NOTES ON FRUIT BREEDING FOR THE NORTHWEST. 343 



Siberia, the home of the true Siberian cralj which the Russians have 

 found essential to use for stocks to prevent root-kilUng at the north. 

 The Russians themselves long- ago found out that even the hardiest 

 apples would not be hardy at the north when used as stocks and. 

 hence, took the Siberian cral) as a foundation for their northern or- 

 chards. 



Captain Reed : Do you know of any standard apple from which 

 we can raise seedlings as hardy as those from the Siberian crab 

 seed ? 



Prof. Hansen : The winter of 1898-9 proved to me that no 

 standard apple seedling (Pynis mains) will endure 40° below zero 

 with no snow on the ground. At this same time the seedlings of 

 the pure Siberian crab proved perfectly hardy. 



^Ir. Fay : Will you recommend the planting of a hybrid apple 

 such as the Briar Sweet, which, as you know, is Siberian in its 

 parentage ? 



Prof. Hansen : We are getting on the danger line there at least 

 for the far north. From this latitude south I presume there would 

 be no essential difference. 



Air. Underwood: What do you mean by hardiness? 



Prof. Hansen : Resistance to cold is what we usually refer to at 

 the north. The other use of the term, meaning resistance to heat, 

 we are not especially concerned about, except that northern trees in 

 general do not do well far south. 



Mr. Underwood : In what way does cold afifect a tree ? 



Prof. Hansen : Sudden alternate freezing and thawing kills 

 the live cells in the cambium layer, as is noticed in sunscald of apple 

 trees. There is a certain degree of cold that will kill an oleander 

 and the same temperature will not aft'ect an apple tree. A fuchsia 

 is killed by cold that will not harm a peony. This resistance to cold 

 is something inherent in the constitution of the plant itself. I quit 

 coddling my plants long ago. After the first year they must take 

 their chances unprotected froiji the cold. If not they must make 

 way for plants that will. 



Mr. Nordine : Some believe that the evaporation of moisture in 

 the limbs changes the texture of the tree. Has that anything to do 

 with the hardiness of the tree itself? . 



Prof. Hansen : It is certainly true that shoots that are too wa- 

 tery and full of sap in the fall will not endure the winter as well 

 as when fully ripened. Other things being ecjual, an apple tree that 

 ripens its wood well in the fall stands a better chance of enduring 

 cold unharmed than one that keeps on growing and does not ripen 

 its wood properly. But just what hardiness is in a plant is indeed 

 difficult to determine from a study of the cell structure. Alature 

 wood and thick, firm leaves, I think, help, but nothing very definite 

 has been brought out in that line. Hardiness is something inherent 

 in the live tissues of the plant bred into the tree during thousands of 

 years of "the survival of the fittest."" A point I wish to make is 

 that we should take this inherent cold resistance that has been de- 

 veloped by the action of this law and in time breed from it plants 

 native to a milder climate. 



