Ecology Distribution Management Info Impact Info References and Links Contacts

General Impact C. parasitica has had a negative cascading effect upon native forest composition and diversity throughout most of the United States since its introduction. Davelos and Jarosz (2004) state that, "American chestnut, C. dentata, was a dominant overstorey species in hardwood forests of the eastern United States of America prior to the introduction of blight (Day and Monk, 1974; Karban, 1978; Russell, 1987). In Southern Appalachian forests, the loss of mature chestnuts may have substantially reduced the forest's carrying capacity for certain wildlife species (Diamond et al., 2000). After the spread of C. parasitica, oak (Quercus spp.), red maple (Acer rubrum) and hickory (Carya spp.) became the dominant overstorey tree species (Keever, 1953; Stephenson, et al., 1991). Today, chestnuts continue to be an important understorey species because of sprouts produced by extant tree root systems (Keever, 1953; Russell, 1987; Stephenson et al., 1991). However, infected sprout clusters exhibit reductions in survival and size, particularly when in competition with other hardwoods (Griffin et al., 1991; Parker et al., 1993). Vandermast et al. (2002) state that, "Allelopathic qualities of chestnut leaves could have affected large areas of eastern forests. Chestnut foliage was dense, the leaf litter abundant and the leaves slow to decay ( Zon, 1904). Other studies indicate rain throughfall, dripping off live foliage, can contain concentrations of phytotoxic chemicals sufficient to inhibit germination of co-occurring species ( Al; Lodhi and Nilsen). With the abundance of competitive tree and shrub species in the southern Appalachians, it is possible allelopathy had an influence on maintaining chestnut's dominance in the region." In Italy, Dallavalle and Zambonelli (1999) state that, "There is a very high occurrence of chestnut blight on oak in the mixed woods of southern-central Italy where the pathogen still causes severe damage on chestnut ( Luisi et al., 1994). Although the occurrence of the disease on hosts other than chestnut does not involve damage to these trees it could play an important role in the epidemiology of the fungus."          Location Specific Impacts: Italy   Pathogenic: It is reported that there is a very high occurrence of chestnut blight on oak in the mixed woods of southern-central Italy where the pathogen still causes severe damage on chestnut ( Luisi et al.., 1994). United States (USA)   Economic/Livelihoods: The EPPO (2003) states that, "Between 1904 and 1950, Cryphonectria parasitica caused almost complete destruction of Castanea dentata in the eastern USA (Hepting, 1974)." Habitat alteration: Several insect species which are restricted to chestnut are now extinct or endangered (Schmitz and Simberloff, 1997) . Vandermast et al.. (2002) state that "Post-blight loss of allelopathic chestnut leaf litter could have contributed to changes in vegetative composition of eastern forests." Davelos and Jarosz (2004) state that, "The major epidemic following the introduction of C. parasitica into the United States has resulted in a rapid change in the species' place in eastern hardwood forests."