101 



all likely to be infested at the time, or to become infested before the 

 end of the nursery season, is fumigated with hydrocyanic acid gas 

 before it is sent out from the nursery. By these precautions the dan- 

 ger of distributing the scale on nursery stock is reduced to a mini- 

 mum, but they nevertheless do not afford complete protection because 

 the scale is so inconspicuous that the most careful inspector will some- 

 times overlook it. The buyer should consequently inspect carefully all 

 trees and shrubs purchased, and, as an additional safeguard, should 

 either fumigate them with hydrocyanic acid gas or dip them in, or spray 

 them with, a solution of lime and sulphur — to be described later — 

 before setting them out. 



In parts of the country where the San Jose scale is prevalent, 

 nursery grounds should be placed half a mile or more from orchards 

 or other trees which may harbor the scale. Even a quarter of a mile 

 will afford much protection, if not absolute security to the nursery 

 stock, especially if near-by orchards are properly treated annually. 

 The common practice of growing nursery trees on vacant city lots or 

 close to infested orchards should be discontinued. Whenever trees, 

 shrubs, or hedges in or near growing nursery stock are found to be 

 infested with the San Jose scale they should be at once removed. 



This insect is very often brought into nurseries on scions taken 

 from infested trees ; and these should not be used if it can be avoided. 

 If used, they should be very carefully inspected, the infested sticks 

 should be discarded, and all the rest fumigated ; and as a further pre- 

 caution, the stock should be thoroly sprayed in spring while still dor- 

 mant. 



To guard against an introduction of the scale from infested nur- 

 series, nurserymen should be very careful to buy only from firms which 

 have the reputation of handling clean stock; and as an extra precau- 

 tion stock bought elsewhere should be fumigated, unless the buyer is 

 sure that it is clean. 



To avoid trouble with the San Jose scale in cities and towns, only 

 trees and shrubs that are not subject to its attack should be chosen 

 for lawns and parks. A yard or park containing only trees and shrubs 

 of the second and third lists given above will seldom, if ever, sufifer 

 any serious injury from the San Jose scale. 



Artificial Means of Control. — The most effective way to destroy 

 the scale is to grub out the tree or shrub which it infests or to cut it off 

 three or four inches below the surface of the ground. If the infested 

 plant is not cut off low enough, some scales will probably be left on the 

 stump, and from these, shoots which grow up around the stump will 

 become infested. 



