Host Defence and Genetical Resistance of Norway Spruce (Picea abies (L.) Karst.). Against Heterobasidion annosum (Fr.) Bref. : Root and Butt Rots

Uppsala

International Union of Forest Research Organizations, Swedish University of Agricultural Sciences

1994

S. 1-9

18 Lit. Ang.

Bandaufführung

91-576-4803-4

13462

73395

In spite of the high significance of the host defence and the genetical resistance of Norway spruce to pathogenic agents - especially to Heterobasidion annosum - these properties had been not examined for al long time. In the paper the results of our research work carried out during the last 30 years are described: 1. The roots of Norway spruce could generally not be infected by Heterobasidion annosum as long as they contained only living cells in their cross-section; 2. Young plants are able to repress the entered mycelium - i.e. they are in the position to heal up; 3. The older the host trees are the fewer and the less effective are the defence-reactions; 4. A proportion of older trees of different provenances or partpopulations, respectively, has coincident with a good growth potential also a high resistance: This proportion ranges between 5 and 20%, mostly about 10% of the trees; 5. The resistance seems to be conditioned additively by several minor genes - thus, it is a matter of a horizontal resistance; 6. By individual selection and vegetative propagation of trees with these desirable properties both the vitality and the stability of Norway sprucestands and consequently also the profitability of these stands could be considerably improved.