PROTECTING PLANTS 191 



kill by destroying the body of the insect. Of the former, there 

 are three materials in common use — Paris green, arsenate of 

 lead, and hellebore. Of the latter, the most usual at present 

 are kerosene emulsion, miscible oils, and the lime-sulfur 

 wash. In the last year or two, the lime-sulfur preparations 

 have been greatly perfected, and they are now becoming popu- 

 lar in commercial work not only for insects but for certain fungi. 



Sprays for fungi usually depend for their efficiency on some 

 form of copper or sulfur, or both. For surface mildew^, as 

 grape mildew, dusting flowers of sulfur on the foliage is a pro- 

 tection. In most cases, however, it is necessary to apply 

 materials in liquid form, because they can be more thoroughly 

 and economically distributed, and they adhere to the foliage 

 better. The best general fungicide is the bordeaux mixture. 

 It is generally, however, not advisable to use the bordeaux 

 mixture on ornamental plants, because it discolors the foliage 

 and makes the plants look very untidy. In such cases it is best 

 to use the ammoniacal copper solution, which leaves no stain. 



In all spraying operations it is especially important that the 

 appHcations be made the very moment the insect or disease is 

 discovered, or in the case of fungous diseases, if one is expecting 

 an attack, it is well to make an application of bordeaux mix- 

 ture or lime-sulfur even before the disease appears. When the 

 fungus once gets inside the plant tissue, it is very difficult 

 to destroy it. For ordinary conditions, from two to four spray- 

 ings are necessary to dispatch the enemy. In spraying for 

 insects in home gardens, it is often advisable to make a sec- 

 ond application the day following the first one in order to 

 destroy the remaining insects before they recover from the 

 first treatment. 



There are many kinds of machines and devices for the ap- 

 phcation of sprays to plants. For a few individual specimens, 

 the spray may be applied with a whisk, or with a common garden 

 syringe. If one has a few trees to treat, however, it is best to 



