Pesticide usage report: Grassland and fodder crops 2017

SUMMARY 

This is the eighth survey examining pesticide usage practices on grassland and fodder crops in Northern Ireland, providing comparative data to that obtained in the previous surveys in 1989 (Jess et al., 1992), 1993 (Jess et al., 1995), 1997 (Jess et al., 2000), 2003 (Withers et al., 2005), 2005 (Withers et al., 2007), 2009 (Withers et al., 2010) and 2013 (Withers et al., 2014).  Information on all aspects of pesticide usage was collected from 276 grazing, 47 arable silage, 20 fodder maize and 25 other fodder crop holdings throughout the Province, representing 2.7% of the total area of grassland and fodder crops grown.  Quantitative data have been adjusted to provide estimates of total pesticide usage.  The total area of grassland and fodder crops grown in Northern Ireland in 2017 was an estimated 1,185,337 hectares.

Overall, the area of grassland and fodder crops grown in 2017 decreased by 9% when compared to 2013.  The area of established grassland crops decreased by 14% throughout this period.  The area of sown crops increased from 23,190 hectares to 80,567 hectares.  This was primarily due to the inclusion of all grass reseeds up to five years old.  The area of fodder crops grown in Northern Ireland in 2017 decreased by 12% compared to that recorded in 2013.  This was due to the decrease in fodder maize production.  A fourth cut of silage was recorded for the first time in 2005 and this recurred in 2009 and 2013.  During 2017 the area of fourth cut silage decreased by 52% when compared to the previous survey.

The area of grassland and fodder crops receiving pesticide treatment increased by 19% when compared to that recorded in 2013.  A total of 99 tonnes of pesticide was applied to 144,772 spray hectares of grassland and fodder crops during 2017.  This represented a 12% decrease in the weight of pesticides applied compared to 2013.  A total of 119 products comprising 75 active substances were recorded in use during this survey. Herbicides accounted for 90% of the pesticide-treated area, representing 96% of the weight of pesticides applied.  Insecticides accounted for 1% of the treated area and less than 1% of the weight of active ingredients applied.  In 2013, the weight of insecticide active substances applied increased from 176kg to 10,375kg when compared with 2009.  This was principally due to increased applications of the organophosphate chlorpyrifos to first cut silage to control leatherjackets.  It should be noted, however, during this survey period there was no approval for use of chlorpyrifos on grassland or arable silage crops.  A total of 6kg of insecticide active substances were applied to arable silage and grass reseed areas in 2017.  Fungicides, growth regulators and seed treatments collectively accounted for the remainder of the total pesticide usage and were applied to arable silage crops, undersown arable silage crops and reseeded grass areas.  No molluscicide use was recorded during this survey.

The area of established grassland crops treated with pesticides increased by 22% when compared to the 2013 survey.  This was mainly due to increased areas of enclosed grazing and rough grazing and subsequent treatment for docks (Rumex spp.) and rushes (Juncaceae spp.).  Correspondingly, the weight of active substance applied to established grassland crops increased by 26%.  Pesticide usage on sown grassland crops increased by 10% when compared with 2013, however, the weight of active substances applied decreased by 19%.  The area of fodder maize sown decreased by 28% whilst the area of other fodder crops sown increased by 40%.  The pesticide-treated area of fodder crops decreased by 18% from 7,040 spray hectares (spha) to 5,802 spha and the weight of active substances applied decreased by 29%.

In keeping with data from previous years, herbicides remained the most extensively used pesticide type on grassland and fodder crops.  The use of herbicides decreased by 32% between 2005 and 2009 but increased by 20% between 2009 and 2013.  This trend continued when comparing 2013 with 2017 with a 36% increase in the area treated with herbicides and a 30% increase in the weight of active substances applied.  The active substance triclopyr was the most frequently-used herbicide (in formulation with aminopyralid, clopyralid and fluroxypyr), ranked by treated area (spha).   MCPA was the most frequently-used herbicide, ranked by weight applied (kg).  An estimated 52% (24,483 spha) of first-cut grass silage received herbicide treatments for control of docks (Rumex spp.) with a further 15% (6,801 spha) receiving treatments for control of chickweed (Stellaria spp.).  ‘Docks and chickweed’ combined was given as the reason for an additional 13% of herbicide treatments to first-cut grass silage crops.