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Circular No. 656 



August 1942 • Washington, D. C. 



UNITED STATES DEPARTMENT OF AGRIC 



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Wound Dressings on Apple Trees 



By J. S. Cooley, 1 senior pathologist, Division of Fruit and Vegetable Crops and 

 Diseases, Bureau of Plant Industry 



CONTENTS 



Introduction- 



Review of literature 



Development and preliminary evaluation of 



wound dressings 



Experimental tests of dressings „. 



Materials and methods 



Relation of time of wounding and treat- 

 ment to healing _ 



Page 



1 

 2 



3 



5 



Experimental tests of dressings— Continued. Page 

 Reaction of wounds to different treat- 

 ments 12 



Woolly apple aphid deterrents and aphicides 



in relation to perennial canker 15 



Conclusions and practical considerations 16 



Summary 17 



Literature cited 18 



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INTRODUCTION 



The treatment of pruning wounds of fruit and other trees has 

 been of interest to orchardists and other plantsmen for many years, 

 and as a result many different types of wound dressings have been 

 devised. In an endeavor to prevent certain diseases of which the 

 causal organisms enter through wounds, such as those of the canker 

 type, plant pathologists have prepared and studied wound dressings 

 and have recommended various treatments. Most of these have, 

 however, had some decided shortcomings. 



A study of wound dressings for woody plants and of their effects 

 on wound-inhabiting parasites and on the hosts involves many phases 

 of the physiology of the wounded and treated plants. The wide- 

 spread use of wound disinfectants in animal surgery has possibly had 

 its influence on the use of wound dressings on plants. However, the 

 wound reactions of plants and animals differ in many respects, and 

 erroneous conclusions may follow from presumed analogies. 



One of the most important aspects of the pruning-wound problem 

 is the fact that until completely callused over, a wound remains 

 unprotected from checking and weather influences and is susceptible 

 to attack by fungi that cause wood rots. Rapid healing of pruning 

 wounds and the lasting qualities of any dressing used are therefore 

 important. The readiness with which a wound heals is correlated 

 with such factors as the general vigor of the tree, the amount of 

 leaf surface above the wound, the nature of the wound dressing 

 applied, and the time of the year when the wound is made. 



1 Grateful acknowledgement is here given to Jesse H. Crenshaw, formerly agent in this Division, for help 

 on the part of the work carried on at Hood River, Oreg. 



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