01645nas a2200157 4500008004100000245012200041210006900163260001600232300001400248490000800262520111000270100002001380700002101400700002301421856004301444 2014 eng d00aEffects of Inoculum Density and Wounding on Stem Infection of Three Eastern US Forest Species by Phytophthora ramorum0 aEffects of Inoculum Density and Wounding on Stem Infection of Th cJan-03-2014 a683 - 6890 v1623 a

Seedlings of three Eastern US forest species Quercus rubra (northern red oak), Quercus prinus (chestnut oak) and Acer rubrum (red maple) were inoculated by applying Phytophthora ramorum sporangia to stems at different inoculum densities with and without wounding. Disease occurred in all treatments involving wounds, and no disease was observed in unwounded treatments. Younger seedlings (2–3 years old) did not differ significantly from older seedlings (5–6 years old) in disease incidence, but older seedlings sustained smaller lesions compared with younger seedlings. For both old and young seedlings, disease on wounded stems was observed down to the lowest sporangia concentration utilized (500 sporangia/ml for old seedlings and 100 sporangia/ml for young seedlings). The results show that in the presence of wounding, even very low sporangia concentrations can result in disease, and further suggest that wounding caused by insects and other factors may play an important role in P. ramorum epidemiology in forest environments.

1 aTooley, Paul, W1 aBrowning, Marsha1 aLeighty, Robert, M uhttp://doi.wiley.com/10.1111/jph.12251