No. 6. DEPARTMENT OF AGRICULTURE. 393 



Dilution: (a) Process with specific gravity hydrometer. 

 Kule: Decimal of concentrate divided by decimal of desired spray 

 equals total dilution. 

 Examples: — 



.24 .24 .27 .27 



_= 8 or — = 24 or — = 38 4-7 or — = 90 

 .03 .01 .007 .003 



This means that a concentrate testing 1.24 is to diluted to 1 to 

 8 (total) to get a winter spray for scale, which should test 1.03, 

 etc. 



(b) Other methods: Dilution tables and floating hydrometer in 

 diluting vessel. Latter is unreliable as an indicator of proper water 

 addition, diffusion too slow. (For further discussion of these and 

 other matters pertaining to lime-sulphur, see our Bulletin 115.) 



DENSITIES AND APPLICATION TIMES FOR DIFFERENT PURPOSES 



San Jose scale, 1.03, trees dormant; or 1.01 in summer at *'hatch- 

 ing" time, followed by 1 or 2 later applications at ten-day intervals 

 or as young reappear. Other scales, same. 



Blister mite, 1.025, just as buds begin opening. 



Peach leaf curl, 1.02, just before the buds open. 



Apple and Pear scab and apple worm. About 1.007 with lead ar- 

 senate if three applications are given; 1.01 alone, or with the ar- 

 senate if only one application is given. Applications: (1) "V^Tien 

 blossoms are beginning to show pink; (2) May begin when petals 

 are two-thirds off and finish within ten days thereafter; (3) About 

 two weeks after second application. 



Brown Pot, Curculio and Scab of stone fruits. (1) Lead arsen- 

 ate, lime and water (2-2-50), when calyces or ''shucks" the shedding. 

 (2) Self -boiled lime-sulphur, 8-8-50. and 2 pounds lead arsenate, 

 about a month later. (3) Clear lime-sulphur solution. 1.003, or 

 self-boiled lime-sulphur, without any arsenical, about 3 or 4 weeks 

 before fruit ripens. The former alternative in (3) avoids staining 

 of fruit, is cheaper and handier and has been satisfactorily safe in 

 our tests the past two seasons. It should not be used extensively, 

 however, without preliminary trials in the locality and on the partic- 

 ular varieties to be sprayed. Peach spraying not yet as unqualified 

 a success as apple spraying. 



SPRAY INJURY 



Sometimes very important. When the sulphur solution is used 

 at proper densities, the injury may follow excessive applications 

 (see our Bui. 106), or be due to reactions between the lime-sulphur 

 solution and the arsenical, making the latter soluble. Lime sulphur 

 solutions containing any material quantities of soda or potash are 

 especially dangerous in the latter respect. (See our article on Peach 

 Spraying in 1911 Keport of State Hort. Assoc). 



We have wholly prevented the latter action on peaches during the 

 past summer, either by using lead ortho-arsenate, Pb3 (As04) 2, 

 with the lime-sulphur solutions, or by precipitating the sulphur from 

 solution with iron sulphate before adding the ordinary arsenicals. 



