Abstract

The Environmental Objectives Council has given the government agencies responsible for the environmental objectives an opportunity to review what significance a changed climate may have for the prospects of attaining the 16 environmental quality objectives. The Swedish Parliament (Riksdag) has decided on the 16 environmental quality objectives which are to be attained by 2020. The Swedish Chemicals Agency, which is responsible for the environmental quality objective A Non-Toxic Environment, has chosen to commission a report on what challenges a changed climate may pose for the need for plant protection in agriculture, which is of great significance to A Non-Toxic Environment. Agriculture as well as society at large make great use of, and are heavily dependent on, a large number of chemical products with an impact on the environment and health, and the environmental quality objective A Non-Toxic Environment is consequently regarded as one of the most difficult environmental objectives to achieve. An important interim target is to reduce the risks in the use of chemical plant protection products, and climate change may further reduce the prospects of attaining this target. The report summarises existing knowledge on the effects of climate change on the need to use chemical plant protection products and also what methods exist and what changes are required to counteract increased use. This work comprises the following parts: · Summary of climate scenarios for Sweden · Summary of effects of a changed climate on pests and weeds · Estimation of change in the use of chemical plant protection products in a new climate up to 2085 according to various future scenarios · Description of how cultivation systems and cultivation measures that fulfil requirements for a non-toxic environment might look in a changed climate · Discussion on the need for action and research The methodology used in the project is literature studies, compilation of statistics and interviews and discussions with researchers and other experts. A reference group of representatives of the Swedish Chemicals Agency, the Swedish Board of Agriculture, the Swedish Environmental Protection Agency and the Federation of Swedish Farmers has been involved in the work. According to the regional climate scenarios of the Swedish Meteorological and Hydrological Institute (SMHI), average temperature in Sweden may rise by more than the global average temperature during the current century, and this may mean that the temperature in southern Sweden will be equivalent to present-day conditions in central to northern France, and that the northern part of Götaland (the southernmost part of Sweden) will have temperatures similar to the northern parts of Germany. The number of days in the summer with extremely high temperatures, above 30 °C, may increase in particular in southern Sweden. It is anticipated that total precipitation and also patterns of precipitation will change. Winter precipitation is expected to increase sharply by 2050, with the highest precipitation levels continuing to be in the south-west and the mountain chain. Precipitation patterns in the summer are expected to change in a non-linear manner, principally in Götaland, with wetter weather in the middle of the century, while drier summers are expected around 2085 in parts of the area, 11 for example in the important production area of the southern plains of Götaland. July and August in particular are expected to become drier than today. The drier summer climate in the south is thus expected not to occur until the end of the century, while higher mid temperatures occur earlier. To summarise, it is anticipated that problems relating both to weeds and to disease and insect attack will increase in a changed climate. It is anticipated that the number of species that may become problematic weeds will increase, and that the geographic range of weeds will move north. Winter annual grass weeds already pose problems today in autumn-sown crops, particularly in the major crop winter wheat, and these problems are likely to increase. In drilled crops that do not compete strongly, such as sugar beet, maize and field vegetables, the presence of both established and new weed species may increase sharply. Major attacks of fungal diseases are predicted chiefly in winter wheat, for example attacks of rust fungi that greatly reduce yields. Moisture-loving fungi, such as common anthracnose, on the other hand, may decrease in dry areas. Blight attack in potatoes will probably increase, particularly in northern Sweden where the level of attack at present is low. In many cases projections for attack by fungal diseases are highly uncertain due to the fact that climate change works in different directions. Higher temperatures combined with increased precipitation generally favour fungal attack, while drier summers may lead to lower pressure of infection by fungi. Aphid attacks are expected to become more serious, partly due to the increased risk of attack in winter cereals during the autumn, which only occurs to a small extent at present. Other insects that may increase in cereals are cereal leaf beetle and thrips. Increased presence of virus-carrying insects such as a number of aphid species poses an increased risk of the spread of viruses in several crops. New pests may also become problematic, such as Colorado beetle in potatoes. The use of plant protection products can be described by various indicators or combinations of these, such as 1) total quantity of active substance used, 2) proportion of treated acreage, 3) frequency of treatment and 4) dose used in relation to full dose. Use is described in the report through the indicator proportion treated acreage in per cent x frequency of treatment. Indicators of present-day use have been taken as a basis and an assessment has then been made of conceivable future use in a changed climate. Various sources have been used in the calculation of indicators, such as statistics on the use of plant protection products in Sweden and other European countries, scientific literature on effects of climate on weeds and pests, and interviews with researchers at the Swedish University of Agricultural Sciences (SLU) and experts at the Plant Protection Centres of the Swedish Board of Agriculture. Indicators of use in a changed climate are largely based on subjective assessments and are subject to great uncertainty. The absolute values of the indicators should therefore not be over-interpreted, but they do indicate a trend. No account has been taken of the significance of possible increased use of non-chemical methods, or of other factors that may have a great impact on use, such as economic and political factors. Present-day production systems are adapted to plant protection based on chemical plant protection products. Extensive changes of cultivation systems, crop distribution, crop succession, cultivation measures and plant protection methods are required for reduced use to be possible. As it is anticipated that plant protection problems will increase in a changed climate, there will be an even greater need for new plant protection strategies in the future if it is to be possible to keep the risks in the use of plant protection products at a low level. 