Stability of Resistance to Seiridium cardinale Canker in Some Clones of Common Cypress : Shoot and Foliage Diseases in Forest Trees. Proceedings of a Joint Meeting of the Working Parties Canker and Shoot Blight of Conifers (S2.06.02) Foliage Diseases (S2.06.04)

Florenz

1995

S. 118-125

17 Lit. Ang.

Bandaufführung

13577

77401

Resistance to Seiridium cardinale bark canker in cypress takes the form of a post-infection compartmentalisation producing the scarring over of the cankered area. This defence reaction has been the subject of research in a number of cypress clones for some years, primarily in order to identify resistant clones suitable for ornamental plantings, and to obtain improved (resistant) seed for reforestation. More recent studies have however revealed that canker resistance is in part dependent upon environmental factors, in particular weather and soil conditions. This has made it necessary to test for clonal variations in canker resistance with in different environments. Fifty clones in two sites in central Italy were inoculated and the resultant level of infection was evaluated statistically with analysis of variance, which detected a significant genotype x environment interaction. The data from the clones at the two sites were compared and a parametric approach was used to show: 1. within-clone variation, using the general and local coefficients of variability for each clone, and 2. variability of individual clones with respect to the test sample as a whole, using Wricke's ecovalence. In this way the clones effectively causing the interaction with the environment could be identified. The character bark canker resistance did not seem sufficiently stable in the tested clones to hold out the prospect of universally resistant clones; different clones should be looked for, each of which is canker resistant in a particular environment.