Alternatives to pesticides are a central focus

Alternatives to pesticides are a central focus at Agroscope

Nothing works without plant protection, because it guarantees the quantity and quality of yields in cereal, fruit and vegetable cultivation, as well as in all other agricultural crops. Now Agroscope too is contributing information on this highly topical issue. Eva Reinhard, Head of Agroscope, explains what research has already achieved and what it may achieve in future.

We all like to eat nice-looking, healthy fruit and vegetables. And we also want them to be grown on healthy, pesticide-free soils. Why doesn’t this work?

EVA REINHARD: The fruit and vegetables we produce are healthy, and things should stay that way. But if we over-pollute the soil and groundwater, this won’t be so easy for future generations. The challenge is to adapt farming production methods so that we can grow and harvest sufficient food with minimum harmful effects on the environment due to plant protection products or synthetic fertilisers.

Why can’t we do this today?

To put it a bit more boldly: the living organisms – ranging from harmful bacteria to insect pests such as the cherry vinegar fly – that attack our fruit and vegetables like them just as much as we do. And the potatoes, apples or carrots that we cultivate are in competition with the plants that would naturally grow in the soil. To make sure there is enough left over for us humans, we have to take various precautions. However, we only resort to synthetic plant protection products once all other measures have been exhausted.

Under damp weather conditions, potatoes can suffer from late blight. What is research doing?

Late blight is the most important disease in potato growing and large volumes of fungicides are used to control it. Potato breeders have been working on this for many years. However, robust new potato varieties have not yet taken off compared with established varieties on the market, due to shortcomings in cultivation or tuber properties and on account of consumer preferences. Agroscope has studied genetically modified (GM) potatoes of the popular variety Désirée. In contrast to the original variety, these were resistant to the blight pathogen and didn’t need to be sprayed. It’s just that we’re faced with conflicting objectives: consumers do want pesticide-free products, but they’re not yet prepared to accept genetically modified plants.

‘We only resort to synthetic plant protection products once all other measures have been exhausted.’

Don’t farmers often spray fungicides for late blight too early?

From a financial perspective, farmers can’t afford to have a crop failure. So they hope to mitigate this risk by treating early. Agroscope was able to show that the negative environmental effects are reduced if early spraying is avoided and infestation forecasts and damage thresholds are followed consistently. To help producers determine the best time to apply the necessary plant protection treatments, Agroscope has been developing forecasting models for over 15 years; for potato producers, for example, there is the forecasting model PhytoPRE. Producers can download this digital application onto their mobile phones. It ensures that fungicides in potato growing are deployed to maximum effect and only at the last moment.

Nevertheless, farmers are often pilloried as scapegoats for polluting the soil and groundwater that provide crucial supplies of drinking water.

Synthetic plant protection products are biologically active substances. If they end up in the wrong place, they can harm living creatures that would actually be useful. Farmers grow cereals, vines, cabbage or potatoes and many other crops in open fields. Some of the pesticides applied are dispersed into the environment. For example, they are washed out by rain and leach into nearby watercourses, sometimes in excessive concentrations. And this must be avoided at all costs.

How is Agroscope helping to ensure that we can continue to rely on clean, pesticide-free drinking water in the future?

Our current work programme for 2018–21 shows that we are making a major contribution to the National Action Plan on Plant Protection Products: over 50 of our 117 research projects come into this area. The overarching objective is to reduce the overall use of plant protection products, especially products with a high risk potential. However, I don’t like to make too strong a distinction between different groups of plant protection products. Basically, all of the products applied are intended to repel or eliminate unwanted living organisms. So the development of direct and indirect alternatives to synthetic plant protection products is a top priority for Agroscope. In the area of preventive, indirect measures, we are breeding new disease-resistant varieties, developing tests and instruments to detect pests before they cross national boundaries, and optimising growing methods to promote beneficial insects or to refine tried and tested crop rotation systems in arable farming. As already mentioned, we are providing farmers with decision-making support by developing early warning and forecasting systems and setting damage thresholds. Further research work is being carried out in the area of non-chemical control. For example, the netting of fruit trees helps to avoid hail damage; unblemished fruit is less susceptible to fungal attack and has a longer shelf life. We are also working in the area of indoor solutions and closed circuits, e.g. in glasshouses. In short, there is no one miracle solution that will allow us to dispense with plant protection products. Rather, there is a range of measures which, when combined, will lead to a noticeable reduction in the application of synthetic products.

‘At Agroscope, the development of alternatives to plant protection products is a top priority’.

Recent figures from the Federal Office for Agriculture (FOAG) show that sales of synthetic plant protection products, and especially of weed killers, have fallen by 29% since 2008. How was this possible?

On the one hand, I attribute this to the alternative methods that have been developed by research in recent years and are being applied today in farming practice. For example, Swiss farmers are now using mechanical weed control much more often. This is being done not only by hand, but also by robots that make the farmers’ work easier. In addition, farming has adapted its production methods and is increasingly using cultivation systems that reduce weed pressure or contribute to biodiversity by using native weeds. For example: in the past there was virtually no vegetation in between the vines in vineyards. Today we know that certain companion plants enrich biodiversity and – provided the weeds don’t emerge too strongly – can even help to reduce pest pressure by providing new habitat for beneficial insects. On the other hand, public debate has probably led to today’s farmers thinking twice about whether the use of synthetic plant protection products is really necessary.

