Field Susceptibility of Quince Hybrids to Fire Blight in Bulgaria

Authors: Postman, Joseph; BOBEV, SVETOSLAV - Agricultural University Of Bulgaria

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/10/2009
Publication Date: N/A
Citation: N/A

Interpretive Summary: Spread of the disease fire blight in Bulgaria during the last 20 years has nearly eliminated commercial production of pear and quince. Damage has increased in both nurseries and orchards, yet susceptible cultivars continue to be planted. Quince is the host most frequently attacked by the bacterial disease in Bulgaria. This pome fruit is widely cultivated in private yards and infected quince trees provide a source of inoculum that threatens pear and apple trees. Hundreds of quince selections were subjected to natural fire blight as part of a 10 year long breeding program. Fire blight epidemics in 2003 and 2005 provided an excellent opportunity to select the ones that were most resistance to fire blight. Trees were considered resistant if they had fewer than 15 blossom or shoot infections per tree, and less than 5% blighted canopy. Several new quince varieties have been selected that combine resistance to fire blight with high fruit quality. These selections will enable continued quince production while reducing disease incidence. Production of other pome fruit crops will also benefit from reduced inoculum levels.

Technical Abstract: Spread of fire blight in Bulgaria during the last 20 years has nearly eliminated commercial production of pear and quince. Damage has increased in both nurseries and orchards, yet susceptible cultivars continue to be planted. Quince is the host most frequently attacked by Erwinia amylovora in Bulgaria, where it is widely cultivated in private yards and infected trees provide a permanent source of inoculum. The importance of quince as a fire blight host encouraged a 10-year breeding program which subjected 274 hybrid progenies (3 replicates per selection on BA29) to natural fire blight infection. During the epidemic years 2003 and 2005, we identified 18 progenies that exhibited significant resistance to fire blight, with less than 15 blossom or shoot infection points per tree, and less than 5% blighted canopy. New quince genotypes have been selected that combine resistance to fire blight and high fruit quality. These selections will enable continued quince production while reducing disease incidence. Production of other pome fruit crops will also benefit from reduced inoculum levels.