12 It has emerged in the work on this report that there is a need to improve statistical data on the use of plant protection products in order to be able to follow trends in Sweden and to make comparisons with other countries possible. Detailed statistics are desirable on the number of treatments in different crops in different production areas combined with the proportion of treated acreage, as these are important measures of the intensity of use. Detailed statistics are also useful as a basis in order to be able to take the right measures for reduced risks. Statistics on quantities used in different crops are too imprecise a measure to be used in tracking trends in use. The use of plant protection products today is dominated by herbicides, followed by fungicides and then insecticides. A shift towards greater use of insecticides in particular is anticipated in a changed climate. According to the indicators used in the report, use of insecticides is expected to increase by 54 per cent in an unchanged distribution of crops, fungicides by 42 per cent and herbicides by 22 per cent. There are wide differences between crops in indicators of the use of plant protection products, particularly with regard to fungicides and insecticides. This is clearly illustrated in the scenarios with differing distribution of crops presented in the report. Changes in the distribution of crops in a new climate may have just as great an impact on the use of plant protection products as the direct effects of climate. Increased cultivation of winter wheat substantially increases the combined indicators for the whole acreage, particularly in a changed climate. The use of plant protection products is already high in winter wheat, and the indicators for fungicides and insecticides in particular are expected to increase sharply in the future scenarios. An increase in the acreage of crops with a low need for control, particularly of forage crops on which almost no pesticides are used, obviously has a great impact on the indicators of use. Increased cultivation of forage crops on intensively farmed plains is particularly decisive in allowing the risks of plant protection products to be reduced. This is made clear in a southern Swedish forage crop scenario in the report, where the proportion of forage crops was increased from 14 to 21 per cent of the total acreage in the area. The indicators were reduced by 27 (fungicides) and 22 per cent (insecticides) in a changed climate in the forage crop scenario compared with an unchanged crop distribution, Increased organic production obviously contributes to fulfilment of the objective of A Non- Toxic Environment. However, to increase the effect on the environmental objective the organic cultivation of pesticide-intensive crops needs to increase, for example winter wheat and potatoes. How great the change in the use of plant protection products will be depends greatly on adaptation measures in agriculture, in the shape of a change in production systems and crop distribution and utilisation of preventive measures and non-chemical methods of control. Regulations and economic instruments and changes in the profitability of agriculture will also have a great impact on use. Research initiatives are needed, such as fundamental biological-ecological research, applicable non-chemical methods and in particular overarching interdisciplinary research to formulate long-term sustainable plant protection strategies in a whole crop succession. Research on effective non-chemical methods of control of weeds, such as mechanical methods, are regarded as particularly important as there is extensive use of herbicides in most crops. The indicators for herbicides are also expected to be higher than for fungicides and insecticides in a changed climate. A special area highlighted in the report is methods against grass weeds in crop successions dominated by autumn-sown cereals. In addition, it is judged 13 that research on biological control of pests by favouring natural enemies, and non-chemical methods in drilled crops, for example horticultural plants, should be prioritised. High-quality plant protection advice is essential in order to raise the level of knowledge among Swedish farmers on effective alternative methods and integrated plant protection in order to limit weeds and pests and reduce the use of chemical plant protection products. Another important basis for advice is economic and environmental impact assessments of plant protection strategies in different crop successions. Environmental payments are a significant instrument to stimulate the application of integrated plant protection and alternative non-chemical methods of control. It is important, in designing economic instruments, to take account of the fact that several environmental objectives may be affected by proposed measures, for example A Non-Toxic Environment and Zero Eutrophication, and to address any conflicts of aims between different types of environmental effects. There is a need for knowledge and methods in order to be able to weigh up different environmental objectives to make work on the objectives more effective

Published in

Publisher: Kemikalieinspektionen

SLU Authors

• Wivstad, Maria

  • Department of Crop Production Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use
Agricultural Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/34340