01997nas a2200157 4500008004100000245010700041210006900148260001200217300001400229490000800243520145800251100002001709700002101729700002301750856006601773 2013 eng d00aInoculum density relationships for infection of some eastern US forest species by Phytophthora ramorum0 aInoculum density relationships for infection of some eastern US  c09/2013 a595–6030 v1613 a
Our objectives were to establish inoculum density relationships between P. ramorum and selected hosts using detached leaf and whole-plant inoculations. Young plants and detached leaves of Quercus prinus (Chestnut oak), Q. rubra (Northern red oak), Acer rubrum (red maple), Kalmia latifolia (mountain laurel) and Rhododendron ‘Cunningham's White’ were dip-inoculated with varying numbers of P. ramorum sporangia, and the total number of diseased and healthy leaves recorded following incubation at 20°C and 100% relative humidity. Calibration threshold estimates for obtaining 50% infected leaves based on linear analysis ranged from 36 to 750 sporangia/ml for the five hosts. Half-life (LD50) estimates (the number of spores for which the per cent of diseased leaves reaches 50% of its total) from asymptotic regression analysis ranged from 94 to 319 sporangia/ml. Statistically significant differences (P = 0.0076) were observed among hosts in per cent infection in response to increased inoculum density. Inoculum threshold estimates based on studies with detached leaves were comparable to those obtained using whole plants. The results provide estimates of inoculum levels necessary to cause disease on these five P. ramorum hosts and will be useful in disease prediction and for development of pest risk assessments.
1 aTooley, Paul, W1 aBrowning, Marsha1 aLeighty, Robert, M uhttp://onlinelibrary.wiley.com/doi/10.1111/jph.12107/abstract