Resistance of the roots of some fruit species to low temperature ..
ONTENTS PAGE Review of the literature 613 Method used in freezing the roots 616 Results of the experiments 618 Resistance of apple roots to low temperature 618 Resistance of pear roots to low temperature 624 Resistance of Elberta peach roots to low temperature 627 Comparative resistance of Mazzard and Mahaleb cherry roots to low temperature 629 Resistance of Myrobalan plum roots to low temperature 632 Resistance of the roots of six grape varieties to low temperature . . 633 Resistance of
... esistance of blackberry, dewberry, and red raspberry roots to low temperature 637 Resistance of gooseberry and currant roots to low temperature . 6Si Sap concentration of American and French apple seedlings and Wilder currant as measured by the freezing-point depression 642 Effect of rapid temperature fall on the freezing of apple roots 64c Effect of rate of thawing on the freezing of roots 64Î njury to apple roots when frozen in soil, in water, and in paraffin. . . 64( Influence of the scion on the hardiness of one-year roots of the stock. 646 Effect of sugar solutions, water, and drying out, on the resistance of apple roots to freezing 653 Summary 656 literature cited 660 609 There are several types of winter injury to fruit plants which are of more or less frequent occurrence in New York State. Among these may be mentioned injury to small twigs, especially those of peach trees and of tender apple varieties such as Tompkins King; injury to the winter buds and sometimes to the blossoms; sun-scald, and the rather closely related forms of crotch injury and crown rot; and injury to the roots. Perhaps the killing of the roots by low temperature should be associated with the less serious types of winter injury in this State, due in part to the fact that it occurs in restricted areas. Yet in the Champlain Valley and in the upper Hudson River section, the freezing of the roots is one of the important problems in fruit production. This is also the case in parts of New England, in Canada, and in a number of the Western States. The work reported in this paper was begun in the fall of 1915 andê xtended thru the spring of 1917. An attempt has been made to determine approximately under standard conditions the range of variation and the relative hardiness of some of the more commonly grown fruit stocks, including a few varieties of the small fruits. Some data were also obtained regarding the influence of certain factors on the freezing to death of plant tissue. Careful field studies and the testing of possible fruit stocks capable of withstanding severe cold are significant aspects of the question that have not been attacked. It is hoped, however, that some of the results presented here may be suggestive in the working out of these other phases of the problem of root injury by low temperature.