10 Department Circular 263, V. S. Dept. of Agriculture. 



February, 1922. Follo^Ying this initial venture, plants at two other 

 points in northwestern Arkansas began the manufacture of this 

 insecticide. About 1,000 barrels of oil emulsion were used commer- 

 cially, taking the place of approximately 4,000 barrels of concen- 

 trated lime-sulphur solution. 



A 2 per cent emulsion, or 6 gallons of stock in a 200-gallon spray 

 tank, was the streng-th used by practically all growers. The period 

 during which oil emulsion was applied for the dormant spray in 

 various orchards extended from the middle ol February until after 

 the buds had opened, some growers even using it as late as the pinlv 

 spray. Growers who made the application late secured unusually 

 good control of the green apple aphis in addition to killing the 

 scale. In fact, many growers later used the oil spray against the 

 green aphis when they found that this insect, usually of little eco- 

 nomic importance in this section, was causing considerable damage. 



A very satisfactory control of the scale in commercial orchards 

 was obtained with the 2 per cent emulsion in practically all instances. 

 The scale was brought under control in orchards in which it had been 

 increasing gradually in previous years in spite of dormant spraying. 

 While the scale was by no means eradicated, growers felt more 

 optimistic of their ability to hold it in check than heretofore. Ex- 

 aminations of twigs from a large number of oil-sprayed orchards 

 showed just as good kill of scales as was effected in the experimental 

 spraying. Occasionally a few live scales were found in protected 

 places, such as crevices on the fruit spurs or in deep depressions or 

 cracks of old hail bruises. Of course, some trees were not covered 

 completely with the spray, and missed spots showed live scales. 



SUMMER TREATMENTS WITH OIL EMULSION. 



Tests with lubricating-oil emulsion were made during the summer, 

 from the time the young scale crawlers of the first generation ap- 

 peared until the fruit was harvested. Only a partial control of the 

 scale w^as accomplished at this season in any of the tests, although 

 oil emulsion of the same strength was used as for the dormant spray. 

 The high summer temperatures caused the spray solution to evaporate 

 so quickly that only the most tender stages of the insect were killed. 

 All the crawling scales that were hit by the spray were killed, as well 

 as the newly settled young. Many of the young which had not 

 emerged from under the scale covering of the adult female were also 

 reached by the oil spray, and in such cases the young near the exit 

 hole were killed, which prevented those that were not touched from 

 escaping. Some half-gTOwn scales and a few full-grown females 

 w^ere killed l)y the summer sprays. In the course of a week or 10 days 

 following the spray, however, young crawlers would be found emerg- 

 ing and settling down. 



Many growers used oil emulsion in the standard summer Bordeaux 

 sprays, and there is no doubt that the scale was held in check to such 

 an extent that much spotting of fruit and damage to limbs was pre- 

 vented. Much of the scale was cleaned ofl' the fruit by the summer 

 sprays. Most of the live scales left on such fruit were found deep in 

 the calyx or stem cavities, where the spray solution failed to reach 

 them. 



