Paper Reviewed
Oliveira da Silva, C.E. and Ghini, R. 2014. Plant growth and leaf-spot severity on eucalypt at different CO2 concentrations in the air. Pesquisa Agropecuária Brasileira 49: 232-235.

Introducing their study, Oliveira da Silva and Ghini (2014) write that "species of Cylindrocladium have been described as important fungal pathogens of various Eucalyptus and Pinus, causing considerable loss in tropical and subtropical regions, commonly associated with nursery diseases such as root rot, damping-off and leaf-spot," citing Alfenas et al. (2004). Against this backdrop, the two Brazilian scientists grew Eucalyptus urophylla seedlings for 30 days in plastic boxes with clear-glass lids at 451, 645, 904 and 1147 µatm CO2, after which they inoculated them with the pathogen Cylindrocladium candelabrum and kept them under the same environmental conditions for seven more days, after which they assessed the growth of the seedlings and the degree of disease incidence and severity.

Did elevated CO2 provide any relief from the pathogen?

In going from the lowest to the highest atmospheric CO2 concentrations, shoot dry weight increased by 47% and root dry weight by 24%, while leaf-spot disease incidence declined by 36% and its severity by 57%.

Clearly, the results obtained by Oliveira da Silva and Ghini are very gratifying. And the fact that they say "these favorable effects of rising atmospheric CO2 concentration on the severity of C. candelabrum leaf-spot and eucalypt growth agree with the results obtained by Santos et al. (2013) and Ghini et al. (2014) for Ceratocystis wilt and rust, respectively," makes them even more gratifying.

References
Alfenas, A.C., Zauza, E.A.V., Mafia, R.G. and Assis, T.F. 2004. Clonagem e Doeneas de Eucalipto, Universidad Federal de Viçosa: Viçosa, Brazil.

Ghini, R., Mac Leod, R.E. de O, Torre Neto, A., Cardoso, D.C., Bettiol, W., Morais, L.A.S., Vique, B. 2014. Increased atmospheric carbon dioxide concentration: effects on eucalypt rust (Puccinia psidii), C:N ratio and essential oils in eucalypt clonal plantlets. Forest Pathology: 10.1111/efp.12117.

Santos, M. de S. dos, Ghini, R., Fernandes, B.V. and Silva, C.A. 2013. Increased carbon dioxide concentration in the air reduces the severity of Ceratocystis wilt in Eucalyptus clonal plantlets. Australasian Plant Pathology 42: 595-599.