FA4 Pesticide use

>> Background information

Development

The use of pesticides increased significantly until the late 1970s and remained at a high level throughout the 1980s. This was followed by a steep decrease in the early 1990s, but after 1996 the use of pesticides has begun to increase again. The use of both herbicides and fungicides has increased.

The pesticide risk index takes into account not the only the total volume of pestice sales, but also the sales of different active ingredients as well as the environmental impacts of these. It considers factors such as toxicity and rate of accumulation into animals as well as the ingredient's stability in soil. According to the risk indicator more harmful fungicides were sold in 2006 than previously. The increasing use of proportionally more harmful fungicides has been a clear trend since the mid 1990s.

As the use of herbicides remained at a high level during 1960?1980, the diversity and abundance of weeds decreased significantly. The steep decrease in the use of herbicides by the mid 1990s and possibly also changes in cultivation methods led to a new increase in weed numbers. Especially perennial monocotyledonous weeds such as quackgrass became more abundant. The increase in the sales of herbicides since 1996 may thus be seen as a reaction to crop losses caused by these weeds. The recent increase in herbicide sales is mainly due to the increased use of glyfosate, a new chemical introduced to fight quackgrass.

The commercial production of biological plant protection organism started in the 1990s. Their sales have since grown rapidly. In 2010 61 tonnes of biological pestices were sold in total.

Impact on biodiversity

Herbicides and insecticides directly decrease the diversity and abundance of plants and insects of farmland habitats. All wild plant species growing on cultivated fields may be considered weeds. By competing with cultivated species weeds decrease their yield. The impact on yield varies according to the line of production. Normally the decrease ranges from 5% in spring cereal fields to up to 50% in sugar beet fields. Insecticides also affect species which are not considered pests.

By destroying weeds and the invertebrates living on them herbicides also have an impact on vertebrate species. The reproductive success of, for example, the Grey partridge has been shown to be affected by the decrease of insect food that follows from the use of pesticides. Young partridges feed on the invertebrates they find on weeds during the first couple of weeks of their lives. If the supply of protein-rich food is not sufficient, the growth of the birds slows down and they become more susceptible to disease and predators. At its strongest the use of pesticides has an impact on the viability of adult vertebrates. The most toxic compounds weaken the animals and affect their reproductive success.

In recent years one of the main active ingredients used in herbicides has been Glyfosate. In the light of present knowledge it is not very harmful to animals and does not leach from fields in any considerable amounts. Glyfosate is strongly absorbed into the soil where microbes break it down completely. Even when released in water glyfosate does not accumulate in organisms.

As a result of the agri-environmental support scheme pesticide treatment of field margins and buffer strips has mainly become prohibited. The use of pesticides is also prohibited on organically cultivated fields. Altogether the use of pesticides is forbidden or restricted on approximately 150 000 hectares, out of which organically cultivated fields cover more than 90 percent.

Biological control has become more common during the last few years. Biological control substances are produced from natural organisms and then distributed in large quantities on fields. Their effectiveness is based on competitive advantage, sometimes also the formation of toxins. Biological control substances are very selective and effective only against specific pests. In addition, there are only few of them on the market for the present which is why biological control substances can not yet substitute all chemical pesticides.