90 



Kinds of Roots 



Date 



Tem- 

 pera- 

 ture 



Results 



Apple stock buried 5 

 in. below surface 

 outside since Jan. 

 8th 



Two year Ben Davis 

 apple roots 



Seedling peach roots... 

 Seedling peach roots... 



Elberta peach roots. . . 

 Elberta peach roots . . . 



Elberta peach roots. . . 



Seedling peach roots... 

 Seedling peach roots... 

 Marianna plum root... 



Marianna plum roots. 



Marianna plum roots. . 

 Marianna plum roots. . 



Kieff er pear roots 



Kieff er pear roots 



Kieffer pear roots 



Kieff er pear roots 



Mar. 8,'13 

 Mar. 24,'13 



June 25,'13 

 June 25/13 



Oct. 14/1 1 

 Oct. 18,'H 



Oct. 19,'ll 



Dec. 7/12 

 Dec. 7,'12 

 June 2S,'13 



June 26/13 



Dec. 7/12 

 Dec. 7/12 



Oct. 10/11 

 Oct. 14/11 



Oct. 19/11 



Mar. 27/13 



-14 

 -10 



-3 



-5 



-9.5 



-5.5 



-4.5 



-6.5 

 -4 



-5 



-4 

 -6.5 



-5.5 

 -9.5 



-4.5 



-10 



AH roots browned 



No injury in first 2 inches; cam- 

 bium injury throughout remain- 

 der. Cortex showed next greatest 

 injury, and in smaller roots sap 

 wood also injured. 



Entire system injured in cambium 

 and sap wood. Injury slightly less 

 in crown. 



All roots very severely injured in 

 cambium and cortex and portion of 

 sap wood. Crown as severely in- 

 jured as terminal roots. Stem just 

 above ground injured in cortex 

 and cambium. 



5 roots; 100% dead. 



13 inches of root length; 100% 

 dead. 



30J^ inches of root length; 100% 

 injured, smaller roots injured worst. 



Cortex, cambium and wood injured. 



Slight injury. 



Largest root injured severely in 

 cortex. No apparent difference 

 between crown and remainder of 

 root system. 



Crown 1 in. in diameter shows 

 slight injury in cambium; 3-10 

 in. down cortex injured also; sap 

 wood also injured towards tips. 



Slight injury in cortex. 



Cortex, cambium and sap wood in- 

 jured. 



H}4 inches; 65.5% dead. 



5 roots; 100% dead. Twigs at same 

 temperature, cambium only killed. 



33 Vz inches; 100% injured. Kill- 

 ing more severe in younger roots 

 some distance from the trunk 

 than in larger ones. 



Injury grading from none in crown 

 to injury of all tissues where di- 

 ameter of root was not greater 

 than 3-10 inch. 



It will be seen that the killing temperature of the roots varies 

 from about -3° C. in summer when most tender to about -12° C. in 

 late winter with rather rapid freezing. The roots are certainly as 

 hardy in March as in January. Thus they are later in becoming ;; jj 

 tender in spring than are twigs. They are still very tender in autumn 



