July 1, 1925 
Colbidal Clays as Emulsifiers for Mineral Oils 
63 
Again, on May 11, 1923, 13 seedling orange and grapefruit trees 
near Orlando, Fla., were sprayed with kaolin emulsion at the rate of 
9 quarts to 150 gallons of water, or approximately 1 per cent oil in the 
diluted spray. The grapefruits were nearly inches in diameter, 
and the oranges about iy inches. The sun was bright and the 
temperature approximately 80° F. The emulsion mixed perfectly 
with the lake water and there was no residue in the tank when the load 
was finished. The spray collected in large drops on the fruit and 
foliage and they appeared to be covered with free oil. A few minutes 
after spraying spots (commonly called “shadows”) with an oil-soaked 
appearance developed where the drops of spray had collected. Some 
of the spots caused by the oil had not left the fruit as late as August 1. 
Such spotting frequently occurs on citrus following oil sprays, but if 
not too severe it usually disappears long before the fruit takes on the 
color of maturity. 
Extensive field tests were made with kaolin emulsion through the 
entire season of 1923. Many thousand gallons were used in combi¬ 
nation with various strengths of Bordeaux mixture during the scab 
and melanose spraying seasons, and in every case equally satis¬ 
factory results were obtained as with soap emulsion, and no injury 
followed. It was also used extensively m combination with lime- 
sulphur solution and dry lime sulphur during late June and early 
July to kill scale insects and rust mites following Bordeaux oil emul¬ 
sion applied for scab or melanose control. 
As a general thing it gave satisfactory results in controlling scale 
insects and rust mites, but in some cases considerable injury followed. 
The kaolin emulsion alone has never caused any damage different in 
appearance or extent from that following soap emulsion applied under 
similar conditions, and in only a few instances has lime-sulphur 
solution caused damage. There seems to be a greater liability to 
damage when an emulsion is combined with lime-sulphur solution 
than when the two are applied separately. 
Fuller's earth was used with excellent results by a large fruit 
company on several acres of oranges and grapefruit during 1923 and 
on about 400 acres during 1924. It was used with “hard” or “sul¬ 
phur” water from deep wells, and it mixed better than any emulsion 
ever before used by this company. They used a heavy oil diluted to 
iy z per cent and got some oil burn. The oil concentration was 
reduced to 1 per cent and still some burn developed. They then 
added 2 pounds of hydrated lime to each 50 gallons of diluted spray 
and thereby practically eliminated the spray injury. 
KAOLIN AND FULLER'S EARTH EMULSIONS WITH CALCIUM 
CASEINATE 
Both kaolin and fuller's-earth emulsions when applied on citrus 
foliage have the appearance of not spreading very well, but, as will 
be shown later, this appearance is entirely deceptive. To overcome 
this apparent objection, several experiments with calcium caseinate 
were tried. On May 23, 1923, six orange trees were sprayed, using 
kaolin emulsion 1 % per cent in the diluted spray and calcium case¬ 
inate at the rate of 1}4 pounds to each 50 gallons of water. This 
spray spread over the leaves and fruit uniformly and did not collect 
in drops on the fruit except on the lower side. On August 27 two 
50-gallon tanks of kaolin emulsion and two tanks of fuller's-earth 
