EXPERIMENT STATION BULLETINS. 347 



FUNGOUS DISEASES OF FRUITS IN MICHIGAN. 



BY n. O. LOXGYEAK. 



[Special Bulletin No. 25.] 



The necessity of systematically combating the diseases which affect the orchard 

 and its product is so generally recognized at the present time by the progressive 

 fruit grower, that it seems scarcely necessary to urge the importance of this 

 matter in his case. In fact the spraying and other treatment of his trees by 

 the professional fruit grower forms a regular part of each season's work, and 

 any information which leads to a clear understanding of the agencies of disease 

 is sure to be appreciated by such a person as enabling its possessor to do this 

 work more intelligently, therefore more successfully. In spite of the vast amount 

 of information along this line which has been published during recent years 

 there is still a considerable lack of knowledge of the true nature of the common 

 diseases to which orchard fruits are subject. Thus the general farmer who grows 

 fruit as one of several products is too often without a proper understanding of 

 these matters, consequently his trees are usually allowed to take care of them- 

 selves. The result is very evident in the diseases which appear. The leaves, 

 the organs of respiration and assimilation, become spotted and unhealthy or 

 perhaps shrivel and fall off; the branches die back; the trunks are scarred, 

 cankered and decayed; and the fruit while dimished in quantity is often of so 

 poor a quality as to seriously injure its market vaule and keeping qualities. The 

 serious losses in the case of barreled apples which were badly affected with scab 

 has led the apple buyers in some portions of the state to refuse the fruit from 

 orchards which have not been properly sprayed and tended. Thus in such in- 

 stances the loss consists not merely in the diminished crop of poor quality but also 

 in the absence of a market for the fruit. 



While a great deal of information relating to plant diseases and their treatment 

 has been printed in bulletins and agricultural papers it is so scattered that the 

 majority of persons engaged in fruit growing in this state doubtless find it 

 somewhat tedious to find this information when wanted on short notice. Con- 

 sequently this bulletin is intended to serve as a sort of text book of the diseases 

 most common and destructive to fruits in Michigan. Technicality has been 

 avoided as much as possible, the attempt being made to give clear and readily 

 comprehended descriptions of each disease together with the most approved 

 methods of treatment. The information has been gathered wherever the most 

 satisfactory accounts of diseases and their treatment could be obtained. The 

 publications of the U. S. Department of Agriculture and the bulletins of the 

 various State Experiment Stations have furnished the greater part of this matter. 

 This bulletin, however, is not a mere compilation. Most of the figures are from 

 original dawings and photographs and represent actual specimens studied by the 

 author. Also personal observations of the principal diseases and the more 

 common methods of treatment have been made. 



COilMOX CAUSES OF PLA>-T DISEASES. 



Plants may be diseased in several ways. In fact the condition brought about 

 by anything which disturbs or prevents the carrying on of the normal functions 

 of a plant or any of its organs may, in a general way, be considered a disease. 

 The most common diseases of plants are now known to be due to the attacks 

 of parasitic organisms such as bacteria and fungi. Fungi, however, constitute 

 the commonest of the causes of diseased conditions in plants. 



Fungi themselves are plants of a very low order and are quite simple in 

 structure as compared with plants which bear leaves and flowers. Most of the 

 flowering plants possess leaves which contain a green coloring matter 



