Combination Insecticides and Fungicides. 



The cost of spray materials is usually insignificant as com- 

 pared with the cost of application. One way of reducing the 

 latter expense is by combination spraying; that is, by mixing 

 two or more spray materials and applying them together. In 

 mixtures of this sort marked chemical changes may take place 

 which render the mixtures wholly unfit for use. On the other 

 hand, the original ingredients may remain unchanged or may 

 be improved by the combination. The following table gives 

 the comparative value of some such combination sprays : — 



Fungicide 

 (Bordeaux 

 Mixture). 



Contact Insecticides. 



Soap. 



Nicotine 

 Sulphate. 



Stomach poisons: — 

 Paris green, . 

 Lead arsenate, 



Contact insecticides: 

 Soap, 

 Nicotine sulphate. 



Better. 

 Efficiency reduced. 



Questionable. 

 Efficient. 



Injurious. 

 Questionable. 



Better. 



Injurious. 

 Efficient. 



Better. 



By reference to the table it will be seen that mixtures of 

 soap with lead arsenate or Bordeaux mixture are questionable 

 combinations. Soap is used here only to increase the spreading 

 and adhesive qualities of these sprays. In the majority of 

 cases lead arsenate or Bordeaux mixture may be used alone, 

 as these sprays are markedly adhesive in themselves. How- 

 ever, on such plants as cabbages, asparagus, celery, etc., the 

 waxy bloom and smoothness of the foliage repels these sprays, 

 causing them to gather in large drops and drip from the plants 

 so that a thorough distribution, on which the success of the 

 treatment depends, is not secured. Therefore when spraying 

 such plants the adhesiveness of lead arsenate and Bordeaux 

 mixture is increased by the addition of a "sticker," or soap, 

 which insures a more uniform application over the foliage. 



The addition of Bordeaux mixture to arsenate of lead reduces 

 the killing power of the latter about one-third, but it is cheaper 



