CONTENTS. 



IX 



Bulletin 170 — continued. 



Tree surgery — concluded. 



Treating decayed cavities, filling, etc.. 

 Methods of treating cavities. 

 Shaping the cavitj', . 

 Concrete fillings, 

 Sectional concrete fillings. 

 Concrete coverings for the cavity opening. 

 Metal coverings, 

 Elastic cement. 

 Asphalt fillings. 

 Wooden block method, 

 Tree guards. 

 Fertilizing trees, 

 Diseases of trees. 

 Diagnosis of disease, 

 Fungous diseases of trees, 

 Wood-destroying fungi. 

 Slime-flux, . 



Treatment of fungous diseases of trees. 

 Winter injuries. 



Winter injuries of roots, 

 Winter injuries above ground, 

 Frost cracks. 



Winterkilling of cork cambium. 

 Sun scald, 

 Drought, 



Sun scorch and bronzing of leaves. 

 Mechanical injuries. 



Earth fillings around trees. 

 Bleeding of trees, . 

 Injurious chemical substances. 

 Kerosene oil, 

 Gas oil, 



Paint, .... 

 Miscible oils. 

 Road oil. 

 Creosote, 

 Coal tar, 



Salt, .... 

 Other injurious substances, 

 Banding substances, 

 Effects of illuminating gas on trees, 

 Effects of atmospheric gases on vegetation, 

 Electrical injuries. 



Effects of alternating currents. 

 General effects of direct currents. 

 Death of trees from direct current. 

 Electrolysis, 



Lightning, .... 

 Earth discharges. 

 Susceptibility of different trees to lightning stroke 

 Injuries to trees from arc lamps 

 Injury to trees from wires. 

 The spraying of shade trees, 



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