92 APPLE GROWING IN CALIFORNIA. 



CHAPTER XV. 



DISEASES OF THE APPLE. 



BLIGHT. 



(Bacillus amylovorus) 



This disease affects some varieties of the apple as badly as it does 

 the pear, and when trees in an orchard become affected the same reme- 

 dial measures must be applied as in the case of the latter, viz, pruning 

 out all diseased wood in roots, trunks and branches, being sure to cut 

 well below where any signs of the disease are noticed; and carefully 

 disinfecting all tools and cut surfaces with corrosive sublimate solution, 

 1 to 1000, after every cut. 



OAK ROOT FUNGUS. 



(Armillaria mellea.) 



Quite frequently apple trees are found rotted in the roots and at 

 the crown by this serious disease. The writer has in mind one orchard 

 visited early last spring, where tree after tree was diseased with this 

 fungus. Oaks had been growing on the land previous to the time of 

 apple tree planting and the stumps were still standing throughout the 

 orchard in many places. Surrounding these stumps a number of trees 

 were frequently found to be affected and great masses of toadstools, the 

 fruiting bodies of the fungus, were growing about the stumps and 

 apple trees. There is no cure known for this disease. 



APPLE SCAB. 



( Venturia incequaUs. ) 



The very destructive and commonly distributed disease known as 

 apple scab is familiar to practically every apple grower, and during 

 certain seasons a heavy loss is sustained from it, if nothing in the way 

 of spraying is done to control the fungus. 



It has a preference for certain varieties, others being more or less 

 resistant. The Yellow Newtown is one of the most susceptible to attack, 

 and spraying of orchards consisting of this variety should never be 

 neglected in sections where scab is prevalent. The Esopus is also very 

 susceptible in California, as well as many other varieties that might be 

 mentioned. Locality, of course, has considerable influence upon this 

 trouble, and in general the high altitude orchards in California suffer 

 most. 



Fig. 49 illustrates the appearance of this disease as it occurs on the 

 fruit, the well defined, grayish scabby patches, more or less roughened 

 where the skin has been broken through, being characteristic of the 

 advanced stage of the disease. 



This disease is due to a fungous organism which winters on the tree 

 and on fallen foliage. The plowing under of the leaves, before the 

 spores have a chance to get into the trees in the spring, is one of the 

 important things in connection with its control. 



