Methods of Control 363 



// is essential when arsenicals are used to see that 

 they are correctly labeled, and kept under lock and key, 

 as they are poisonous to man and animals. 



Hellebore or white hellebore is somewhat less 

 dangerous than the arsenicals. However, it loses 

 its insecticidal value by being exposed to the air. 

 It is a specific against slugs. 



(b) Contact Poisons. All the tobacco or nicotine 

 products sold principally as extracts or powders be- 

 long to this class. A common brand much used is 

 the preparation known as "Black leaf 40," diluted 

 I part to 700 or 800 of water. An addition of 

 ivory soap at the rate of two bars to each 100 

 gallons of the solution increases its effectiveness 

 by making it spread out better. Aphine, sulpho 

 tobacco, and a number of other products found on 

 the market are usually valuable as contact poisons 

 if properly tested out and guaranteed by the deal- 

 ers. Ordinary laundry soap, one pound to seven 

 gallons of water, is very effective against all soft- 

 bodied sucking insects. 



FUNGICIDES 



These are poisons used to control fungous diseases. 

 As previously stated, some parasitic fungi live on the 

 surface of the leaves and stems and are therefore 

 easily controlled. An example of this is the powdery 

 mildew. Other fungi, and these are in the larger 

 majority, are those which live parasitically within 

 the tissue of the host, and therefore cannot be reached 



