How does elevated CO2 affect a foliar fungal disease of field-grown Acer rubrum?
Hoye, Katherine1, McElrone, Andrew1, Reid, Chantal1, Jackson, Robert 1, 1 Duke University, Durham, NC ABSTRACT- Little is known about the impact of disease on plants grown at projected elevated CO2 concentrations. To address these poorly understood interactions, we surveyed Acer rubrum trees for a leaf spot disease caused by the fungal pathogen, Phyllosticta minima, at the Duke FACE experiment, Durham, NC. Disease incidence and severity were lower under elevated CO2 with 21% fewer trees and 23% fewer leaves per tree exhibiting leaf spot, and reduced mean lesion area on infected leaves (5.12 and 6.35 mm2 for elevated and ambient CO2, respectively). Because the fungus enters the leaf through stomata, we investigated whether a decrease in leaf stomatal density and/or size with elevated CO2 could explain the reduced fungal infection. In the field, we tested this hypothesis by measuring leaf stomatal density and size of the stomatal aperture on leaf impressions of A.rubrum collected in the
