PROGRESS IN BREEDING HARDY ROOTSTOCKS AND HARDY PEACHES 

 FOR THE FRESH MARKET AT HARROW 



R.E.C. Layne, Research Scientist (Pomology) 

 Research Station, Canada Agriculture, Harrow, Ontario 



The main objectives of the peach rootstock improvement pro- 

 gram at Harrow are to develop seedling rootstocks that have cold- 

 hardiness combined with good adaptation to light, sandy soils. 

 Other important attributes include: nematode and disease resis- 

 tance, size control, scion compatibility, seed productivity, ease 

 of germination, nursery uniformity and ease of budding. Appropri- 

 ate laboratory, greenhouse, nursery and field tests are conducted 

 to provide strong selection pressure for these characters. 



If some peach rootstocks were able to impart certain desir- 

 able characteristics to scion varieties, such as size control, pre- 

 cocity, or cold-hardiness, then the choice of rootstocks could be- 

 come almost as important as the choice of the scion varieties them- 

 selves. Most published evidence tends to discount this possibil- 

 ity. However, during the last four years, we have obtained a sig- 

 nificant body of data at Harrow which prove conclusively that at 

 least one peach seedling rootstock ' Siberian-C ' , in addition to 

 having very cold hardy roots, also imparts the following charac- 

 teristics to the scion variety: 1) greater cold hardiness, 2) ear- 

 lier defoliation, 3) earlier bearing, 4) greater production in the 

 early years, 5) earlier ripening, and 6) slight to moderate dwarf- 

 ing. These are important effects that have great commercial sig- 

 nificance. To date, no compatibility problems have been encoun- 

 tered with 'Siberian-C' 



This rootstock was released by the Harrow Research Station in 

 1967. The mother trees are virus free and the seed stocks are 

 virus free as well. Several seed orchards have been established 

 in Canada and the United States which should provide an adequate 

 seed supply to the peach industry in both countries in a few years. 

 It should be noted, however, that 'Siberian-C is not resistant to 

 root knot or root lesion nematodes. 



We also released another rootstock in 1967, 'Harrow Blood', 

 on account of its cold-hardiness and possible size controlling 

 ability. Further tests have shown that although 'Harrow Blood' 

 is more cold-hardy than 'Halford', 'Elberta' or 'Rutgers Red Leaf, 

 it is less cold-hardy than 'Siberian-C' Trees on 'Harrow Blood' 

 tend to be smaller than standard when young but the dwarfing re- 

 sponse tends to disappear as the trees attain bearing age. The 

 beneficial effects of 'Siberian-C on scion varieties previously 

 mentioned have not been noted with 'Harrow Blood.' It appears, 

 therefore, that 'Harrow Blood' should not be used if 'Siberian-C 

 is available. 'Harrow Blood' is also more difficult to handle in 

 the nursery than other commonly used peach seedling rootstocks. 



