ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



11 



CONTROL 



Ordinary infestations may be controlled by a single thorough appli 

 cation of lubricating oil emulsion or lime-sulfur solution during the dor 

 mant season. More than 1 year may be 

 required to bring very heavy infestations 

 under control, but this may be accom- 

 plished by spraying the trees twice in 

 one season. If two applications are 

 made, one should be made in the fall, 

 if possible, and the other in the spring. 

 Not more than one application of oil at 

 dormant-season strength should be made 

 in a year, and if two applications for the 

 scale are contemplated, the first should 

 be of lime-sulfur solution. The second 

 may be either oil emulsion or lime-sulfur. 



The question of which material to use 

 depends on what other insects are on the 

 trees at the time the spray is applied. 

 Oil sprays are very effective against the 

 eggs of red spiders, treehoppers, and the 

 fruit tree leaf roller, and against newly 

 hatched aphids, and should be used if 

 these eggs or insects are numerous. 



Otherwise, the lime-sulfur solution is just as satisfactory. It is often 

 desired to control the pear leaf blister mite, on pear trees, and for this 



Figure 8. — San Jose scale : Males 

 and females. X 8. 



lime-sulfur 

 is preferable 



Figure 9. — Apple 



buds in proper condition for 

 mant spray. 



dor- 



purpose 

 solution 

 (p. 71). 



This solution is per- 

 haps safer for use dur- 

 ing the delayed dor- 

 mant period than oil 

 emulsion, although a 

 sudden onset of warm 

 weather following its 

 application will at 

 times cause a drop- 

 ping of the fruit buds. 

 The safest procedure 

 is to use these ma- 

 terials only while the 

 trees are still dormant 

 (fig. 9). Preferably 

 the spray should be 

 applied after the prun- 

 ing is finished, as less 

 material is required 

 then, and the more 

 heavily infested limbs 

 may often be removed 

 before spraying. It 

 mav sometimes be nee- 



