Ceratocystis platani is an ascomycete fungus that causes canker stain of plane tree, a serious disease of Platanus spp. in the United States and Europe. The fungus is a wound parasite, and can colonise even small wounds upon contact. After wound colonisation mycelium develops throughout the conducting tissues of the underlying sapwood. Colonisation can be 2.0-2.5 m/year from a single infection (Soulioti et al., 2008). \r\n

The disease causes staining of the xylem, disruption of water movement, cankers and usually death of the tree. The most obvious disease symptom on oriental plane is sudden death of a portion of the crown. Cankers on the tree trunk, although not always visible through thick, rough bark, are characterised by necrosis of inner bark and bluish-black to reddish-brown discolouration of sapwood (Ocasio-Morales et al., 2007). Trees of 30-40 cm diameter may die within 2-3 years of infection (Soulioti et al., 2008).

Ceratocystis platani attacks trees in the genus Platanus, including American sycamore (P. occidentalis), oriental plane (P. orientalis), London plane (P. acerifolia; a natural hybrid of P. occidentalis and P. orientalis) and California sycamore (P. racemosa). Oriental plane is considered highly susceptible to the fungus; American sycamore is relatively resistant and London plane is generally intermediate in resistance (18, 28 in Ocasio-Morales et al., 2003).\r\n

C. platani can survive for several years at -17°C but will not grow below 10°C or above 45°C. The fungus can survive for >105 days in soil during winter, but is killed by temperatures of 35-40°C (Accordi, 1989 in Soulioti et al., 2008).

Most Ceratocystis spp. have a sexual state but, like many Ceratocystis spp., C. platani can self via unidirectional mating type switching. Selfing is likely more common than outcrossing in such Ceratocystis spp. (Ocasio-Morales et al., 2007 and references therein).

Ceratocystis platani attacks plane trees in the genus Platanus causing canker stain. This is a serious disease of plane trees in the United States and Europe, causing staining of the xylem, disruption of water movement, formation of cankers and eventually death (Ocasio-Morales et al., 2007). Trees infested with the fungus usually die within 3-7 years (Fredon Corse, 2011).\r\n

The pathogen is having a dramatic impact on the natural populations of oriental plane (Platanus orientalis) in southwestern Greece. Hundreds of dead and dying trees have been found along streams and rivers, with patches of 15-20 often evident (Ocasio-Morales et al., 2007). Such significant losses of plane trees is expected to have a dramatic impact on riparian forests of the region. Streams have been found to have stretches of up to 100 m with no surviving plane trees. As the pathogen spreads forest composition may change dramatically because P. orientalis is highly susceptible to canker stain (Ocasio-Morales et al., 2007). In Greece many ornamental trees have died in residential and recreational areas too; some of which were large and centuries old, and thus have historical importance (Ocasio-Morales et al., 2007).

In 2006 C. platani was identified as the cause of dying plane trees in France’s UNESCO world heritage site, the Canal du Midi. The canal is lined with around 42,000 plane trees which are under threat from the fungus. To date around 2,500 trees have been felled and destroyed. The trees have huge historical, aesthetic and personal value to many who live in the area, and the loss of trees could threaten the UNESCO World Heritage status (Willsher, 2011).

According the INRA and various agencies there is currently no effective chemical or biological control against this fungus, as the mycelium penetrates deep into the wood and is not affected by current products (Fredon Corse, 2011). Thus control of this disease should focus on preventative measures. Such measures include avoiding injury to Platanus trees, disinfecting tools before and after working on trees, burning of any diseased tree tissue, removing any sawdust from areas, treating any wounds and injuries with antifungal washes and avoiding planting susceptible trees in contaminated areas (Fredon Corse, 2011). Such methods may make it to contain infestations or slow down its spread; particularly in areas where the disease is limited in extent, such as Greece where it is currently localised to the Messinia Prefecture. Such containment methods should be imposed before it spreads throughout the natural range of ecologically and historically important Platanus orientalis (Ocasio-Morales et al., 2007).\r\n

In the Canal du Midi, France large numbers of diseased plane trees have been removed and planted with resistant varieties (Willsher, 2011).