358 The Spraying of Plants. 



grown, the larvae are about half an inch in length. They feed 

 upon the foliage of the plants, and, if present in considerable 

 numbers, the foliage may be almost entirely devoured. During 

 June the insect pupates, but the adult does not appear until the 

 following spring. 



Treatment. The slugs are readily destroyed by the arsenites, 

 hellebore, or pyrethrurn. But some applications must neces- 

 sarily be made while the plants are in blossom ; this exposes 

 bees to the action of the poisons, and large numbers of these 

 insects are destroyed whenever enough poison to kill the slugs 

 is applied. Under such circumstances it is a question of killing 

 the bees or tearing out the plants. Hand picking might be 

 practiced, and if carried on for a year or two would greatly 

 reduce the numbers .of, the pest. Kerosene emulsion might also 

 be tried, the blossoms being touched as little as possible. 



ROSE. 



Black Spot; Leaf Blight (Actinonema Rosce, Fries). Descrip- 

 tion. During early summer the foliage of roses suffers from the 

 attacks of a fungus which causes the formation of irregular, 

 black spots upon the upper surface of the leaves (Fig. 86). 

 The spots eventually become nearly circular; their edges are 

 apparently fringed with delicate white, and later in the season 

 the affected leaves turn yellow, and fall to the ground ; at this 

 time the spots may be fully half an inch in diameter. Roses 

 grown indoors or in the open appear to be equally affected. 



Treatment. Fungicides containing copper will check the dis- 

 ease if the treatments are begun as soon as the buds open in 

 spring. Clear solutions are to be preferred. Removing and 

 destroying the affected leaves will also tend to lessen the 

 trouble. 



Leaf Spot (Cercospora roscecola, Pass.). Description. The 

 spots formed by this fungus are dark red or nearly black, the 

 edges of the well-defined areas being mostly of a red color. 

 The center changes to a grayish-brown color as the season 

 advances. Only those plants which grow out of doors are 

 affected, the foliage being the part generally attacked. 



Treatment. The treatment described under Black Spot, 

 above, is also recommended for this disease. 



