121 



ments, this emulsion was made up in exactly the same way. The same 

 difficulty of the emulsion rising to the top appeared, but was overcome 

 by diluting with a 1-1J4-50 iron sulfate-lime mixture instead of water. 

 Colloidal Clays. — Certain colloidal clays — Kaolin, Fuller's earth, 

 Bentonite, and several others — have been used successfully for making 

 cold-mixed oil emulsions. Those made with these clays were only tested 

 in a very limited way in the work here recorded, but very good results 

 were obtained. Work of the entomologists of the Bureau of Entomology 

 and in other states indicates that excellent emulsions can be made with 

 these colloidal clays. In some respects these are superior to most other 

 types of cold-mixed oil emulsions, and they are much cheaper than the 

 boiled soap oil emulsion. They are made up in the form of a thin 

 paste rather than a fluid, and this is objectionable for some uses. 



VEGETABLE-OIL-SOAP EMULSIONS 



In treatments Nos. 54, 53, 56, 80, 81, and 83 of Table IX (see p 

 115), the results of spraying with emulsions made with vegetable-oil soap 

 as a substitute for fish-oil soap are given. They are apparently just as 

 effective scalecides as the emulsions made with potash-fish-oil soap, and 

 are slightly cheaper. 



Summer Sprays with Oil Emulsion, 1923 and 1921 

 foliage tests, summers of 1923 and 1924 



Oil emulsions had, of necessity, been used for a number of years on 

 citrus trees while in foliage. During the summer of 1932, they were 

 used on apple foliage with little or no burning in experimental work by 

 the Bureau of Entomology in the Bentonville, Arkansas, section, and in 

 work done by this office near Olney, Illinois. During the summer of 

 1923, foliage injury tests were made at Carbondale with a number of 

 diflerent trees, shrubs, and other plants. Apple, cherry, grape, lilac, mul- 

 berry, maple, peony, peach, pear, potato, rose, tomato, and walnut were 

 sprayed during June on clear hot dry days, the temperatures ranging 

 from 89° to 91° F., with 2% strengths of (1) boiled fish-oil-soap emul- 

 sion, (2) the same with Bordeaux mixture, 4-1-50, and (3) cold-mixed 

 Bordeaux oil emulsion, and the only seen injury to plants in these tests 

 was severe burning of the foliage on potato and tomato, and a slight 

 blackening of a few leaves on rose and maple. 



On cooler cloudy and humid days, with temperatures ranging from 

 80° to 83°, the following were injured. 



With boiled fish-oil-soap emidsion alone 



Peach Slight to defoliation 



Pear 50% of leaves specked black 



Tomato 15% of leaves partly blackened 



Rose 40% of leaves slightly burned 



Walnut 50% of leaves peppered with black dots 



Maple 2% of leaves slightly blackened 



