224 NEW YORK STATE MUSEUM 



london purple and another the reverse. Yet both have been the object 

 of considerable experimentation and are of nearly equal value, though the 

 latter is said to be more variable in composition. The same may be said 

 of kerosene emulsion and a whale oil soap solution. In the case of these 

 preparations, it is always advantageous to make a few tests. To a certain 

 extent a man may depend upon the experience of others, but he should 

 also ascertain by trial what proportions, with his own apparatus and under 

 the conditions at hand, will give the best results. 



Arsenical compounds. These are effective against insects which 

 devour portions of a plant and of value only when placed where they will 

 be eaten. The following formulae are commonly employed : 



Paris green i pound 



Quicklime i pound 



Water 100-300 gallons 



London purple i pound 



Quicklime 2-3 pounds 



Water 100-300 gallons 



The more common proportion is at the rate of i pound of the poison 

 to 150 or 200 gallons of water, and less should be used on the more tender 

 foliage like that of the peach or there may be serious injury. The addi- 

 tion of hme is not necessary, specially with paris green, but is a wise 

 precaution as is neutralizes any free arsenic acid and thus prevents burn- 

 ing. Paris green can be applied with the bordeaux mixture,^ at the rate 

 of 4 ounces of the poison to 50 gallons of the fungicide, and in this 

 preparation both fungi and many insects find an effective check. 



If desired, paris green or london purple can be dusted on low plants, 

 such as potatoes and asparagus, when they are wet with dew, pro- 

 vided the poison is diluted with from 50 to 100 parts of flour or land 

 plaster. 



Another substance which has received high praise and may come into 

 general use after its good qualities become better known, is the arsenate 

 of lead. The value of this compound as an insecticide has been 



a The following formula is taken from Bulletin 114, Cornell university agricultural experi- 

 ment station : 



Normal or i.6% Bordeaux mixture : 



Copper sulfate, 6 pounds 



Quicklime, 4 pounds 



Water, 40-50 gallons. 



Dissolve the copper sulfate by putting it in a bag of coarse cloth and hanging in a vessel con- 

 taining at least 4 gallons of water, so that it will be just covered. Use an earthen or wooden 

 vessel. Slake the lime in an equal amount of water. Then mix the two and add enough water 

 to make 40 gallons. It is then ready for immediate use. If the mixture is to be used on peach 

 foliage it is advisable to add 2 pounds of lime to the above formula. 



