Search Results (2)

To explore the possible relationship between diseased trees and wildfires, we assessed the flammability of canker-resistant and susceptible common cypress clones that were artificially infected with Seiridium cardinale compared to healthy trees. This study explored the effect of terpenoids produced by the host plant in response to infection and the presence of dead plant portions on flammability. Terpenoids were extracted and quantified in foliage and bark samples by gas chromatography–mass spectrometry (GC–MS). A Mass Loss Calorimeter was used to determine the main flammability descriptors. The concentration of terpenoids in bark and leaf samples and the flammability parameters were compared using a generalized linear mixed models (GLMM) model. A partial least square (PLS) model was generated to predict flammability based on the content of terpenoid, clone response to bark canker and the disease status of the plants. The total terpenoid content drastically increased in the bark of both cypress clones after infection, with a greater (7-fold) increase observed in the resistant clone. On the contrary, levels of terpenoids in leaves did not alter after infection. The GLMM model showed that after infection, plants of the susceptible clone appeared to be much more flammable in comparison to those of resistant clones, showing higher ignitability, combustibility, sustainability and consumability. This was mainly due to the presence of dried crown parts in the susceptible clone. The resistant clone showed a slightly higher ignitability after infection, while the other flammability parameters did not change. The PLS model (R²Y = 56%) supported these findings, indicating that dead crown parts and fuel moisture content accounted for most of the variation in flammability parameters and greatly prevailed on terpenoid accumulation after infection. The results of this study suggest that a disease can increase the flammability of trees. The deployment of canker-resistant cypress clones can reduce the flammability of cypress plantations in Mediterranean areas affected by bark canker. Epidemiological data of diseased tree distribution can be an important factor in the prediction of fire risk. Full article

Seiridium cardinale is a fungal pathogen responsible for pandemic cypress canker disease (CCD). The fungus has shown the ability to infect different hosts in many areas throughout the globe, but its spread and impact were favored by conducive environmental conditions. The most severe epidemics were reported in California and the Mediterranean, the former considered the source area of the pathogen from which the Mediterranean infestation have originated. Here we reconstruct the epidemiological history of the disease in California and the Mediterranean. Evolution of the disease in the two contrasting areas was weighed in relation to differences between the two environments in terms of climate, landscape properties, and adopted management practices. In addition, differences emerged among the source and invasive populations in terms of genetic and phenotypic variability, structure, and mode of reproduction allow a few comments to be made about the environmental implications and related quarantine of new introductory events. Full article