Abstract
The aim of this project is to: Define strategies to exploit risk assessment, genetic resistance and natural defences against crop pathogens, to avoid waste of resources, crop spoilage and dependence on fungicides. Reducing the environmental footprint of farming will require more efficient use of natural assets. Disease and its management affects the use of resources – energy, water and disease resistance genes – that have wide implications from their use. These resources are used predominantly to establish, grow and maintain green canopy. In return, interception of light energy and carbon capture by green tissues creates dry matter from photosynthesis with an energy value as food or fuel. Diseases affect the green canopy, wasting resources and causing spoilage. Considering the effect of disease on the efficiency of use of each resource: Water: Approximately half of the rainfall onto arable land is transpired by crop canopies before it can reach ground water or water courses. Foliar diseases have long been known to reduce water use efficiency; work in the 1930s showed that oat crown rust infection increased the water used per gram of crop dry matter produced from 270 grams to 530 grams. Until recently water was not perceived as a limited resource, so such findings were treated largely as academic curiosities. Recent work has shown that certain important types of disease resistance to pathogen infection impact on water use by disrupting stomatal function. There is a need to devise methods to minimise water wastage due to pathogens and resistance mechanisms. Energy: The balance between energy inputs to crops and the resulting energy outputs is becoming more important as concern about green house gas (GHG) emissions increases. The energy cost of producing fertiliser nitrogen (N) accounts for approximately half of the total energy input into arable crop production. Pathogens acquire their N from the crop, but the area of canopy affected by disease symptoms, and hence the waste of N, far exceeds uptake by the fungus. The energy output of the crop is affected by the resulting loss of interception of solar energy. Strategies for disease management should optimise crop energy ratio. Resistance genes: Control of disease is maintained primarily by two highly dynamic interactions: firstly between the introduction of new host resistance genes and pathogen populations overcoming them by becoming virulent (in recent decades, major yellow rust resistance genes have only remained effective for about two years from introduction); secondly between the introduction of new fungicide modes of action and pathogen populations becoming insensitive to them. Apart from concerns about the long-term sustainability of using genetic and chemical resources in this way, the rates of introduction and loss of efficacy have become rather tenuously balanced in recent years. The waste caused by disease and dependence on fungicides can both be reduced by exploiting resistance genes and other natural defences, such as the ability of plants to tolerate disease. These defences must be deployed efficiently, as they form part of the natural asset base. Previous attempts to devise strategies for the deployment of disease management resources have been based on the natural sciences and have not taken sufficient account of the effects of economic and social drivers. The work proposed here would interact with research council initiatives creating links between the natural and social/economic sciences, and with the plant breeding industry, to identify practical strategies. The project will consist of work packages, each addressing the effect of pathogens and disease management on the efficiency of use of a particular resource. The packages will be linked by a common quantitative framework (developed in WP1) to analyse the relative effect of different strategy options to improve resource use efficiency. Work package 1 (ADAS) will develop a quantitative framework to compare disease risk management strategy options (developed in the other work packages) for their effects on waste, resource use efficiency, dependence on fungicides and economics. Work package 2 (Rothamsted) will quantify the net benefit of different deployment strategies of genes conferring resistance to plant diseases. Work package 3 (Nottingham) will identify strategies to minimise the impact of disease and disease resistance on water use efficiency. Work package 4 (ADAS) will devise strategies utilising sustainable disease resistance and natural defences to minimise the cost of diseases to energy and carbon efficiency, and GHG emissions. Work package 5 (Rothamsted) will develop a methodology to build warning update systems that complement models providing early season risk assessments for foliar pathogen epidemics. Work package 6 (ADAS) will facilitate communications with stakeholders, disseminate new findings and advocate sustainable disease risk management strategies which avoid waste of resources. This project will support the Defra aim of reducing the environmental footprint of farming, and provide evidence and advice to support policy decisions. The resulting specific benefits to consumers and the environment will be through producing fuel and wholesome food with less dependence on fungicides, whilst increasing water use efficiency, minimising GHG emissions and reducing loss of efficacy of resistance genes.
United Kingdom