Determination of tolerance to Erwinia amylovora of intergeneric hybrid genus: Cydomalus

A greater genetic diversity is essential for disease resistance in particular, and intergeneric hybridization makes this possible. The genus Cydomalus (syn: Cydolus), which is frequently used as rootstock, was derived from intergeneric hybridization between Cydonia oblonga Mill. and Malus domestica Borkh in Moldova and Bulgaria. It is known that hybrids from this genus exhibit quince and/or apple characteristics and some of them have been identified with reddish fruit skin color in Türkiye in the last decade. Erwinia amylovora Burril. is the most devastating bacterial disease in the Rosaceae family, and there have been no reports of Cydomalus. In this study, fire blight susceptibility index of three Cydomalus genotypes, were collected from İzmir and Manisa provinces, and two important quince rootstocks were determined by artificial inoculations with the most virulent Erwinia amylovora strain of our collection, under greenhouse conditions for two consecutive years. In addition, susceptibility levels of two Cydomalus genotypes were observed under natural disease pressure habitats. In line with the results of artificial inoculations, two of Cydomalus genotypes were determined to be more tolerant to fire blight disease than quince rootstocks and these genotypes could be used in breeding studies. Moreover, Cydomalus genus was identified as the new host for Erwinia amylovora.