AN APPLE ORCHARD SURVEY OF WAYNE COUNTY, NEW YORK. 335 



THE APPLE-SCAB FUNGUS (Venturia inaequalis). 



Importance of this disease. The worst disease with which the apple- 

 grower has to contend is the apple-scab, commonly called " the 

 fungus." More questions are asked about it than about any other 

 enemy of the apple, and there is great difference of opinion among 

 farmers as to what it is and what to do about it. True, spraying has 

 become an accepted practice and the best fruit-growers practically 

 eliminate the scab, but the majority of farmers do not do so. The 

 varying opinions are due to the fact that the fungus is invisible or 

 inconspicuous until it " goes to seed." A knowledge of its life history 

 is essential to any intelligent treatment of it. It has been frequently 

 described, but the information is 

 not yet sufficiently disseminated. 

 I shall, therefore, attempt to answer 

 some of the common questions that 

 are asked about it. A few ques- 

 tions are asked over and over again. 

 "What is the fungus?" "What 

 causes it ? " " Why is it worse in 

 wet seasons?" "Why are some 

 varieties more affected than others?" 



What is the scab fungus? "This 

 apple-scab is no new pest. It has 

 no doubt been seriously present FlG 7 &_ Young appies severe i y attacked 

 ever since apples were grown in by the scab fungus. 



the country, causing many fail- 

 ures of crops which were laid to the weather or the moon."* 



This fungus is a very small plant that grows as a parasite on the 

 leaves and on the apple, the apple is its soil. We might say that it 

 is a weed that grows on the apple and allied fruits rather than on the 

 ground. It lives over winter on the fallen leaves and perhaps to a very 

 limited extent on the branches. " Scab makes its first appearance early 

 in the spring, usually soon after the leaves begin to unfold, and it is 

 while these and the fruit are in a young condition that the fungus 

 can best infect them."f (See Fig. 78.) The seed (spore) falls on the 



*L. H. Bailey in Cornell Bulletin 84, Jan., 1895. 



fGeorge P. Clinton, Bui. 67, Univ. of 111. Agr. Exp. Sta. Dec., 1901. 



