86 THE FRUIT GROWER'S GUIDE. 



DISEASES. 



Though the apricot is subject to few diseases, it suffers more from that termed 

 " branch- dying " than do most fruit trees. Grown under glass or against walls outdoors, 

 apricot trees lose branches suddenly, often when laden with fruit ; leaders collapse in 

 young trees, main branches perish here and there in trees just coming in to profit, 

 while those having covered their allotted space lose one branch after another till the 

 trees are spoiled. Sometimes the disease is seen to be gum ; in other cases there is no 

 outward indication of that disease beyond shrinkage in the branch and smallness of 

 foliage above the point of collapse ; while in some instances there is no visible sign of 

 damage except a few small holes in the branch where it dies off. These symptoms, how- 

 ever, equally with the first, afford evidence of gum disease closing the channels of the 

 wood and thus preventing the nourishment of the branch above the point of infestation ; 

 in fact, 99 per cent, of the cases of "branch-dying " are due to gum disease, caused by 

 the fungus Coryneum Beijerincki. The cultural inducements to gumming are 

 planting in over-rich soil, the production of gross wood, the severe cutting back of the 

 growths in summer so as to suddenly expose the branches to the sun whereby the 

 bark is hardened, and a sappy condition of the wood which then suffers from frost, 

 combined with severe winter pruning. Careful culture is the best means of preventing 

 the evil in question, and to this end the cultural instructions have special reference. 

 Gum disease, Coryneum Beijerincki, is fully treated on page 234, Vol. I. 



Clean culture is recommended with the removal jof infested parts, spraying before 

 the buds swell with a solution of sulphate of copper, 1 pound to 25 gallons of water; 

 and subsequently with carbonate of copper in suspension, 1 ounce first well stirred in 

 a- small quantity of water, and the mixture thus formed added to 12 1 gallons of water, 

 spraying first when the fruit is the size of horse-beans, next in 12 to 15 days, and 

 again, if needed, 15 to 21 days after the second application. Ammoniacal carbonate of 

 copper solution, Vol. I., page 241, or modified Eau Celeste, Vol. I., page 242, may be used 

 for spraying, first ascertaining, by experiment on a small scale, the safe strength at which 

 to apply them to the whole tree without injury to the foliage and fruit. 



Mildew (Oidium Species). The Oidium of the apricot is probably an early condition 

 of a fungus named Podosphoara clandestina, or P. oxyacanthse, a common parasite 

 of the hawthorn. It is a powdery mildew, with a life history similar to that explained 

 under "Mildew," Vol. I., page 245. It infests the leaves and young growths of the 

 apricot, causing the former to curl and the latter to be distorted. Culturally mildew 



