Disease identified which could wipe out sweet chestnuts

Sweet chestnut blight disease has been confirmed in a tree in St Sampson’s.

Cankers spread throughout the tree surface, killing the tree. Young trees can succumb within a year, but it can take mature trees years to eventually die.

‘Sweet chestnut is not a widely grown tree in Guernsey, but it is an important part of our landscape,’ said Agriculture, Countryside and Land Management Services plant health inspector Nigel Clark.

‘By identifying any other infected sites, we will have a clearer picture as to whether eradication is possible or what control measures can be taken.’

There no obvious source for the St Sampson’s infection, so it is considered likely that this disease will be present elsewhere in Guernsey, and gardeners and landowners are being asked to check their sweet chestnut trees and report any symptoms.

The blight is a serious fungal disease. It enters through wounds or splits in the bark.

Typical symptoms include the cracking of bark and the presence of sunken cankers on the trunks of trees.

The disease may spread rapidly beneath the bark, resulting in wilting and the browning of leaves.

After moist weather, small orange fungal growths can be seen erupting through the bark.

Sticky spores can be spread by insects, birds and other small animals, or by the wind.

Infection can also spread on contaminated tools and equipment, and through the movement of infected logs.

There are no chemical pesticides available for the treatment of sweet chestnut blight. The only option available is the destruction of infected trees.

Guernsey has strict controls over the importation of sweet chestnut trees and logs to prevent the introduction of sweet chestnut blight.

Colin Dodd of Guernsey Trees for Life said that to help control these diseases, it was essential to keep monitoring and replacing local trees.

The infection has almost wiped out North America’s sweet chestnut population.

Although losses have not been on the same scale in Europe, sweet chestnut blight has spread steadily throughout much of Europe, and tree losses have been regionally significant.

The disease was first discovered in the UK in 2011, with two further outbreaks occurring in 2017, all affecting sites in southern England.

If any of the disease signs are spotted islanders are encouraged to take a picture and send it, along with site location, to the plant health inspector by email at agriculture@gov.gg or to leave a message on 01481 221161.