Written by Colleen O’Sullivan, Tree Officer, London Borough of Camden and first published in the Arb magazine Winter 2017

The London Tree Officers Association recently visited the city of Turin, Italy on the 12-13 October for a fantastic, jam-packed two day tour of the city. The visit was held in collaboration with the Turin Municipality through their Forestry Manager Gianmichele Cirulli.

The purpose of the trip was to further learn about the processes and systems in place in Turin to cope with Cerastocyctis platani, or canker stain of plane (CSP). This follows a visit to London by Gianmichele in December 2015, where he presented at an LTOA seminar about CSP. Nine members of the LTOA were able to attend, a mix of London tree officers, a Municipal Tree Officers Association tree officer and associate members.

Day 1 started at the Turin City Hall, where the group met other council officials in a beautiful 17th century meeting room including the assistant deputy Mayor, Simone Manchilli who explained how they are trying to improve the perspective of Turin residents to trees, promoting their ecosystem services and human health benefits. They have also been working with the cities of Oakland and Portland USA. Becky Porter gave a short presentation on the LTOA’s role in supporting tree officers and work members have completed recently.

City Hall meeting room

The group next visited the Environment Park, where they met with several individuals working for the regional government of the Piedmont. Sergio Cravero who is the head researcher for CSP in the region explained the history of Plane Wilt in the area (present since 1979) and the measures which were in place to control the spread of the disease. The regional government works closely with the city of Turin to help track the movement of the fungus as well as ensure control measures are in place. Their research showed the spread of CSP was due to infections on the trunk, primarily through mechanical damage at the base of the trees.

The LTOA delegation was taken to the plant pathology lab at the Environment Park to see how CSP is identified. Petrie dishes were passed around, with Silvio Grosso explaining how the fungus compared to other fungi normally found in Plane wood samples. A fruiting specimen was under a microscope for further inspection by the group.

Fruiting bodies of Cerastotcyctis under the microscope

The afternoon was spent at the Turin Polytechnic Department of Architecture and Design where a seminar was held on urban tree management. Three presentations were given by LTOA members Becky Porter, Al Smith of LB Camden and Jeremy Barrell of Barrell Tree Consultancy. Two presentations on pests and diseases of Northern Italy were given by Dr Chiara Ferracini and Dr Paolo Gonthier both of University of Turin. Many of the pests diseases found in Italy are also found in Britain. This was followed by a great traditional Italian meal out with Gianmichele and Daniele with many local dishes served to the group’s delight!

Day 2 started with the felling of two large London planes, one of which was found positive in September for the “red cancer” as CSP was called by Gianmichele and his colleagues. The neighbouring tree is felled as a precautionary measure to stop the spread of the fungus. To limit the amount of saw dust produced and reduce the spread of Plane wilt, the infected trees are removed with as few cuts as possible. This is facilitated by a crane and rigging equipment. Typically the infected trees are removed in two cuts. Joining in on the demonstration of the crane removal of the trees were a couple of private companies including Arboteam. They also demonstrated the use of new rigging equipment, which made the work faster and safer.

LTOA members anticipating the fell

The area where the felling was taking place is the oldest infected area of Turin. Planes are a vital part of the Turin landscape and the municipality have been planting the CSP resistant species PLATANOR® Vallis clausa. Adjacent to the tree being felled was a 10 year old avenue of PLATANOR® Vallis clausa along the river Po. They have found the tree to be quite water demanding, but overall the clonal species is doing well. It should be noted that they are resistant, not immune, so they can’t be imported to the UK because there is a chance that they will be infected with CSP. Experts elsewhere in Italy are sceptical of this species so time will tell how well they get on in Turin.

Gianmichele explaining all the permits needed for removal of a plane with the “red cancer”

Craning of the still healthy tree over the infected tree

Moving from the point of removal to the point of replacement side of things the group was taken to the Municipal nursery to see the existing plant stock held by the municipality. The Turin nursery is the last remaining municipal nursery in Italy with no current plans to get rid of it as they see it as a major asset for the city. The plant stock are typically bought from commercial nurseries as standard trees, planted in the ground for a couple of years, then potted up awaiting planting in the streets. This is done to acclimate the southern Italy grown trees to the different climate that Northern Italy has. The nursery currently held about 700 trees and several thousand small shrubs. Stephana Cirulli spoke about the challenges of buying in trees with uncertainty of whether they would be planted up in future due to financial constraints and a smaller work force available.

Avenue of Plane Wilt resistant Planes

Turin’s municipal nursery

The day finished with a food truck providing lunch and drinks for all attendants of the day. Though the trip was only two days, it was filled with very valuable insight into how Turin manages their trees and pests and diseases, especially CSP. With the knowledge gained, the members of the LTOA will be better prepared to take on CSP if it hits these shores. We would like to thank Becky Porter for arranging the study tour on our side and Gianmichele Cirulli and all his work colleagues for providing us with a fantastic two days of knowledge sharing and enjoyable conversation. We look forward to future collaborations!

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