SUSCEPTIBILITY OF PYRUS GERMPLASM TO FABRAEA LEAF SPOT

A total of 218 genotypes of pear belonging to 10 pure and interspecific hybrid groups were rated for severity of infection with Fabraea maculata Atk. under epiphytotic conditions in the orchard for three years.
There were differences in the mean scores of 2-tree plots for some, but not all, genotypes.
The correlations of 1982 scores with 1983 and 1984 scores were not significant, and the correlation between 1983 and 1984 mean scores was of a low (r = 0.37), but significant magnitude.
Minimum scores and the mean of 1983 and 1984 scores are reported for 207 genotypes.
There was variability within the species and interspecific hybrid groups.
Interspecific hybrids with P. calleryana were rated as the most resistant, followed in order of decreasing mean score by complex hybrids of P. communis x (P. pyrifolia x P. ussuriensis), P. pyrifolia, P. pyrifolia x P. ussuriensis, P. communis, P. ussuriensis, P. communis x P. ussuriensis, and P. communis x P. pyrifolia. Seedlings progenies of P. calleryana and P. communis were rated for susceptibility during a 1976 epiphytotic.
The data suggest that the high level of resistance of P. calleryana is transmitted in an additive manner to its offspring.

Fruit Breeding

R.L. Bell, T. van der Zwet

https://doi.org/10.17660/ActaHortic.1988.224.28