18 BULLETIN 120, U. S. DEPARTMENT OF AGRICULTURE. 



it can undoubtedly be modified when necessary to meet the local re- 

 quirements of other districts in which the disease may demand treat- 

 ment. No recommendations regarding the use of insecticides are 

 given, but it will be understood that the arsenicals and nicotine solu- 

 tions which can safely be employed should be added in the proper 

 amounts required for insect control at the various times when the mil- 

 dew applications are made. This statement applies equally well to 

 other districts than the Pajaro Valley. Several years of experi- 

 mental and commercial spraying have demonstrated that the various 

 arsenicals commonly employed, and also nicotine solutions, can be 

 combined with the iron-sulphid mixture without affecting the insecti- 

 cidal or fungicidal value of any of the materials. 



FIRST APPLICATION. 



The first application should be made at the time of and in conjunc- 

 tion with the first spraying for the control of the codling moth, and 

 the combined spray, containing iron-sulphid mixture and the neces- 

 sary insecticides, should be prepared as directed under " General for- 

 mula for the spray mixture," on page 17. 



The object in making this first application of the iron-sulphid 

 mixture so early in the season is to develop sulphur immunity, which 

 will lessen the danger of fruit and foliage dropping that might result 

 from the subsequent sprayings, and to keep the early foliage pro- 

 tected from the mildew. 



SECOND APPLICATION. 



The second application should be made in conjunction with the 

 second spraying for the control of the codling moth, and the kinds 

 and amounts of insecticides regularly employed in this second cod- 

 ling-moth spraying should be added, as directed under " General 

 formula for the spray mixture," on page 17. 



In some apple-growing districts it may be found that on account 

 of the rapid growth of the early foliage large numbers of mildew 

 infections will become established on the leaves during the interval 

 between the first and second sprayings. In that case it will un- 

 doubtedly be advisable to make an application of iron-sulphid mix- 

 ture, 20 gallons of the stock mixture diluted to 200 gallons of spray, 

 about 10 days after the petals fall. The sulphur stimulation of 

 foliage growth resulting from these early sprayings is a very im- 

 portant factor in insuring vigorous foliage conditions later in the 

 season. The writers have had opportunity to observe the decided 

 improvement in foliage vigor on blocks that received these early 

 treatments as compared with other portions of the same orchard that 

 were not given the first spraying with iron-sulphid mixture until 

 relatively late in the spring. 



