Articles
PEAR GERMPLASM OF THE NEW NATIONAL CLONAL REPOSITORY: IT’S EVALUATION AND USES
Studies and observations indicate that genes exist within the genus for resistance to: pear decline, fire blight, bacterial canker, Fabraea leaf spot, crown gall, Phytophthora root rot, pear psylla, pear leaf blister mite, wooly pear aphid, codling moth and root lesion nematodes.
Also found were genes for tolerance to lime-induced chlorosis, wet soils, dry soils, acid soils, cold winters and warm winters.
Other genetic traits in the collection regulate bloom date, bud-chilling requirement, leaf margin and shape, tree size (dwarfing), fruit skin color, fruit stone cells, deciduous calyx, carpel number, and fruit size.
Some work has been done on the relation of leaf polyphenols to pest resistance and to the taxonomy of the genus.
Rootstock efficiency and mineral nutrient uptake have been the subject of intensive study with this germplasm collection.
Beginning in 1912, F. C. Reimer, first superintendent of the Southern Oregon Experiment Station, began a search for resistance to fire blight in pear.
First he collected seed of the wild perry pears of France, along with the leading cultivars of Western Europe.
His search ultimately took him across the U.S. in 1915, where he found the blight resistant ‘Old Home’ and ‘Farmingdale’ clones grown by Benjamin Buckman of Farmingdale, Illinois.
Then in 1917 he travelled to China, Japan and Korea where he collected both wild and domestic pear species for testing.
These collections were retained by the Oregon Experiment Station, where they were evaluated for fruit quality or as potential rootstocks.
In 1960 following the entry into Oregon of pear decline, Henry Hartman, H. R. Cameron and I were assigned the task of coping with this new disease, caused by a mycoplasma which is transmitted to trees by pear psylla feeding on the leaves.
Between 1960 and 1970 we added to Reimer’s original collections by obtaining seed of primitive Pyrus from many countries including Japan, Korea, India, Pakistan, Russia, Iran, Iraq, Israel, Turkey, Lebanon, Greece, Yugoslavia, Hungary, Poland, France, Spain, Italy, Sardinia, Morocco, Libya and Algeria.
For collecting these seed we are indebted to J. R. Magness, H. J. Brooks, Q. B. Zielinski, C. G. Woodbridge, H. Olez, C. N. Ali, C. Fronistas, R. LePage, A. Ansoloni, E. Reffatti, E. Vestal, P. Spiegel-Roy, H. H. Tuck, T. van der Zwet, Y. Efraty, D. F. Millikan, W. L. Ackerman, B. Thibault, M. Iizuka,