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Throwback: control of septoria and pesticide resistance in Denmark

Get an overview of the past year's publications on combating septotia, anti-resistance strategies, and an overview of the pesticide resistance picture in Denmark.

[Translate to English:] Foto: Colourbox

Summer is upon us. This does not mean that the research has come to a stop here - on the contrary. The fieldwork is busy, the experiments too, and not least the laboratories. And why not celebrate summer with a look back at some of the research we have been doing over the past year?

We start with a look back at research that is still of utmost relevance, especially at this time of year. Namely, research into the control of septoria as well as a look at pesticide resistance and weeds in agricultural fields.

Risk models may reduce the use of fungicides against septoria

Risk models for diseases in crops can help farmers when deciding when to use fungicides. It is especially important in relation to the control of septoria in wheat. 

“The need for combating septoria in wheat varies considerably from year to year and from place to place. The disease is primarily driven by so-called moisture events, i.e. rain, dew or high humidity from the elongation of the wheat to the beginning of grain filling,” explains senior researcher Lise Nistrup Jørgensen from the Department of Agroecology at Aarhus University.

The researchers tested two models that show whether fungicide treatment is needed.

Read much more about the results for the two models here.

Anti-resistance strategies are important in the fight against septoria

Fungicide resistance in septoria in winter wheat is spreading according to a very specific pattern in Europe. The pattern was discovered during studies of samples from different northern European countries. Samples from Denmark and Sweden showed that it is through the last approx. 10 years has been a major increase in resistance to the most common fungicides.

The pattern shows at the same time that the resistance is moving from west and slowly to east.

"Mostly the resistance starts in Ireland or the UK, because the weather conditions there are completely optimal for the fungus. The climate there is very humid and favourable for Septoria, and also the Irish farmers use more fungicide than the Danish. In a previous project we have had experiments in many different countries, and we discovered the gradient from west to east (Read more about the project here). That result was confirmed by our new measurements in the Baltic countries, where resistance has gradually begun to show itself, while we have seen a greater degree of resistance further west,” explains Thies Marten Heick.

Even though new products come on the market from time to time, there is still a great risk that resistance to new agents will also build up. The way forward are anti-resistance strategies.

”We simply need to think in terms of anti-resistance strategies from the very beginning, so we can ensure that a resistance to new fungicides is not quickly built up. We hope that with these research projects we can shed some light on how important the anti-resistance strategies are, so that we can continue to fight Septoria in wheat in the future,” says Thies Marten Heick.

Mapping of pesticide resistance

Septoria is not the only thing causing problems for farmers. Weeds are one of the major causes of yield losses. And pesticide resistance is a growing problem for farmers around the world.

In a note to the Danish Environmental Protection Agency, we have mapped the development of resistance in the most common weed species, fungi, and pests in Denmark in relation to the marketed herbicides, fungicides and insecticides. 

The development in resistance shows a picture of more widespread pesticide resistance in several species combined with limited possibilities in relation to the use of pesticides.

"Therefore, it is very important that we try to prevent resistance, and the best way we can do that is by applying measures that reduce the pressure of pests in accordance with the principles of IPM (ed: Integrated Pest Management),” Says Solvejg K. Mathiassen, who along with her colleagues names a number of proposals for resistance prevention.

Read more here