ISHS Acta Horticulturae 69: II International Symposium on Pear Growing
POSSIBILITY OF COMBINING LOW LEVELS OF FIRE BLIGHT RESISTANCE IN PEAR |
| Author: | T. van der Zwet |
| Abstract:
Low levels of fire blight resistance within P. communis can be successfully combined and increased to a height not observed previously in this species. Combinations of 'Bartlett', 'Seckel', 'Comice', and 'Ree Carlo di Wurtemberg' ('RCW') each provided some degree of resistance which were additive, resulting in resistant selections such as Mich.-US 437, US 301, US 307, US 309, US 342, US 539, and others. The combination of additive sources of resistance have resulted in highly resistant cultivars such as Magness, Moonglow, and Dawn. Resistance to fire blight can be destroyed, however, by combining resistant selections with cultivars such as 'Conference', which contribute susceptibility to progeny. Evidence has been obtained for a dominant gene, Se, in these cultivars, causing unusual sensitivity to the blight organism. Approximately half of the variability in resistance to blight in pear is additive. The high frequency of highly resistant selections resulting from crosses between nonsensitive (sese) P. communis cultivars indicates that selection for high resistance within progenies of such populations will result in a genetic gain. | |
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