12 



for lime-sulphur wash which would not be justified where but a few 

 plants were involved. For a lew ]ilants it would be better to use 

 some one of the i)repared washes put up by manufacturers. In fact, 

 m.any large orchardists prefer to use sprays of this class in prefer- 

 ence to making the washes at home. The ])ossibility of injury to 

 tiie trees from the sprays must also be borne in mind. All treat- 

 ments, if possible, should be made during the dormant ])eriod (this is 

 to say, in late fall or early sjoring, or even during the winter in mild 

 climates), since at this time washes may be applied at much greater 

 strengths than when the trees are in foliage. The aim is to use the 

 wash about as strong as the tree will stand, thereby securing the 

 maximiun killing effect upon the insects. Used in this way the 

 washes of the petroleum or kerosene series are most likely to cause 

 injuiy to tlu> fruit buds and tender twigs, and the lime-sulphur 

 washes least likely to do so. Whale-oil-soap s})rays as recommended 

 for dormant trees are comparatively safe, though reports are at 

 hand of injury to fruit buds, especiiilly from fall a])j)lications. Stone 

 fruits, such as peach, ])him, etc., are more suscc})til)le to injiuy from 

 sprays than ai)])le and ])ear, and on the former the lime-sulphur 

 si)rays should always be used. Petroleum and miscible oils are 

 more frequently used on apple and ])ear, and owing to their s})read- 

 ing and ])enetrating qualities are })erhai)s more effective in destroy- 

 ing the scales on the terminal twigs, which are infested to a greater 

 extent in the case of these fruits. The several spi-ays in use ma}^ be 

 considered under the following headings: (1) Lime-sulphur wash 

 series; (2) })etroleum oil series (including miscible oils), and (3) soap 

 wash series. 



LIME-SULPIIUR WASHES. 



For many years the cooked lime-sulphur wash has been the main 

 reliance in the control of the scale. It is made according to the fol- 

 lowing formula: 



Stone lime pounds. . 20 



Sulphur (flour or flowers) do 15 



Water to make gallons . . 50 



Heat in a cooking barrel or vessel about one-third of the total 

 quantity of water required, \yiien the water is hot adil all the lime 

 and at once add all the sulphur, which previously should have been 

 made into a thick paste with water. After the lime has slaked, about 

 another third of the water should be added, preferably hot, and the 

 cooking should be continued for one hour, when the final dilution 

 may be made, using either hot or cold water, as is most convenient. 

 The boiling due to the slaking of the lime thoroughly mixes the 

 ingredients at the start, but subsequent stirring is necessary if the 

 wash is cooked by direct heat in kettles. If cooked by steam, no 



[Cir. 1241 



