25 



exposed in the air ; thus it can be used on plants bearing- fruit which is 

 just about ready for market, with much more safety than can be the min- 

 eral poisons. This volatility of the alkaloid also shows the necessity of 

 using a fresh article and one that has been kept away from the air in a 

 tightly sealed receptacle. 



Use either the dry powder or with water, i oz. to 2 gallons warm 

 water. 



Pyrethrum (Insect Powder, Buhach). 



This powder is also called Dalmatian Insect Powder and Persian 

 Insect Powder. It is also, like hellebore, obtained from plants, being the 

 pulverized flowers of the botanical genus Pyrethrum. Value as an in- 

 secticide is due to the presence in it of an oil which is exceedingly poison- 

 ous to most insects, but practically harmless to human beings and the 

 higher animals. It can be used with impunity, therefore, and on account 

 of this fact is of special value. 



The oil which imparts the killing power (largely by contact with 

 the body of the insect) is very easily disseminated into the surrounding 

 atmosphere and thus lost. For this reason these powders must be fresh 

 and have 1 een kept in tightly sealed receptacles, else they will be inef- 

 fective. 



Application can be made in a number of ways : 



1. In solution : 1 oz. to 3 gallons of water. 



2. Dry : Apply while dew is on in the morning or after a rain. 



3. Dry, with dilution : Mix with some flour or other light powder 

 to any extent desired. Apply as 2. 



4. In fumigation : Dust over live coals ; for dealing with mosquitoes 

 and flies. 



FUNGICIDES. 



It has long been known that chemical compounds are useful in com- 

 batting fungous diseases. As early as 1807 it was found in France that 

 copper sulphate would prevent the germination of the spores of corn 

 smut, but this discovery, one of a very important nature, was not appre- 

 ciated or made known till a much later date. Sulphur was long used in 

 the same country, but was not nearly so energetic as desired. No ad- 

 vances were made, however, till 1882, when the value of the compounds 

 oi copper became known. Since then great strides have been made in 

 improved methods. 



As indicated above, copper is a very important ingredient in fungi- 

 cides. Nearly all the leading remedies contain it in some form or other ; 

 and so widely are its compounds used that we have come to term the 

 combinations in which it occurs as "The Copper-Salt Fungicides." 



