1708 The Cornell Reading-Courses 



wilts and dies. No successful method of treatment is known. It will 

 help greatly in the control of the disease if the fruit canes are cut and 

 burned as soon as the fruit is gathered. In making new settings the 

 grower should use only plants from healthy patches. 



Crown-gall, or root-knot 



This is a bacterial disease that is often destructive, particularly to the 

 red varieties. It is detected by the large, irregular knots on the roots 

 and at the crown underground. The disease is contagious. 



Control. — The grower should avoid {planting on infested land, and 

 should never set plants showing the root-knots. Other than these two 

 precautions, no effective method of treatment is known. 



Red-rust 



The fungous disease known as red-rust, or yellows, is often serious on 

 both the black and the red varieties. In some sections of New York it 

 has made the crop unprofitable, while in other sections it is not found 

 at all. 



Control. — As soon as the disease appears in the patch the affected 

 plants should be rooted up and burned immediately, making sure that 

 all the roots are removed. If the disease is to be successfully checked 

 this method of eradication must be carefully carried out. 



INSECTS INJURIOUS TO RASPBERRIES 



The two insects that are injurious to the raspberry are briefly described 

 below and the methods of their control are given. These descriptions 

 are taken directly from the same sources as are those of the diseases. 



Sawfly 



The adult flies are black, with a dull reddish spot in the middle of the 

 abdomen above. They are about the size cf the house-fly, but are nar- 

 rower in shape and have four wings. The eggs are inserted into the 

 tissues of the leaf and a small brown patch appears on the leaf above 

 each egg. The eggs hatch after about a week. The larva;, which are 

 greenish in color and covered with rows of spines, feed on the tender 

 leaves in spring. They become full-grown by July, when they fall to 

 the ground and spin small cocoons beneath the surface of the soil. 



Control. — The insect is controlled by the application of weak solutions 

 of paris green or arsenate of lead, but these poisons should not be used 

 after the fruit is formed. Hellebore may be substituted, as this loses 

 strength rapidly after being applied. It may be dusted over the bushes 

 or steeped in water and sprayed on. 



