CONTENTS xi 



CHAPTER XV 



Page 



Winter Killing and Hardiness 250 



Death from Freezing — Tissue Freezing is Accompanied by Cell Dehydration; 

 Freezing, Not Cold, Ivills; Freezing and the Deciduous Habit — Increasing 

 Hardiness — By Increasing Sap Density — By Increasing Water-retaining 

 Capacity — Water-retaining Capacity Associated with Pentosan Content — 

 Water Soluble Pentosans in Particular — Pentosan Content, Water-retaining 

 Capacity and Hardiness Responsive to Environmental Conditions — In- 

 creased Hardiness with Increased Maturity — Rapid Temperature Changes 

 — Killing with Slow and with Rapid Freezing; Slow and Rapid Thawing — 

 Variation in Critical Temperatures — Summary. 



CHAPTER XVI 



Winter Injury 264 



Conditions Accompany Winter Injury; Winter Injuries Classified — Injuries 

 Associated with Immaturity — Affecting More or Less the Entire Plant — 

 Tender Plants May be More Resistant Than Hardier Plants; the Effect of 

 Summer Conditions Favorable for Late Growth; Second Growth Particularly 

 Susceptible; Preventive Measures — Localized Injuries — Crotch and Crown 

 Injury; Locahzed Injuries and Delayed Maturity; Contributing Factors; 

 Remedial Measures — Wiitter Injury Associated with Drought — Immaturity 

 and Winter Drought — Water Loss from Dormant Tissues — Water Conduc- 

 tion in Trees durmg the Winter — Relation of Freezing to Water Conduction 

 — Where Winter Drought Conditions Prevail — Protection against Winter 

 Drought Injuries — Winter Irrigation — Cultivation; Cover Crops — 

 Windbreaks — Effect of Wind Velocity; Effect on Evaporation; Effect on Soil 

 Moisture — Injuries Characteristic of Late Winter Conditions — The Rest 

 Period — Injuries to Fruit Buds — Changes in Water Content of Buds during 

 Winter^Contributing Factors — Protective Measures — Pruning; Fertiliza- 

 tion and Cultivation; Thinning; Whitewashing and Shading — In General — 

 Injuries to Vegetative Tissues — Distinguished from Summer Sunscald and 

 Injuries Associated with Immaturity; Moisture and Temperature Condi- 

 tions in the Affected Parts; Preventive Measures — Injuries Due to Sudden 

 Cold — General Effects; Trunk Splitting — Summary. 



CHAPTER XVII 



Winter Injury to the Roots 302 



Soil Temperatures in Winter; Critical Temperatures for Tree Roots — Factors 

 Influencing Frost Penetration — Protection Afforded by Snow; Different Sys- 

 tems of Soil Management; Soil Type; Soil Moisture — Relation of Cover 

 Crops to Root Killing — Root Killing in Different Fruits — The Apple; the 

 Pear; the Peach; the Cherry; the Plum; the Grape; the Small Fruits — Pre- 

 ventive and Remedial Treatments — Deep Planting and Mulching; Use of 

 Hardy Stocks; Pruning; Handling Nursery Stock .in Cold Weather — 

 Summary. 



CHAPTER XVIII 



Winter Injury IN Relation TO Specific Fruits 318 



The Apple — Injuries A.ssociated with Immaturity; Control Measures; 

 Varietal Differences — The Pear; the Peach; the Cherry; tTie Plum; the 



