72 BULLETIN 351, U. S. DEPARTMENT OF AGRICULTURE. 



In all cases the plats were first carefully inspected and typical 

 branches were marked with tags which stated the condition of the 

 scales and the nature of the infestation. About 10 per cent of the 

 tagged trees were then left unsprayed and the results were taken by 

 an individual examination of the scales upon the tagged branches. 

 Before taking the scale count all winter killed and parasitized scales 

 were removed from the branches, so that the count includes only 

 scales that were alive and normal at the time the sprayings were 

 made. The result of miscible-oil sprays became evident in a very 

 few days after the application, when the dead scales began to drop. 

 Because of the dropping of the scales it was found that counts 

 should be made within one week after the application to show 

 the true mortality. The result of delaying the count is well illus- 

 trated by a comparison of experiments 1 and 2. So far as the counts 

 show these applications were equally effective, but in the second 

 experiment there was an interval between the application and the 

 count, and some of the dead scales had disappeared, thus making the 

 mortality appear lower than it was. In comparing experiments 1 

 and 2, it appears that miscible oil at the strength of 1 gallon of oil 

 to 18 gallons of water, when applied in the spring, is moderately 

 effective against the scale, without producing injury to the trees, 

 and that when applied in the fall it is nearly as effective against the 

 scale, but produces severe injury to the trees. 



Experiment 3 was made to determine the effect of using the regu- 

 lar lime-sulphur nozzles in applying miscible oil, and the plat was 

 sprayed by the regular orchard force without oversight. Of the two 

 counts made in experiment 3, the first represents the true mortality 

 and the second shows only the condition of the scales present on 

 May 2, when there were fewer dead scales than on April 23, due to 

 then falling in the interval between the counts. The results in 

 experiments 1 and 3 show clearly the necessity for using nozzles 

 with smaller apertures and for making a more thorough application 

 than is customary when applying dormant lime-sulphur sprays. 



Experiments 4, 5, 6, and 7 show the effects of applying miscible 

 oil hi the winter, at a time when both the lecanium and the trees are 

 dormant. When these applications were made the day was mild 

 and calm, with the temperature well above freezing. A power out- 

 fit was used and the trees were sprayed until there was a slight 

 dripping from the branches. The time between the date of apply- 

 ing these sprays and the date of making the scale count was rather 

 too long to give the full mortality. The error, however, was small 

 and was estimated at less than 5 per cent. These four experiments 

 were all ineffective. Experiment 4 was accompanied by severe 

 injury and experiments 5, 6, and 7 showed spray injury and failed 

 to control the scale. It is therefore concluded that miscible oils are 



