Infection of Norway spruce container seedlings by Gremmeniella abietina

Berlin

2008

S. 1–15

11 Abb., 3 Tab., 25 Lit. Ang.

200145012

First- and second-year containerized Norway spruce seedlings were inoculated with conidia of type A (large tree type) and type B (small tree type) of Gremmeniella abietina var. abietina at different times during the summer. The appearance of symptoms after artificial inoculation and natural infection on spruce seedlings were recorded the following spring and compared with the disease symptoms on Scots pine seedlings. The proportion of diseased seedlings after inoculation reached as high as 80%. The susceptible period during the summer began later on the first-year seedlings than on the second-year seedlings, and was similar for the pine seedlings. Susceptibility of first-year seedlings was highest in August and on second-year seedlings in July. The accumulated temperature sum, relative humidity and height growth for first- and second-year seedlings was assessed. Natural infection in 2002 caused more disease on pine than on spruce seedlings. Experimental thinning of seedlings had no effect on disease incidence.