What the tillage sector needs to manage with reduced pesticide use
More resistant varieties, changes in sowing dates and crop rotations, along with the need for additional decision support services are just some of the mitigation measures the Irish tillage sector must adopt to overcome the challenge of reduced pesticide usage.
Addressing the Teagasc National Tillage Conference on January 29, Robert McDougall, a researcher with Teagasc Crop Science, Oak Park, explored the topic of: ‘What do experts think the impact of pesticide use reduction on Irish tillage farming will be?’
Beginning his presentation with an overview of the EU’s Farm to Fork Strategy, which necessitates a 50% reduction in pesticide usage, including a 50% reduction in the use of ‘more hazardous’ substances, Robert McDougall told those gathered that existing data as to what impact this might have on Irish tillage farms is limited, and international data cannot be relied upon to inform the impacts for Ireland.
Robert McDougall, pictured above, presented on: ‘What do experts think the impact of pesticide use reduction on Irish tillage farming will be?’ at the Teagasc National Tillage Conference on January 29.
To quantify this impact, he said: “Replicated field trials would be ideal, but these are time and resource intensive. Instead, we looked to tap an untapped data resource – the knowledge of experts.
“17 experts were recruited from throughout the Irish tillage sector and anonymously surveyed about the impacts meeting the targets may have on yield in wheat, barley and oats, pesticide resistance and current management versus integrated pest management (IPM) practices. After the first round of the survey, we summarised the group response and provided it as feedback to the participants, allowing them to revise their answers if they thought necessary. This iterative process, often called a Delphi survey, is a way of adding a level of objectivity to data derived from expert opinion.”
Using winter wheat as an example, Robert McDougall explained: “The panel expected winter wheat yields to decline by 15% on account of lower fungicide use and 10% due to lower insecticide use.
"Herbicide reductions were examined in both the short term and long term (over a 5 and 10 year period), with the panel predicting yield reductions of 15% and 30%, respectively, if current management techniques were maintained.”
Robert McDougall also presented data on the expert panel’s top ranked IPM measures. These were:
- For fungicide reductions: Resistant/tolerant cultivars; changes in sowing dates; and changes in crop rotations;
- For insecticide reductions: Resistant/tolerant cultivars (to Barley Yellow Dwarf Virus); changes in sowing date; and decision support services / monitoring;
- For herbicide reductions: Changes in crop rotations; decision support services / monitoring; and changes in sowing dates.
While the application of these techniques was predicted to reduce the impacts of using less pesticide, those impacts were not mitigated entirely, as shown in Figure 1.
Figure 1: Impacts with additional IPM (winter wheat)
Although acknowledging the above data was just expert opinion, and regional specific, farm scale evaluation trials would be required to understand the full impact of pesticide reductions, he suggested that the results provide a starting point.
“Strategically, we need to now focus on accelerated development of the key mitigation measures; Resilient varieties, cultural control strategies for weed mitigation, and better provision of tailored decision support services which allow for more precise and integrated pesticide use. While the experts didn’t think these measures would be a panacea for the expected yield losses, if they become more of a mainstay of pest management in a lower pesticide future then there’s the potential they may be able to have a much greater impact” he concluded.
Robert McDougall also appeared on this week's Tillage Edge podcast, where he discussed the above in more detail.
Listen in below:
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