EVALUATION OF PYRUS GERMPLASM COLLECTED IN EASTERN EUROPE FOR FIRE BLIGHT RESISTANCE

During 1976–1980, three plant exploration trips were made by the senior author to five countries of Eastern Europe in search of Pyrus germplasm (Fig. 1). The principal objectives were to collect "native" pear germplasm with resistance to local insects and diseases and carrying pyriform fruit no smaller than 30 x 50 mm, to 1) widen the germplasm base in our USDA pear breeding program, and 2) provide information to the concerned countries in a reciprocal way for their horticulture programs.
A total of 389 accessions (235 from Yugoslavia, 87 from Romania, 43 from Poland, and 12 each from Hungary and Czechoslovakia) were collected as budwood and propagated at the U.S. Plant Introduction Station in Glenn Dale, Maryland.
Following 7 years of exposure to the fire blight bacterium (Erwinia amylovora), approximately one third of the accessions from each country appeared resistant (0–6% of tree blighted), whereas about two thirds blighted severely (50–100% of tree blighted). In addition, about 65 accessions, mainly from Yugoslavia, also have shown a high degree of freedom from leaf spot and insect pests, which confirms observations of the original trees at the time of collection.
Following virus indexing, multiple-resistant germplasm is being released and will be maintained at the National Clonal Germplasm Repository in Corvallis, Oregon, and be incorporated into the USDA pear breeding program in Kearneysville, West Virginia.

V International Symposium on Pear Growing

T. Zwet, R. Bell

https://doi.org/10.17660/ActaHortic.1989.256.21