230 



Anthracnose 

 Caused by Gloeosporium ampelophagum (Pass.) Sacc. 



Anthracnose, a disease of lesser importance on grapes in Illinois, at- 

 tacks all green parts of the vine, but especially the young shoots, berries. 

 leaf stalks, and berry stems. On shoots and other stem parts it causes 

 small reddish brown, somewhat sunken spots, which enlarge to an oval, 

 with a gray and noticeably sunken center. Spots on berries first appear 

 round and dark brown, but are later surrounded by a bright red ring, 

 giving them a marked bird's-eye appearance. The attacked berries even- 

 tually rot. 



Anthracnose has probably been present in Illinois ever since grapes 

 have been grown in the state. Evidently, however, it has been confused 

 with black rot, so that early reports found in the Transactions of the 

 State Horticultural Society are not definite enough to be dependable. 



The present known occurrence of anthracnose is shown on Map 82. 

 Of the 18 counties in which it is known to occur all but threp lie in the 

 northern half of the state. The relatively unimportant nature of this 

 disease to the commercial producer is apparent from the fact that, with 

 the exception of the grape regions in Madison, Sangamon, and La Salle 

 counties, anthracnose has not been found in the important grape-growing 

 centers. Its known range in the state appears, from our present infor- 

 mation, to be strikingly northern. 



A partial explanation of the absence of anthracnose from commercial 

 regions is to be found in the fact that the Concord grape, so commonly 

 grown in Illinois, appears to be markedly resistant. 



Where special effort is necessary to control this disease, the usual 

 program of summer spraying, supplemented by a dormant spray ( lime- 

 sulfur, 1-8), will be found satisfactory. 



Powdery Mildew 

 Caused by Uncinula necator (Schw.) Burr. 



Powdery mildew, like the downy mildew, is chiefly a leaf disease, but 

 differs in that it is caused by a fungus which is almost entirely super- 

 ficial. All young parts of the vine are subject to attack. Whitish, 

 powdery spots appear on the leaves. As the spots grow larger they cause 

 a stunting of young leaves, and older leaves curl upward and eventually 

 die. Mildewed blossoms fail to set fruit, and diseased berries either shell 

 of? or are badly deformed or cracked. 



It is thought that powdery mildew shares with the downy mildew 

 the place of second importance among grape diseases in Illinois, but ob- 

 servation on distribution and severity are not yet sufficient to show its 

 relative importance clearly,. 



The earliest definite record of this disease is a collection niade at 

 Cobden, Union countv, in 1881. Anderson collected it at Urbana, Cham- 



