verely you cannot cut away all blighted parts 

 without killing the trees. In these cases, it is 

 often effective to paint the cankered or dis- 

 eased areas with a formulation of zinc sulfate. 

 However, because this chemical can injure the 

 healthy tissues next to treated areas, you should 

 apply it carefully. 



To prevent secondary infection by other or- 

 ganisms in tree parts that you have pruned, 

 treat wounds and cuts larger than 1 inch in 

 diameter with a tree-wound dressing. 



After making each cut, dip the pruning tools 

 in diluted household bleach (sodium hypochlo- 

 rite). Mix 1 cup of 5.25-percent commercial 

 bleach with 9 cups of water. Because this solu- 

 tion will corrode metals, wash tools in water 

 each day at the end of pruning. Tools then 

 should be dried and oiled to prevent them from 

 rusting. 



Spraying and dusting 



The antibiotic, streptomycin, is one of the 

 most effective materials known for control of 

 fire blight. Begin antibiotic sprays as soon as 

 color is detected in the flower buds and every 

 3 to 5 days until the petals fall. Continue appli- 

 cations at 7- to 14-day intervals following the 

 bloom period. Stop spraying apples 50 days be- 

 fore harvest and pears 30 days before harvest. 

 Early evening and nighttime applications of 

 antibiotics provide better fire blight control 

 than daytime applications. 



Antibiotic sprays are partially absorbed by 

 plant foliage which may cause some yellow- 

 green mottling of the leaves (chlorosis). This 

 mottling disappears only after you stop using 

 the antibiotic. 



You can supplement pruning and the appli- 

 cation of zinc sulfate paints with a spray of 

 weak bordeaux mixture. This is prepared by 

 mixing 2 pounds of copper sulfate and 6 pounds 

 of hydrated lime in 100 gallons of water, or 

 two-thirds tablespoon of copper sulfate and 6 

 tablespoons of lime in 1 gallon of water. 



A commercial tribasic copper sulfate spray 

 mixture may also be used. Mix 1 pound of active 

 ingredients in 100 gallons of water, or 1 table- 

 spoon in 2 gallons of water. Also, a copper- 



lime dust mixture may be used; mix 20 parts 

 finely ground copper sulfate with 80 parts hy- 

 drated lime. 



Copper-base sprays or dusts applied to fruit 

 trees during or after spring blossoming may 

 cause the fruit to russet (develop rough, tough 

 skin). To minimize this when sprays are used, 

 apply sprays only when they will dry quickly. 



USE OF PESTICIDES 



Pesticides are safe and effective when used as directed. 

 Used improperly they can be injurious to man, animals, 

 and plants. The user is cautioned to read and follow all 

 directions and precautions on the label of the pesticide 

 formulation being used. 



The amount and frequency of pesticide use may vary in 

 different sections of the country. This publication is in- 

 tended for nationwide distribution. Users of this publica- 

 tion may also wish to consult their State Agricultural 

 Experiment Stations or County Extension Service for in- 

 formation applicable to their localities, or obtain the latest 

 recommendation if this publication is more than 2 years 

 old. 



The pesticides mentioned in this publication were Fed- 

 erally registered for the use indicated as of the issue of 

 this publication. 



PROTECT] 



fafatautisty^ 



Prepared by 



Plant Genetics and Germplasm 



Institute 



Northeastern Region 



Agricultural Research Service 



Washington, D.C. 



Revised February 1972 

 Slightly revised June 1976 



For sale by the Superintendent of Documents 



U.S. Government Printing Office, Washington, D.C. 20402 



Price 35 cents: $5 per 100 



Stock No. 001-000-03553-3 



■&U.S. GOVERNMENT PRINTING OFFICE : 1976— O-209-240 



