Thk Canadian Horticulturist. 



97 



THK AIMMJ-: SCAH. 



R015ABL\ nothing has acted more powerfully in overcoming the 

 prejudice of the f;irmer against agricultural education, than the 

 specific aid to the successful pursuit of his work, which has been 

 given by the chemist, the botanist and the etomologist. Just 

 now fruit growers are under special obligation to the student of 

 microscopic botany, called a mycologist, for the useful results of 

 his investigations into the life history of such fungi as black knot 

 pear blight, apple scab, and a host of others. 

 This latter has been known to l)otanists on the continent of Europe for some 

 fifty years, but, since the year 1869, its habits have been more carefully observec 

 by mycologists, who have named it Fusicladium deiidriticum. We gave some space 

 to its description in \'olume X, page 103, and since that time have endeavored 

 to keep apple growers posted concerning the progress of the evil and the success 

 of the various remedies proposed for its destruction. At that time it had reached 

 Australia ; now we have reports of its presence even in New Zealand. 



An important step in advance was made when it was shown that the funo-us 

 causing the leaf blight of apple, and resulting from its early dropping from the 

 tree, was identical with that known as the scab on the fruit itself. 



On the leaves, the .scab appears first --r--— -"^^ -^.^^ 



as small olive-green spots, of a definite ^r^-*"^ . ^^"">^Siit^>. "V. 

 and rounded outline (Fig. 29). These 

 increase in size, and assume a velvety 

 appearance, with a less regular border ; 

 sometimes two or more spots will coa- 

 lesce, as it were, forming one large and Fig. 29. 

 irregular one. Sometimes even the petioles and the young twigs become 

 afifected : thus in every possible way the fungus tries to rob the tree of its vigor. 

 The most favorable conditions for its growth are the cool, moist weather of 

 spring and fall, while its spread is retarded by the drouth and heat of mid- 

 summer. Owing to the dry, warm weather prevailing in the early part of last 

 summer, our ai)ples were much freer from scab than usual. 



The fungus appears to retain its vitality during the winter season, being 

 known to spread even in barrels from apple to apple ; and it remains in a living 

 condition through the winter on the twigs of the apples, ready to begin its work 

 of devastation in spring-time. The loss caused to the country is alarming. The 

 Secretary of the Illinois State Horticultural Society places the annual loss due to 

 this parasitic growth at $400,000, but this is very small compared with the 

 annual loss to apple growers in Ontario. 



