12 



(2) Self-boiled Lime-sulfur. 

 This is used extensively on peaches and plums. The usual formula is 

 8-8-50, i.e., 8 pounds of quicklime, 8 pounds of sulfur, and 50 gallons of 

 water. 



(5) ''Sulfur Dust." 

 This product has scarcely progressed beyond the experimental stage. 

 It has been urged as a substitute for lime-sulfur and lead arsenate spray, 

 with the usual formula recommended of 90 parts of very fuiely ground 

 sulfur to 10 parts of the fluffy type powdered lead arsenate. 



3. Corrosive Sublimate. 

 This material finds its only use on the farm or in the orchard for the 

 disinfection of seed potatoes and of wounds on trees produced by pruning, 

 canker removal, etc. The tablets commonly purchased at drug stores 

 are of such a size that one tablet produces a 1-1,000 solution when dis- 

 solved in 1 pint of water. This is the standard strength at which this 

 product is used. The same dilution may be secured by dissolving 2 

 ounces of the salt in 15 gallons of water. 



4. Formalin. 

 Formalin is used for much the same purposes as corrosive subhmate, 

 although its use on potatoes is being discontinued in favor of corrosive 

 sublimate. According to the United States standard of purity for inter- 

 state commerce, 37 per cent of the weight of formalin must be formalde- 

 hyde gas, although the product is commonly spoken of as a 40 per cent 

 solution. It is used at a dilution of 1 part to 240 (1 pint to 30 gallons) 

 for disinfection of seed potatoes, and for disinfection of grain seed against 

 smut. For onion smut the formula of 1-128 has been extensively used. 



C. COMBINED INSECTICIDES AND FUNGICIDES. 



Most farm and orchard crops suffer from both insect pests and fungous 

 diseases. This necessitates the use of both an insecticide and a fungicide 

 on the same plant. Frequently, also, the presence at the same time of 

 more than one type of insect requires the application of both a stomach 

 poison and a contact insecticide. If the crucial time for application of 

 more than one should be approximately the same, it is usuali}^ possible 

 and profitable to combine them in a single application. Such a combina- 

 tion results in the saving of one-half to two-thirds of the time required for 

 separate applications, and, since labor is usually the big item of expense 

 in spraying, the cost is materially diminished. Unfortunately, however, 

 it is not possible to combine indiscriminately the various substances 

 which are used as fungicides and insecticides. Frequently, in combining 

 two or more of them, a reaction takes place which results in — 



