EXPERIMENT STATION BULLETINS. 



351 



Fig. 3. — Microscopic structure of the scab fungus. A, portion of a section through a scab spot on an 

 apple showing tlie fungus; (b), spreading under and lilting the cuticle, a; c, partly disorganized cells 

 of the apple; e, healthy cells of the apple; B, two spore-bearing stalks (conldiophores), giving rise 

 to summer spores (conidia), f; C, spores germinating; D, portion of a section through an affected 

 leaf of apple which has lain on the ground over winter, and has given rise to the winter stage spore 

 of the disease; g. spore case, (perithecium), contaming a bundle of spore sacs (asci); E, two spore 

 sacs (asci), more highly magnified, each containing eight two-celled winter spores, three of which are 

 shown at F. Ail highly magnified. (Original.) 



The planting of varieties which are naturally less subject to the scab is also 

 to be considered as a preventive measure. Spraying for the prevention and 

 treatment of this disease has proven of unquestioned value and a paying invest- 

 ment to the apple grower. The first application made before the buds open may 

 be the copper sulphate solution (A) which is cheaper and easier to prepare and 

 use than Bordeaux mixture. By many growers this application is considered the 

 most important one for fungous diseases and should not be neglected. At this 

 time great care should be used, to avoid driving on the soil when full of water, 

 especially if it contains much clay as it is apt to become puddled thereby and its 

 texture much injured. After the leaves appear, however, it will be necessary to 



