240 



THE FRUIT GROWER'S GUIDE. 



Fig. 65. CLADOSPOBTOM DENDEITICUM ON 

 APPLE LEAF. 



Showing effects of infection. Detached small 

 dots size of black spots when discernible by the 

 naked eye ; black patches and blotches varied 

 et:iges of the fungus growth. 



often cover a large part of the surface of the leaf. The spawn threads in the leaf are 



somewhat different in form from those in the 

 fruit, and do not always develop brown spores 

 (conidia), but the short cells of the " clnbs " 

 (stroma) may break off and act as spores, and 

 these finding suitable germinating media, as 

 tender shoots, young leaves, and growing fruit, 

 push out spawn threads, and reproduce the scab 

 fungus. This form is well represented in the 

 engraving Fig. 66. 



Sometimes the fungus grows on all parts of 

 the flowers. This is usually disastrous, as it 

 often prevents their setting, while the fruits 

 which form cannot swell freely, through the foot- 

 stalks being affected, and consequently several 

 of them drop. This form of Cladosporium is more, if not entirely, confined to pears 

 (see " Cracking in Pears "). 



In combating scab (and all diseases) it is necessary that none of the essential 

 conditions to a tree's health be ignored, but 

 whatever is lacking for its restoration to and 

 maintenance in normal health must be afforded. 

 Lifting affected trees, and otherwise attending 

 to the deficiencies or superfluities of soil con- 

 stituents and general management, as set forth 

 under " Canker," are applicable to trees afflicted 

 by scab. 



The seventh annual report of the Agricul- 

 tural Experiment Station of the University of 



"Wisconsin Contains a report by Mr. E. S. Groff, Showing closely-massed condition of mycelia 



and " fruit " of fungus at the extremities of spawn 



On the "Prevention of Apple Scab." In a threads. The short cells of the " clubs " one- 

 i , r> .. celled breaking off, reproduce the fungus. 



somewhat extensive series 01 experiments it 



was found that potassium sulphide at the rate of half an ounce to a gallon of 

 water, soda hyposulphite at the rate of 1 pound to 10 gallons of water, sulphur 

 powder, formed by slaking lime to which a certain proportion of sulphur had been. 



Fig. 66 CLADOSPOKIUM DENDRITICUM GROWING UNDER 

 MEMBBANE OF APPLE LEAF. 



