368 Diseases of Truck Crops 



done, is effective in controlling or in keeping in check 

 all the pests which attack truck crops. In combining 

 a fungicide with an insecticide, we may accomplish 

 two aims in one operation. The various spray mix- 

 tures which may or may not be combined are in- 

 dicated by Cooley and Swingle 1 as follows: 



Tobacco Bordeaux 

 extracts mixture 



Paris green yes yes 



Arsenate of lead yes yes 



Arsenite of zinc (ortho) yes no 



Arsenite of lime yes yes 



Each of these preparations is mixed and applied just 

 as if it were used alone. A combination of the am- 

 moniacal copper carbonate with an arsenate would be 

 unsafe, since the ammonia renders the arsenic more 

 soluble, and hence may result in the burning of the 

 foliage. However, it may be safely mixed with the 

 tobacco products. 



Recent investigations by Professor Safro, Entomo- 

 logist to the Kentucky Tobacco Products Co., indi- 

 cate that * ' Black leaf 40 ' ' may be used in combination 

 with such spray chemicals as lime-sulphur, arsenate 

 of lead, arsenite of zinc, and iron sulphate, for con- 

 trolling sucking and chewing insects and fungous dis- 

 eases, the soap in this case being omitted. Professor 

 Safro 's work further claims that " Black leaf 40 " may 



1 Cooley, B. A , and Swingle, D. B., Montana Agr. Expt. Sta. Circ. 

 17: 



