Selection of a genotype of Cotoneaster with a high level of resistance to fire blight.
Cotoneaster is, among the host plants of Erwinia amylovora, the genus which contains the highest number of susceptible and very susceptible genotypes to fire blight (circa 70%). Moreover, the number of very resistant cultivars, if any, is very limited. In this context, we attempted to create a new genotype. Seeds were collected from the less susceptible cultivars in our collection. Approximately 555 plants derived from 27 different cultivars were tested for three successive years (1996, 1997 and 1998) by inoculation of one strain of E. amylovora (CFBP 1430) under greenhouse conditions. As a result, only a few genotypes showed no symptoms. Of these, one genotype derived from C. dammeri 'Eichholz' was finally selected with this strain. This genotype was confirmed as fairly resistant under repeated inoculations with a number of strains of E. amylovora.