42 INSECTICIDES AND SPRAYING 



foregoing. It rarely injures foliage and has the property of stick- 

 ing to leaf and fruit much longer than Paris green. It is always 

 used at a greater strength than Paris green is used, and with per- 

 fect safety. Its effect is not always so marked as the latter and in 

 at least one instance requires the addition of a little Paris green to 

 be really effective. The adult potato beetle is referred to, which 

 will hardly yield to arsenate of lead, although the latter is sufficient 

 to kill the larvse. Potato growers are advised to use two pounds 

 of arsenate of lead and one pound of Paris green in fifty gallons of 

 water. 



Arsenate of lead paste may be made at home, but with diffi- 

 culty, and the commercial article is preferable. Directions for use 

 of this and most other insecticides and fungicides are printed on the 

 can label. 



A powdered form of arsenate of lead may be purchased, which 

 can be mixed with water, but is perhaps not as satisfactory as the 

 paste. It is quite effective if it is mixed with air-slaked lime and 

 dusted on plants after a rain or when wet with dew. 



4. London purple is a by-product in the manufacture of aniline 

 dyes. It contains so large and such a varying percentage of soluble 

 arsenic that it is not a safe agent. It is little used at present, but 

 its cheapness is attractive. 



5. Combined Insecticide and Fungicide. Orchardists' needs 

 frequently require that fungous diseases and insect pests may be 

 treated in one spraying. Arsenate of lead may be safely and 

 effectively added to commercial lime-sulfur. Potato growers, 

 however, should combine Paris green with Bordeaux mixture. 

 The last-named fungicide is made by combining four pounds of 

 copper sulfate or blue vitrol, four pounds of quicklime, and fifty 

 gallons of water as follows: 



Making Bordeaux Mixture. The four pounds of copper sul- 

 fate are suspended in a cloth sack in twenty-five gallons of water in 

 some wooden receptacle. It will take several hours for this to 

 dissolve. In another wooden receptacle (a barrel, for example) 

 four pounds of quicklime are slaked in just enough water for this 

 purpose, and enough more water gradually added to make twenty- 

 five gallons. These two solutions may be then united or equal 

 portions taken from each container as desired. This compound, 

 like all other spraying mixtures, should be carefully strained before 

 beirig placed in the spray pump reservoir, barrel, or tank. Bor- 

 deaux mixture should be used as soon as made; it changes on stand- 