Back to the sales of synthetic plant protection products: it is striking to note that there has been no reduction in fungicides, bactericides, insecticides or acaricides. What is research doing in these areas?

As part of the development of Integrated Production, Agroscope developed efficient methods of biological and biotechnical control for mites and insects in the 1970s, ’80s and ’90s that are still in use today. Even today, predatory mites still play a crucial role in ensuring that fruit and wine growers hardly need to use any acaricides. Also in fruit and wine growing, the sexual confusion method has shown good effects against certain pests, with the result that – especially in vines – growers need to use very few or even no insecticides. Other pests such as aphids, plant lice and various fly species require further research to guarantee yields and quality without the use of insecticides.

Last year’s summer was hot and very dry. Because fungi and bacteria are less able to reproduce under these conditions, there was less use of fungicides. In warm and wet years, however, fungi and bacteria are able to multiply explosively. The most effective method against fungal and bacterial diseases is the breeding of resistant varieties. In recent years, Agroscope has bred many promising, fungus-resistant varieties such as the grapes Divico and Divona, the apricot variety Lisa, the Rustica and Galiwa apple varieties and many wheat varieties. The apricot variety Mia, the apple Ladina and the pear Fred^® are tolerant to bacterial diseases. Agroscope is very efficient in this field of research, thanks in part to multiple collaborations with Swiss universities and foreign institutes such as the French INRA.

According to FOAG statistics, use of the controversial product glyphosate has fallen by 45 percent. Should this active substance be banned?

I am very critical of strategies aimed at banning one active substance after another without effective alternatives being available. From a toxicology perspective, glyphosate is not a high-risk plant protection product. The problem is that it is extremely effective as a herbicide, so farming uses it in phenomenal quantities. If individual active ingredients are used in excessive quantities, resistance develops – as is the case with glyphosate. Synthetic plant protection products should only be used as a last resort in a targeted and site-appropriate manner.

Are there any plant protection products with equivalent effect that could replace glyphosate?

As yet, there is no product that works as broadly as glyphosate. There might be combinations of herbicides with an action equivalent to that of glyphosate. But I doubt that the environmental effects would be any more positive. Thanks to alternative cultivation methods, farming has been able to reduce the use of herbicides in recent years. However, research in this area continues. I doubt we’ll ever be able to manage entirely without herbicides. Climate change is constantly presenting us with new challenges. We will have to deal with plants and animals that are new to Switzerland. It will always take us time to get to grips with these by adapting production systems, and in that time we are likely to be dependent on synthetic plant protection products.

‘There’s no such thing as THE miracle solution. Rather, there is a range of measures which, when combined, will lead to a noticeable reduction in synthetic plant protection products.’

Wouldn’t organic farming be the most logical solution to keep our soil and groundwater free of pesticide residues?

Switzerland has learned a great deal from organic farming and integrated it into conventional production. As a matter of principle, I don’t want to differentiate between production methods and label one as good, the other as bad. As a research institution, Agroscope adopts a neutral approach and takes the best from each cultivation method. I am delighted that conventional farmers are increasingly using products that have been approved for organic farming. It is interesting to note that over 40 percent of the plant protection products sold in Switzerland can already be used in organic farming, even though organic farmers account for less than 40 percent of Swiss crop production.

The plant protection products used in organic farming generally have a lower risk potential than many synthetically manufactured products. However, this often means that they have to be sprayed more frequently and in larger quantities. This increases the workload for farming families, as well as the energy input. I am an advocate of holistic system analysis. In other words, I find it more effective to evaluate production systems on the basis of a life cycle assessment rather than the toxicity of individual active substances used.

‘As a research institution, Agroscope adopts a neutral approach and takes the best from each cultivation method.’

What contribution can consumers make to reducing the use of plant protection products?

In 2018, the renowned journal Science published a study in which Agroscope had a crucial involvement. The study showed that the environmental effects of a particular foodstuff can vary greatly depending on its origin and method of production. Consumers can therefore influence the environmental effects of food through their purchasing behaviour, provided they have the necessary information. The study also showed that meat and milk have a much greater environmental impact than plant-based products. In a further study, Agroscope showed for Swiss conditions that an optimised diet geared to the food pyramid is not only better for human health, but also protects the environment. For example, we can reduce the environmental impact of our diet by over 50 percent if we increase the proportion of cereals, potatoes, fruits and nuts on our plates; we should continue to drink milk and eat meat, but just a little less on average (Agrarforschung Schweiz, 2018).

‘We can reduce the environmental impact of our diet by over 50 percent if we eat healthily.’

How much do consumers know about the production of healthy food?

Unfortunately, it is a fact that large sections of the population today no longer have any direct contact with farming and that knowledge about food production is constantly declining. By means of this information campaign on plant protection, Agroscope is aiming to show the population, among other things, what it really takes and how many factors need to be in place in order to bring us our daily portions of healthy and attractive bread, fruit and vegetables. To do this, we depend on the support of many others: from primary school to technical college, from farming to research and from policy to administration.