In March of 2008 we published an article entitled ” Timing of pruning Plane trees questioned”
In that article we said sometimes the only thing one can do is cross your fingers and hope.
Only four days previous to those words we wrote an article about the plight of the plane trees in this area which are gradually succumbing to an encroaching fungus. (article here) – the canker stain fungus
In that article we wrote that just a very small wound is enough to allow the fungus to invade the plant tissue and start the infective process.
The parasite can be invade the tree at various levels including on the main or secondary branches subject to frequent pruning.
We also wrote that it was probably only a question of time before the fungus makes its way up the mountainside to Barga.
That morning in March 2008, the plane trees on the Fosso just outside the main walls of Barga were pruned by workers for the Provincia of Lucca.
As bad luck would have it the wind that morning was coming from the South so there was possibly a very dangerous situation as the fungus can travel by air from the infected sawdust emanating from the chopped down trees further downwind in the valley and infect the newly pruned plane trees in Barga.
We finished the article with the words ” Let’s hope that the pruning of these trees just at this time has not put them at added risk from this deadly silent menace that is decimating the plane tree population in Tuscany.”
Four years later in November 2011, those trees started to be cut down, as you can hear in the short interview below
The cause of canker stain of plane trees is the fungus Ceratocystis fimbriata Ell. et Halsted, f.sp. platani Walter (=Cfp) (Ascomycotina, Ophiostomatales)
So how does the fungus do its dirty work ? Even a very small wound is enough to allow the mycelium to invade the plant tissue and start the infective process.The parasite can invade the tree at various levels: on the main or secondary branches subject to frequent pruning; on the trunk, always exposed to wounds from various causes, especially near ground-level; and on roots that emerge above-ground, as occurs with trees growing in compacted and anaerobic soils that are frequently encountered in street and city plantings.
In the 1940’s canker stain ravaged urban plantings of plane trees in the larger American cities along the Atlantic coast. During the second World War wood from infected trees was used to package materials for the war effort, and this is probably how the pathogen was introduced to the European continent, giving rise to the processes of infection here.
This supposition is borne out by the fact that the first centres of infection in Europe were in or near the major port cities: Naples, Livorno, Syracuse, Marseilles and Barcelona, which were very active during and after the second World War. It is likely that at first only one of these ports became ‘infected’ with the parasite from overseas, and that from this single point it spread out to other Mediterranean port cities.
The first epicentre of the disease in Italy is thought to have been the Naples-Caserta area (Cristinzio et al., 1973); this hypothesis is confirmed by the fact that, when the disease was detected for the first time at Forte dei Marmi in Tuscany, it had already killed many of the 200 year-old planes lining the Vialone Carlo III, the broad avenue that leads to the Palace of Caserta.
Canker stain did not assume an epidemic pattern until several years later, but then it spread in a dramatic manner through Italian cities, as it had done in North America before. A survey from Forte dei Marmi revealed that in the 20 year period 1972-1991, 90% of all planes there became infected and died. Subsequently the disease spread out from Forte dei Marmi to much of Versilia and to many towns of Tuscany: Massa Carrara, Lucca, Pisa, Livorno and Florence. – source; Journal of Plant Pathology (1999)
Judging by some of the ominous spray painted plane trees once more visible on the Fosso in Barga Vecchia, it would seem that crossing our fingers and hoping just is not enough to stop the fungus which has already killed most of the plane trees in Forte dei Marmi before moving onto and decimating many of the famous trees on the walls of Lucca during the 80’s and early 90’s before gradually gradually moving up the valley.
Ceratocystis fimbriata è l’agente della malattia denominata “cancro colorato”, che provoca la morte dei platani. E’ un parassita fungino da ferita, la cui pericolosità è correlata non solo alla sua aggressività, alle sue diversificate capacità di diffusione e alla suscettibilità della specie, ma anche, e soprattutto, alle notevoli difficoltà nel controllo, specialmente in ambito urbano.
l vettore principale della malattia è costituito dalla non corretta esecuzione delle operazioni di potatura. Nei confronti di questo patogeno è in vigore un decreto di lotta obbligatoria, che prescrive controlli ed interventi da attuare per la salvaguardia del patrimonio vegetale.
Le piante colpite da Ceratocystis fimbriata devono essere prontamente abbattute per legge. In Toscana lo dispone l’ARPAT.
Non esiste alcuna cura a quanto pare, ma l’eliminazione degli alberi infetti è comunque un´arma a doppio taglio: se da un lato si cerca di eliminare la sorgente di inoculo, dall´altro le operazioni di abbattimento producono enormi quantità di segatura e di frammenti di legno infetti, che sono una delle principali fonti di diffusione della malattia.
I platani devono essere abbattuti con tutte le precauzioni possibili, raccogliendo la segatura prodotta e distruggendola insieme al restante materiale infetto.