Widespread latent infection of Cryptostroma corticale in asymptomatic Acer pseudoplatanus as a risk for urban plantations
Abstract
Sooty bark disease (SBD) caused by the pathogen Cryptostroma corticale is currently one of the risks to the population of Acer pseudoplatanus in Europe. After a number of records of symptomatic and dead trees in Prague, assessment of the latent non-symptomatic stage of SBD was questioned as a means to forecast the health risk of the A. pseudoplatanus population.
We used two methods of early detection of C. corticale in non-symptomatic trees: cultivation from wood tissue on agar plates and a culture-free approach based on nested PCR with newly designed species-specific primers. The pathogen was detected in 25% of 112 examined trees from seven localities in Prague, but the disease incidence might be higher if more A. pseudoplatanus trees in Prague were included and if the crown infections were considered.
The presence of C. corticale was positively correlated with discoloured wood, but its presence did not depend on the occurrence of external symptoms. Infected trees were more frequently found in groups on steep sites at higher elevations.
In addition, heavier NOx pollution combined with more paths and roads increased the incidence of C. corticale.