Challenge of hemlock (Tsuga spp) and true fir (Abies spp.) species with hemlock woolly adelgid (Adelges tsugae) and elongate hemlock scale (Fiorinia externa) [2007]
I conducted a study involving challenges of hemlocks and true fir seedlings with hemlock woolly adelgid (HWA) ovisacs and elongate hemlock scale (EHS) females. The seedlings were potted into containers and placed in a coldframe in University Park, PA. In May 2007 HWA inoculum was collected and applied to the seedlings. In June 2007 EHS inoculum was collected and applied to the seedlings. At the time of inoculation a 750 μm aperture mesh was placed over the plant.
Collecting EHS-infested branches for inoculum.
Hemlock seedlings inoculated with HWA and EHS.
All hemlocks and true firs had EHS infestation. Chinese hemlock had no HWA infestation. Resistance to HWA was not indicative of EHS resistance.
A true fir infested with EHS.
The results of this study were presented in a departmental seminar and at the 4th Hemlock Woolly Adelgid Symposium (Hartford, CT).
