A new piece of research by Teagasc, presented at the National Tillage Conference last week, shows that the implementation of the EU’s Farm to Fork Strategy, which requires a reduction in pesticide use, will dramatically impact on crop yields.

The strategy calls for a 50% reduction in pesticide use and a 50% reduction in the use of hazardous pesticides, which have been outlined by the EU Commission.

Ireland has nearly achieved the 50% reduction in overall pesticide use, but has not achieved the 50% reduction in hazardous pesticide use.

The study, carried out by Robert McDougall, examines what could happen if a list of fungicides, insecticides and herbicides are cut to 50% rates. The list includes products which are called candidates for substitution. In other words: if something can replace these products then they will be banned. Some products on the list have already come under review and are being withdrawn such as Metribuzin – a herbicide which is commonly used on potatoes in Ireland. More products may be banned as they come up for re-registration.

What products are affected?

Some of the products or active ingredients on the list (see Table 1) will not be familiar to Irish farmers, but others are commonly used. Among the products on the list are lambda-cyhalothrin, which is commonly used to control barley yellow dwarf virus in cereal crops; metconazole and tebuconazole, which are fungicides used on cereals and oilseed rape; and diflufenican and flufenacet – the active ingredients in Firebird Met, an effective herbicide on winter wheat and barley.

Tri-allate is the ingredient in Avadex Factor the only product in Ireland that claims to have a significant impact on blackgrass control. Benzovindiflupyr contained in Elatus Era and difenoconazole contained in beet, potato and vegetable fungicides are all on the list.

How the survey worked

Teagasc surveyed 17 “experts” which included agronomists, crop specialists and researchers who they considered to be well informed on how the reduced rates of this chemistry would impact crop production in Ireland. The respondents were asked how a 50% reduction in product rate would affect crop yields and what could be done to mitigate the impact on yield.

The results

Looking at winter wheat, the survey responses estimated an average yield loss of 15% from the cut in rate of fungicides, a 10% reduction in yield from the cut in insecticides outlined and, in the short-term, a 15% yield loss from the reduced rates of herbicides outlined. In the longer-term, an average yield loss of 30% was estimated from the reduction in herbicides, as the reduced rates would likely lead to resistance build up to the products in use.

IPM

The use of an integrated pest management (IPM) strategy can help to reduce pesticide use and reduce the impact of pesticide loss on crop production.

IPM uses all tools available to control a problem in a crop from cultural control, like delayed sowing or hand rogueing weeds, to using resistant varieties and nutrient management plans to ensure healthy plants.

The survey respondents outlined resistant or tolerant varieties as the top measure that could be used to mitigate the risk of disease and virus on crops and, therefore, mitigate the loss of these fungicides and insecticides.

Changes in sowing dates and crop rotation could be used in order to mitigate the loss of fungicides, insecticides and herbicides.

Decision support systems were outlined as important tools to mitigate the loss of insecticides and fungicides.

Will IPM replace pesticides?

The expert panel were asked to outline how much yield would be impacted if the listed pesticide products were no longer available and IPM was implemented.

It was clear from the expert opinions that they expect there will still be significant yield loss as a result of the loss of this chemistry. Winter wheat yield was estimated to decline by an average of 10% with the loss of the fungicides outlined and the implementation of IPM. The loss of insecticides was expected to result in a decline of 6.3% when IPM was implemented.

In the short term, the use of IPM instead of the use of the listed herbicides was expected to result in a yield decline of 10%. In the longer term, with resistance build-up, this was expected to increase to 20%.

Looking across the survey results, there is no situation where the implementation of IPM results in a return to normal yields. In fact, on spring barley and wheat, IPM was predicted to make no improvement on yield losses when these products are lost. On winter barley the long-term impact on crop yield without the current chemistry was predicted to be a reduction of about 25%, and using IPM techniques this was only reduced to a reduction in yield of about 20%.

IPM tools not yet available

It is clear from these expert opinions that there is an economic penalty from the implementation of the Farm to Fork Strategy.

Many farmers are already implementing some of these measures like delayed sowing and crop rotation, along with using pesticides. However, some of the measures are not available to them.

For example, decision support tools are not available for Ireland. Yes, there is work ongoing and we can use things like weather data to help aid decisions, but there is no tool that a farmer can input data into to tell them when to spray their barley. BYDV tolerance is outlined as the top IPM measure to mitigate BYDV yield loss. BYDV tolerant varieties were available on approximately 44% of the seed available for winter barley this season, but they are not available for all varieties or for other cereals. Spring barley is the biggest crop in Ireland and is a high-risk crop for BYDV. It is at even higher risk if Lambda is taken off the market without an alternative. Also, most of these varieties are tolerant, not resistant.

If we look at the profile of varieties at present, they have poor resistance to a number of diseases. Winter wheat has low resistance to septoria. Only one variety on the current list has a resistance score of seven to septoria. No varieties have scores of eight or nine for the disease. If varieties do come on stream with strong resistance and there are less chemicals available to reduce disease, then they are more likely to develop resistance to the chemistry that’s there. The resistance could be weakened. In order to breed varieties quickly, more tools are needed. Gene-editing, which can speed up the natural breeding process, is currently banned in the EU.

What next?

An economic assessment of the impact of the 50% reduction in pesticides is currently underway by Teagasc. The impact of these cuts were not fully examined previously. Teagasc concluded that more funding is needed for research into cultural control methods, biological controls and other methods of pest mitigation.

Hazardous pesticides

Pesticides can be declared hazardous for a number of reasons. While products are lost from the toolbox, it makes the job more difficult. However, if a chemical is dangerous for the operator to use, then there is a good reason for it being taken off the market. Ensure that you are using appropriate personal protective equipment when using these chemicals and are applying at the correct rates.