sampled data.  Data relating to individual crop types have not been published due to the small cultivation and sample areas and the possibility of identifying growers.

A total of seven fungicide active substances including formulated fungicide mixtures were recorded in use on edible protected crops in Northern Ireland in 2015.  The carbamate fungicide propamocarb hydrochloride represented 18% of the fungicide-treated area but accounted for 65% of the weight of fungicides applied, exclusively on brassica crops for disease prevention and “damping off in propagation”.  The strobilurin fungicide azoxystrobin was the only fungicide active substance applied to lettuce and tomato crops, exclusively for general fungal disease control.

The only herbicide recorded in use on edible protected crops was the dinitroaniline herbicide pendimethalin, which was applied to parsley, soup celery, soup leeks, spring onions and lettuce crops for general weed control, representing 4% of the total pesticide-treated area and 1% of the total weight of pesticides applied.

Chlorpyrifos, an organophosphorus insecticide and acaricide, was applied exclusively to brassica crops for control of cabbage root fly (Delia radicum).  The area treated with this active substance accounted for 30% of the insecticide-treated area but represented 99% of the total weight of insecticides applied.  This was due to the high rate of application as a drench treatment to brassicas during the propagation stage when the plants were still in module trays.  A formulation of lambda-cyhalothrin/pirimicarb, applied to lettuce crops for general insect control, accounted for 39% of the insecticide-treated area but less than 1% of the weight of insecticides applied.

The soil fungus biopesticide, Gliocladium catenulatum, applied as a drench to the compost in module trays containing brassica plant seeds exclusively for general fungal control, represented 5% of the total pesticide-treated area and less than 1% of the weight of pesticides applied.  Some minor use of the predatory mite Neoseiulus californicus on tomato plants was also recorded but the information provided was deemed unreliable and as such has not been included in the total area treated.

Seed treatments, which accounted for 34% of the total pesticide-treated area but only 1% of the weight of pesticides applied, were applied to all crops with tomatoes being the only exception.  Thiram and thiamethoxam accounted for 39% and 38% of the seed-treated area, representing 31% and 45% of the weight of seed treatments applied, respectively.  Brassica crops accounted for 43% of the seed-treated area but 88% of the total weight of seed treatments applied.  Lettuce crops, which represented 46% of the seed-treated area, accounted for 5% of the total weight applied.  Thiamethoxam was applied to 82% of all treated lettuce seeds.

Tomatoes received the fewest number of pesticide applications of all edible protected crops, consisting of one fungicide and one insecticide application and no seed treatments.  Seeds were germinated in rockwool and were sown from early spring to allow for summer and autumn cropping. 

Lettuce crops received one application each of fungicide, herbicide, insecticide and a seed treatment.  They received the second fewest number of all pesticide applications made to edible protected crops.

Crops which were grown outdoors for part of or all of their life cycle are recorded in the Outdoor Vegetable Crops in Northern Ireland 2015 report (Lavery, M. K. et al., 2016).  Pesticide use on edible protected crops has previously been included in this report category.