30 



velops, the injured portions enlarge, resulting in russet blotches 

 and streaks. In wet seasons the russeting of the fruit is sometimes 

 so serious as to reduce its market value twenty-five per cent., or in 

 ::ome cases even fifty per- cent. 



The pathologists and apple growers have, therefore, been 

 driven to seek a less caustic fungicide and the result has been the 

 development of various lime-sulphur preparations. During the past 

 four years the Bureau of Plant Industry, and some of the Experi- 

 ment Stations, have been conducting experiments with lime-sul- 

 phur fungicides and the results have been such as to warrant the 

 recommendation of dilute lime-sulphur solution as a substitute for 

 Bordeaux mixture in a large part of the apple spraying operations. 



The Lime-Sulphur Sprays. 



For two or three decades a preparation known as the lime- 

 sulphur wash has been used in the dormant season for the control of 

 the San Jose scale and other scale insects. It has been known for 

 years that the same spray applied to peach trees in the early spring 

 two or three weeks before they bloom would prevent peach leaf- 

 curl and it is now a common practice to spray for scale and leaf- 

 curl at the same time using the lime-sulphur wash. The lime-sul- 

 phur solution, now rapidlv coming into use as a summer spray for 

 apples, is only a modification of the old lime-sulphur wash. 



Home-made Lime-Sulphur Solution. — Concentrated lime-sul- 

 phur solution to be diluted and used as a summer spray on ap- 

 ples may be prepared as follows: Boil i6 pounds of sulphur and 

 8 pounds of lime with lo gallons of water for about an hour, fin- 

 ishing with 8 gallons of concentrated solution. Then strain and 

 dilute it with water to make 200 gallons of spray. This makes 4 

 pounds of sulphur in each 50 gallons of spray, which, in our ex- 

 periments, has proved to be about the right strength for summer 

 spraying of apples. It may be made in larger quantities by using 

 100 pounds of sulphur and 50 pounds of lime and boiling them to- 

 gether with enough water to finish with 50 gallons of concentrated 

 solution. The boiling may be done in a kettle over a fire, or in a 

 barrel or other tank with steam. In diluting for summer spray- 

 ing 2 gallons of this solution should be used in 50 gallons of water. 

 Used at this strength in our experiments it controlled apple scab, 

 leaf-spot, and cedar rust, fuUv as well as Bordeaux mixture, with- 

 out seriously injuring the fruit or foliage.* 



Commercial Lime-Sulphur Solution. — A number of manu- 

 facturers are now placing on the market concentrated lime-sulphur 

 solutions to be used as a fungicide and an insectitude. Most of 

 these preparations test 32° to 33° on the Baume hydrometer and 

 contain in solution about 2^/2 to 234 pounds of sulphur to each gal- 

 lon. They are practically the same as the home-made solution, 



"-^For further information in regard to the preparation of concentrated 

 lime-sulphur solution see hulletin No. 99, Pennsylvania Agricultural Experi- 

 ment Station by Prof. John P. Stuart. 



