I38 MAINE AGRICULTURAL EXPERIMENT STATION. I902. 



The material is found to contain several things, of which 

 Paris green is the poison, nitrate of potash the plant food, and 

 carbonate of copper the germicide. 



Analysis of the material shows it to have substantially the 

 following composition : 



Calcium sulphate (land plaster), 88.0 per cent. 



Iron ochre, 2.0 per cent. 



Nitrate of potash, 4.5 per cent. 



Paris green, . 2 . 5 per cent. 



Carbonate of copper, 2.0 per cent. 



Water and undetermined, 1.0 per cent. 



The Paris green in these goods is the only thing of much value 

 to the potato grower. The plaster and nitrate of potash contain 

 plant food, but the benefit to be obtained from small applications 

 above ground is inconsiderable. 



The goods sell according to the advertisements at prices rang- 

 ing from five to ten cents per pound, according to the size of the 

 package. Its high cost comes chiefly from the fact that it is 

 put up in small packages. A mixture of Paris green and plaster 

 which will equal Kno-bug as an insecticide can be made by the 

 farmer for very much less cost. 



In a newspaper bulletin issued last June by the Station, Kno- 

 bug- was called a fraud. It was so called because it claimed to 

 be better than Paris green and safer to use as an insecticide, when 

 it depended upon Paris green for its value as an insecticide ; 

 because it claimed to prevent blight, for which carbonate of cop- 

 per is not a specific : and because it was claimed to prevent scab, 

 which cannot be done by any treatment of vines. The manu- 

 facturers, Carpenter-Morton Company, Boston, state that they 

 acted in good faith and had no intention of fraud in putting the 

 goods on the market, and that chemists in whom they had confi- 

 dence advised them that its ingredients would produce the results 

 claimed. The coming season they intend to make no claim for 

 Kno-bug as a fungicide, and will base their reasons for its sale 

 upon its merits as an insecticide. 



A field test of Kno-bug was made by the Station in 1902 chiefly 

 to ascertain if it had value as a fungicide. The first application 

 was made when the potatoes were about a foot high. This piece 

 had been previously sprayed with Bordeaux mixture and arsenate 

 of lead. No further application of Bordeaux mixture was made 



