28 STATE HORTICULTURAL SOCIETY. 



CHEMISTRY OF INSECTICIDES AND FUNGICIDES. 



BY PROF. R. C. KEDZIE, AGRICULTURAL COLLEGE. 



I regret that I had agreed to speak on this subject, because one of our 

 students has agreed to prepare a thesis upon it and I am a little afraid I 

 shall tread on his ground. I am somewhat in the position of the Sunday- 

 school pupil. It was his first day and he was a little bashful; and the 

 teacher, looking at him with a somewhat stern expression on his counte- 

 nance, asked, "Who first brought sin and death into this world with all 

 its woes?" He answered, "I did, ma'am, but I will never do it again." 



Somebody proposed the use of Paris green poison for the potato bug. 

 It is a very effective poison, and if properly used will answer this purpose 

 very effectively. But there is a better form of it than the one commonly 

 used. It is a material that could be much more easily prepared. It is 

 more of the nature of Scheele's green. This Paris green I am using is 

 used very largely as a paint and has consequently a large demand which 

 the Scheele's green has not. Next after the use of Paris green and 

 Scheele's green came corrosive sublimate or mercuric chloride. The 

 great objection to this is it is costl3\ 



I might lay down these three principal requisites for an insecticide and 

 fungicide: It must do the work thoroughly, it must be safe, not injure the 

 plant, and must be cheap. The use of Paris green and Scheele's green 

 anstvers the first and second conditions, but unfortunately it does not ful- 

 fil the third condition. It is a somewhat costly material, and the thing 

 that now troubles us is that the price has lately increased and promises 

 to increase still more. The law in this state requiring use of insecticides 

 and fungicides commands the use of such materials. A trust is forming 

 and bids fair to control the price for some time to come. This trust, as I 

 am informed by a leading dealer in Lansing, has control entirely of the 

 Paris green market in this country. While Paris green can be imported 

 from abroad, the cheapest they can sell it is twenty-six cents per pound 

 in quantities of half a ton, and in less than that quantity, twenty-eight 

 cents. It retails at fifty cents per pound, and may go up to sixty. If a 

 dealer makes it, the trust announces it will sell none to him thereafter; 

 he must buy of the trust or the trust will sell none to him at all. 



To digress a little we may say we have a large class of poisons usually 

 used for this purpose — the commonly recognized bine vitriol, the car- 

 bonate of copper, bought at retail for forty cents, and the other for sixty 

 cents per pound. The poisonous property of the copper is about twice 

 as great in the carbonate as it is in the suli)hate. We have a large num- 

 ber of other substances which are used for the purpose. Some recom- 

 mend thnt arsenate of lead be used in place of the Paris green. We may 

 get the material in the form of an arsenate of lend or arsenife of lead. 

 The mnterinl is very ensily formerl. We may use the lead salt or the zinc 

 salt which I form before you; equally valuable, equally useful for a poi- 

 son. Tlif'v must be, however, in the form of a neutral salt, insoluble in 

 water, and not form a precii)itate with tests for arsenic; but here we get 



