Tom Chillcott works in research at Bayer Crop Science. Each year, the company monitors herbicide performance around Europe. This is done in trials, but very importantly through field observations.

Tom was speaking at the Teagasc grass weeds conference last week.

He collects samples from fields across Europe, including Ireland. So, if a farmer or agronomist notices a problem with the efficacy of a product, a sample can be sent to Bayer and tested for herbicide resistance.

Samples come in from all sorts of crops such as rice, soya beans, maize and cereals.

However, clear trends develop. Tom explained that there is a massive disproportion of samples coming in from winter cropping and winter cereals, in particular.

He noted that 73% of weeds affecting winter cereals are blackgrass, ryegrass and bent grasses. He said that ryegrass consistently comes out on top for most countries.

In order to control these weeds, we need to use cultural control methods, along with herbicides.

It’s something that we have to make a real priority

Cultural control methods are becoming more important, he said, as less herbicide modes of action and products are coming on to the market and the ones that are coming on stream need to be protected.

“The cultural practices are going to become more important, but how you manage and use herbicides is going to become a real challenge.

“It’s something that we have to make a real priority. For the last 10 years, we’ve had the luxury of products like Flufenacet, and Mesosulfuron to a certain extent, that have delivered really effective and crop safe controls quite easily in all your crops.”

He noted that this is going to become more difficult.

Looking at a list of currently available products on the market, he said it is likely that we will see a reduction in the rates used due to regulations and that, ultimately, this will impact on the efficacy of these products. The EU’s Farm to Fork Strategy aims to cut the use of pesticides by 50%.

As this happens, resistance will also be likely to build up in certain weeds and herbicides will be less effective as a result.

Tom said that there is a lack of genuinely new modes of action. There are new active ingredients coming, “but a star doesn’t make a team”.

He said we need to aim to use herbicides as efficiently as possible with appropriate rates and tank mixes.

He also stressed that new modes of action are different to active ingredients, so within a mode of action there will be different active ingredients, but the principle of how they work is the same.

Herbicide discovery timeline

  • 1933: First mode of action discovered in 1933.
  • By end of 1960: 10 modes of action discovered.
  • 1960 to 1980: a further 12 modes of action discovered.
  • 1980 to present: rate of discovery has slowed, one mode of action discovered since 1982.
  • Microplastics legislation

    Something that we may not think would affect herbicides are new regulations around microplastics in the EU.

    On 25 September this year, the EU adopted a restriction on the use of intentionally added microplastics. The EU aims to reduce the use of microplastics by 30% by 2030.

    These rules will be introduced gradually. For example, from 17 October this year, microplastics on their own and when intentionally added will not be allowed.

    Loose glitter is an example of this, Tom commented.

    From 17 October 2027, the use of microplastics will not be allowed in rinse-off cosmetic products.

    From 17 October 2028 the use of microplastics in detergents, waxes, polishes and fertiliser products will not be allowed and their use will not be allowed in herbicides from 17 October 2031.

    This means new formulations will be needed for products currently in use.