About sweet chestnut
Sweet chestnut (Castanea sativa) is generally classified as a non-indigenous but ‘honorary native’ species in Britain and Ireland. Native to southern Europe and Turkey, it has long been cultivated for its timber and its edible, starchy nuts. The species is predominantly found in the southern half of Britain and is well adapted to a wide range of site and soil conditions normally occupied by mixed broadleaved communities of oak, hazel, birch and ash. Due to its relatively recent arrival in the UK, few species are directly dependent on sweet chestnut as a host, but it does support a wide range of invertebrates, fungi and lichen that are associated with equivalent broadleaved trees.
Sweet chestnut is predicted to thrive in Britain & Ireland under future climate change scenarios but is threatened by two diseases. ‘Ink disease’ is caused by a range of soil borne fungi (Phytophthora spp.) and leads to crown reduction, early leaf fall, stem necrosis and tree death. Although widespread, ink disease does not typically cause significant tree losses unless the ground is poorly drained and compacted. Chestnut blight, caused by the fungus Cryphonectria parasitica, has caused significant regional losses in Europe since the 1930’s and was first identified in the UK in 2011. As of 2020, there have been several occurrences in southern England and regulations are in place to minimise the spread of this disease. There is evidence that the disease can be weakened by a natural virus that infects and attenuates the fungal pathogen. The phenomenon is known as hypovirulence and is already being used as a form of biological control in many European countries to minimise the impact of chestnut blight.