New Crops p. 159 (1993)
Ed. Jules Janick, James E. Simon

Plant Exploration in Eastern Europe

Sour cherry exploration. The weaknesses of 'Montmorency', the 400-year-old French cultivar that comprises 99% of the United States sour cherry industry, and the extremely limited germplasm available in the United States made it imperative to acquire new germplasm in order to make any breeding progress. This moderate-sized tree species, Prunus cerasus L., which occurs wild and has been cultivated for a very long time in Eastern European countries, originated long ago from chance hybridization between the large-statured, cold-sensitive sweet cherry, Prunus avium L., whose native range includes Southeast Europe-Southwest Asia, and the shrubby, cold-hardy species, Prunus fruticosa Pall., whose distribution ranges farther north into the Soviet Union. The known sour cherry diversity found in regions surrounding the Caspian, Black, and Adriatic Seas suggests that this is the center of origin of this species. Since 1984, Amy Iezzoni has made five trips to seven Eastern European countries to study this variability and to collect germplasm (Iezzoni 1984). She found there a huge spectrum of variation ranging from plants that resemble the sweet cherry progenitor to those that are more similar to the other progenitor and all possible combinations of both. A wide variation was found in bloom time, fruit maturity, cold hardiness, important fruit qualities such as color, soluble solids, firmness, flavor, size, plant growth habit (from small dwarf trees to tall trees comparable to sweet cherry), and, of great significance, resistance to one of the most important diseases attacking our orchards, cherry leaf spot (Coccomyces hiemalis Higgins). She collected among the countless local cultivars that have been selected through centuries of cultivation, as well as acquired modern cultivars and selections from various Experiment Station breeding programs. Iezzoni's methods of approach have greatly hastened the exploitation of this new germplasm and serve as a fine example for what can be done to circumvent the lengthy quarantine period as well as the long generation time of fruit tree crops. In addition to introducing clonal material to the Quarantine system, she has made the best possible use of seeds and pollen and currently has over 10 ha of seedling trees representing new germplasm from elite sources. Not only has she collected and planted open-pollinated seeds from select cultivars in Eastern Europe; she has introduced pollen from abroad and used it for crosses with her local selections. In addition, because of the on-going working relationships she established, her European collaborators have made crosses for her between their selected clones and sent the hybrid seed for growing out in Michigan. Already these seedling trees are being screened for disease resistance, growth characteristics and fruit characteristics (Hillig and Iezzoni 1988; Krahl et al 1991). This rapid progress was made possible by an extremely important component of plant exploration, and one which is too often overlooked; that is, the establishment of friendships and on-going collaboration with individual scientists in the host countries which has the potential for long-term benefits for both parties.