FORTIETH ANNUAL REPORT. 179 



be safely used with, it to effect a combination spray for both insects and 

 diseases. While on chemical grounds it appeared that the addition of 

 arsenate of le<id to tlie self-boiled lime-sulphur mixture would result in 

 an important decomposition of the spray and greatly add to its probable 

 injurious character, in practice the combined spray was found to be en- 

 tirely safe. Observations extending over three seasons have failed to 

 shoAV any serious injury resulting from the use of this spray, even when 

 as many as three applications were made. Thus, in the test of numer- 

 ous brands of arsenate of lead at Barnesville, Ga., during 1910, carried 

 out by Mr. E. W. Scott, of the Bureau of Entomology, peach trees were 

 given three thorough applications: (1) With arsenate of lead in lime- 

 water at tlie rate of 2 i)Ounds to 50 gallons, and (2) in the self-boiled 

 lime-sulphur wash used at the same strength. In all cases very serious in- 

 jury resulted to fruit and foliage on the plats sprayed with the arsenate 

 of lead in limewater, whereas there was no discernible injury on the plats 

 treated with arsenate of lead in the self-boiled lime-sulphur wash. It is 

 not understood why the arsenate of lead apparently loses its injurious 

 properties when used in the self-boiled lime-sulphur wash, though its 

 safe employment in this way is most fortunate. 



In the schedule of applications only two arsenate of lead treatments 

 are recommended, as these will measurably control the curculio and a 

 third treatment would considerably increase the danger of injury. 

 Where the curculio is very destructive, however, the grower should use 

 his judgment as to whether a third application of the poison would be 

 advantageous. 



The etfect of the arsenate of lead upon the fruit is to increase its color 

 notably. This increase in color from two applications in self boiled lime- 

 sulphur wash improves the appearance of the fruit. Three or even two 

 applications of the poison alone or in limewater, however, result in a 

 very excessive reddening, especially on the side exposed to the sun, on 

 which later may appear brown, sunken spots of variable size, accompanied 

 with more or less extensive cracking of the skin. This condition of the 

 fruit is shown ip figure 13. 



The self-boiled lime-sulphur mixture when properly prepared accord- 

 ing to directions does not injure the fruit or foliage, but if allowed to re- 

 main hot in concentrated form before dilution enough sulphur may go 

 into solution to produce injury to the foliage. Users of this spray should 

 therefore follow carefully the directions given for its preparation, bear- 

 ing in mind that a good mechanical mixture of the sulphur and lime 

 suspended in water and only slightly combined is desired rather than to 

 dissolve any considerable quantity of the sulphur. 



During the application of the spray, it is very important that the mix- 

 ture be kept well agitated to insure its uniform distribution. As both the 

 self-boiled lime-sulphur wash and the arsenate of lead quickly settle 

 when the spray is left undisturbed, an excessive amount may be applied 

 to some trees, while others receive an insufficient quantity. While most 

 spraying equipments are supplied with adequate agitating apparatus, the 

 orchardist should assure himself that the spray is being properly stirred 

 in the tank during its application. Under conditions of imperfect agita- 

 tion and consequent settling, the ingredients of tlie spray may be applied 

 so strong that serious injury will result. This has been observed to be 

 the case, especially following the employment of compressed-air sprayers 

 with inefficient agitators. 



