20 HORTICULTURIST'S RULE-BOOK. 



PEAR TWIG-BEETLE. See under PEAR. 



PLUM-CURCULIO (Conotrachelits nenuphar, Herbst.). 

 Beetle; punctures the fruit and causes it to become dis- 

 torted. 



Remedies. Arsenites. Often recommended (but of 

 doubtful efficiency) to plant plum trees at intervals 

 throughout the orchard to attract the curculio, and fight 

 the insects on the plums. See under PLUM. Jarring onto 

 sheets is probably the surest procedure. 



RAILROAD-WORM. See APPLE-MAGGOT. 



ROOT-LOUSE, "AMERICAN BLIGHT" of England (Schizoneura 

 lanigera, Hausm.). A minute insect which causes swell- 

 ings upon the roots of the tree, impairing its vitality, or 

 killing it. In another form the insect attacks the young 

 branches. It is then conspicuous from its cottony cover- 

 ing. The treatment for aphis is useful here. 



Remedies. Hot water. Corrosive sublimate wash. 

 Scalding hot water may be poured on the bare roots of 

 trees standing in the soil, or nursery stock may be dipped 

 in water having a temperature of 120 to 150. Kerosene 

 emulsion or tobacco dug in about the tree. Infested nursery 

 trees should be dipped in kerosene emulsion root and top 

 before they are set in the orchard. Mulching about trees 

 is said to bring the lice nearer the surface. 



ROSE-BEETLE. See under ROSE. There is practically no 

 remedy for the rose-beetle on large orchard trees. Ravages 

 can be prevented, to a large extent, by the lime spray and 

 the emulsions. Very heavy applications of Bordeaux mix- 

 ture sometimes act as a repellent. 



ROUND-HEADED BORERS (Saperda Candida, Fabr., and S. cre- 

 tata, Newm.). Larva, an inch long when mature, bores 

 into the tree. It remains in the larval state three years. 



Preventive. Soap and carbolic acid, and various other 

 washes applied early in June and July. 



Remedies. Dig out borers in the fall. Force some 

 caustic material, as soda-wash, into the burrows by means 

 of a small syringe. Insert a wire into the holes. The only 



