16 



CIRCULAR 3 6 5, U. S. DEPARTMENT OF AGRICULTURE 



plied at the times recommended in table 1, few scales can develop from 

 the small numbers of reproducing females present. For such sprays 

 it is recommended that emulsions prepared by formula 1 be diluted 

 at the rate of 1 part to 50 parts of water, and that the cold-pumped 

 emulsions (formula 2) be diluted 1 to 60. 



After the infestation of the camphor scale has been reduced to a 

 point where it can be controlled by dormant applications, one thorough 

 spraying each winter should be sufficient to hold it in check. The 

 New Orleans Parkway Commission has kept the scale generally under 

 control on city property in recent years by one dormant application 

 each year. 



Citrus trees present a different spraying problem than do orna- 

 mental and shade trees, because of the possibility of injury if freez- 

 ing weather follows within several weeks of winter applications. 

 Although some defoliation of shade trees may take place under these 

 conditions, they quickly recover when the spring growth puts out; 

 but if a freeze follows the application of an oil spray to citrus trees 

 it may cause a severe reduction in the crop the following season. In 

 the short time since the camphor scale has invaded the commercial 

 citrus-growing district of Louisiana, there has been no opportunity 

 to work out spray schedules for this district. Probably reliance 

 will have to be placed on summer applications. There were some 

 heavily infested groves in the Satsuma orange district of Alabama, 

 but intensive control measures have either eradicated these infesta- 

 tions or reduced the scale to negligible numbers. 



In spraying camphor-trees an effort should be made to cover the 

 branches and twigs thoroughly, without applying an excess of oil 

 to the leaves. Most of the females are on the wood, and these are the 

 scales that must be killed. Moreover, most of the oil taken up by the 

 plant is absorbed through the leaves, and this method of spraying 

 will give maximum effectiveness against insects and minimum danger 

 to the tree. In the case of citrus trees, the females develop on leaves, 

 fruit, and stems, and all parts should be given equal coverage. 



SUMMAKY OF SPEAYING EECOMMENDATIONS 



The recommendations as to sprays for controlling the camphor 

 scale with oil emulsions are summarized in table 2. 



Table 2. — Oil-emulsion sprays recommended for controlling the camphor scale 



Type of emulsion 



Dormant application 



Oil con- 

 centration 



Dilution 



Summer application 



Oil con- 

 centration 



Dilution 



Hot-pumped 



Cold-pumped 



Casein-lime spreader 



Percent 

 3.0 

 2.5 

 3.0 



Parts i 



Percent 

 1.2 

 1.0 

 1.2 



1 Parts of water to 1 part of emulsion. 



One dormant application should be sufficient to control the scale 

 except in cases of severe infestation. This may be applied between 

 November 15 and the time the buds burst in the spring. 



