Effects of environmental change: increased nematode pest status on UK crops.

Plant parasitic nematodes are important, economic, agricultural pests. They cause crop damage both directly as a result of their feeding and as viral vectors of diseases such as spraing on potatoes. Plant parasitic nematodes can be classified as either sedentary e.g. potato and beet cyst nematodes and root knot nematodes, or free-living e.g. stubby root and needle nematodes. Nematicides have historically been used to control nematode problems but have tended to be broad spectrum and relatively persistent. Legislation has already resulted in the recent loss of two major nematicides in response to the environmental concerns that their use raised. Amendments to relevant EU directives will cause loss from the market of the three remaining nematicides with limited prospects for safe alternatives becoming available. The loss of nematicide control and potential changes in climate present a dire situation for many British growers.
Climate change is predicted to increase summer temperatures in the UK by 2.4-4 oC and alter rainfall patterns with summers predicted to be drier by 30% (a median value from several climate models). Climate change could result in increased economic damage caused by nematodes that are already prevalent in the UK. Higher soil temperatures will increase the rate of development of plant parasitic nematodes resulting in greater multiplication of some and hence more damage to host crops. Earlier maturity of potato cyst nematodes may influence the proportion of the second generation that enters a period of dormancy, allowing greater re-infection of the crop within a growing season. The number of generations of beet cyst nematodes may also increase. The impact of cyst nematodes is enhanced when crops must also withstand the abiotic stress of dry soils as reported for potato, beet and other crops.
Climate change may cause nematode species that are prevalent, but infrequently damaging in the UK, to become important agronomic pests. Dry soils are detrimental to control of cereal cyst nematodes. They are normally under natural control from fungi but this suppression is reduced in dry summers because some of their fungal enemies infect nematodes with zoospores that require high soil moisture levels for their activity. This risks damage to the next cereal crop from an increase in overwintering population levels of cereal cyst nematodes. Changes in rainfall will also impact on those free-living nematodes that attack plants. For instance, high soil moisture enhances the activity of trichodorids and longidorids close to the soil surface leading to seedling damage as in Docking disorder of sugar beet.
Increased temperatures could lead to a greater threat from nematode species that are recorded rarely (but when found are present in high numbers) becoming widespread in the UK. There is a risk that alien species of root-knot nematodes, that are abundant elsewhere in Europe, can become established pests as UK soils warm.
In this work, nematologists will collect the biological information necessary for a climate impacts modeller to integrate the new information with that already available to predict increased risks from nematode pests of UK agriculture as climate change continues. Simulation models of UK nematode populations will be developed and tested using primary data relating soil temperature and moisture to nematode development, multiplication rates and crop damage. The model will be refined and tested using secondary biological data prior to being used with the UKCP09 climate data to project the risk of future nematode occurrence. Resolution will be to 25km2 and be related to soil type. The insights gained will be used to develop pest management strategies to mitigate the impact of changes in nematode pest status. This is necessary given chemical control of nematodes as used widely in the past is unlikely to be available to growers following changes in EU legislation.

Nematodes are economic, agricultural pests. They cause crop damage both directly and as viral vectors. Plant parasitic nematodes are classified as either sedentary e.g. Globodera, Heterodera species and the root knot nematodes, Meloidogyne species or migratory e.g. trichodorids. The species will be affected differently by climate change.
Several climate models predict increased temperatures in the UK by 2.4 - 4 oC and altered rainfall patterns with summers predicted to be drier by 30%. Climate change could result in increased economic damage caused by nematodes that are already prevalent in the UK eg. Globodera pallida and Heterodera schachtii. Climate change may also cause nematode species that are prevalent, but infrequently damaging in the UK, to become important agronomic pests e.g. H. avenae. H. avenae is normally under natural control from fungi but this suppression is reduced in dry summers. Changes in rainfall will also impact on those free-living nematodes that attack plants, e.g. trichodorids and longidorids. Increased temperatures could also lead to a greater threat in the UK from alien nematode species such as Meloidogyne species.
In this work, nematologists will collect the biological information necessary for a climate change modeller to integrate the new information with that already available to predict increased risks from nematode pests of UK agriculture as climate change continues. Simulation models of UK nematode populations will be developed and tested using primary data relating soil temperature and moisture to nematode development, multiplication rates and crop damage. The model will be refined and tested using secondary biological data prior to being used with the UKCP09 climate data to project the risk of future nematode occurrence. Resolution will be to 25km2 and be related to soil type. The insights gained will be used to develop pest management strategies to mitigate the impact of changes in nematode pest status.

The project will be relevant to, and have impact within, a number of key areas.
1. UK growers. The application is supported by the Potato Council, the Home Grown Cereals Authority and the British Beet Research Organisation (See letters of support). The programme also benefits from collaboration with ADAS. This indicates that the research has direct application to these strategic sectors.
Knowledge of the impact of climate change will be important for all aspects of the commercial agricultural sector - both for seed and ware crop producers. The Potato Council estimate the UK potato production, processing and retail market has an annual value of c. £3 billion. The research will, in the long term, support potato producers. The research looks at the impact of climate change on both sedentary and free living pathogens of this crop including those that act as viral vectors. Aspects of the project that focus on cereal and beet cyst nematodes support the other sectors of the agricultural community that could be heavily impacted by increased nematode problems as a result of climate change.
Nematode pests cause decline in agricultural output, for example the prevalence of G. pallida has contributed to a decline in the UK potato crop of 11.9% between 1999 and 2003. This is a larger fall than that of other major EU producers that lack this pest. This work will establish the likelihood of further impact of this and other emerging pests to the industry and thereby facilitate remedial actions.
2. Supermarkets. The major supermarkets value supply from UK growers. The outputs of the project will help plan and ensure that delivery of home grown produce is available to the consumer.
3. Policy-makers. DEFRA and The Scottish Government (RERAD) must implement the EU's amendment of Directive 91/414/EEC which seeks to reduce use of crop protection chemicals in EU agriculture. The Directive involves the abrupt or gradual withdrawal of pesticides from the UK market. DEFRA and RERAD must also support an EU Directive specifically aimed at potato cyst nematodes (2007/33/EC) that came into force in July 2010. The research will describe the potential increase in the economic impact of existing pests and the possible emergence of new nematode problems - as well as diseases caused by viral transmission by nematodes. This information will be central to policy makers to restrict the spread of new nematode threats and assess future pesticide needs.
4. General Public. The UK population consumes nationally grown crops. The crops are essential to maintain food prices. Import of many crops is simply not viable due to potential damage of the commodity in transit e.g. potatoes. The work will inform biotechnology and seed companies, growers and producers to ensure the economic delivery of our crops into the future, and thus ensure food security.
5: Environment. Highlighting the potential impact of nematodes as a result of climate change will ensure that a coordinated approach can be taken to the use of land for agriculture. Knowing the likely impact of pests in locations where crops could be grown will allow the optimal use of land and safeguard biodiversity.