INJURIOUS INSECTS. 41 



Remedies. Persistent syringing with water will gen- 

 erally destroy them, if the spray is applied to the under 

 surface. Fumes of sulphur. Sulphide-of-soda wash. 

 Kerosene emulsion as for MITES. 



Rhubarb. RHUBARB-CURCULIO (Lixus concavus, Say). A 

 grub three-fourths inch long boring into the crown and 

 roots. It also attacks wild docks. 



Remedy. Burn all infested plants, and keep down the 

 docks. 



Root-Gall, Crown-Gall. A widespread disease, of which 

 the cause is wholly unknown. It occurs upon the peach, 

 apple, pear, raspberry, blackberry, and other plants. The 

 swellings are hard and woody, and appear both at the 

 crown of the plant where they sometimes attain the size 

 of one's double fists and on the small roots. 



Remedy. Nothing is surely known in the way of 

 remedy except to destroy badly infested trees. It is rec- 

 ommended to dig away the earth, cut off or pare off the 

 knots, and to paint the wounds with Bordeaux mixture. 

 Nursery trees should be inspected for the galls. 

 Root-Knot (Heterodera radicicola, Miill.). A disease charac- 

 terized by the knotting and contortion of the roots of the 

 peach, orange, and many other plants. The knots are mostly 

 rather soft swellings, and on the smaller roots. It is usually 

 most destructive on the peach. It is caused by a nematode, 

 or true worm. Gulf States. Attacks greenhouse plants in 

 the north. 



Preventive. Plant non-infested plants in fresh soil ; 

 bud into healthy stocks. Fertilize highly, particularly with 

 potassic fertilizers. Set the trees eight or ten inches deep 

 in high and dry soils. Infested small trees may be 

 remedied, in part at least, by transplanting them into 

 highly manured holes which have been prepared contiguous 

 to them. Does not live in regions where the ground 

 freezes deeply. If it is feared in greenhouses, see that the 

 soil has been thoroughly frozen before it is used. White- 

 wash the benches. See ROOT-GALL. 



