Minnesota Plant Diseases. 367 



phur to such varieties as are subject to tiiis disease, at intervals 

 during the season, will also be of value, especially on grapes 

 grown under glass. In dry seasons the frequent stirring of the 

 soil will aid in keeping the vines healthy, but upon the first ap- 

 pearance recourse should be had to one of the above fungicides.'' 

 (Mich. Ex. Sta. Bull. No. 121.) 



The burning of the fallen leaves of infected plants is also to 

 be recommended. 



Anthracnose of vines {Sphaceloma atnpelinmn DeBary). 

 This is also known as birds'-eye rot. The cause of the disease 

 is an imperfect fungus and causes great damage in many states 

 of the Union. The extent of its work in Minnesota is not yet 

 known. All parts of the plant are attacked and the disease is a 

 difficult one to combat. The fungus causes small black spots, 

 which later become whitish, though the edge is margined with 

 purple. The spots in the stem sink, leaving depressed regions, 

 while in the leaves dark-brown spots are produced, from which 

 the tissue sometimes falls as in the shot-hole fungus of plums. 

 On the fruit circular spots are produced with a black margin, 

 outside of a red ring, from which the fungus derives its name 

 of birds'-eye rot. The spots may be numerous on a berry and 

 eventually become scabby. An infected cluster of berries bears 

 usually few or no sound ones. The berries die and shrivel but 

 remain attached to the vine. The spores of the fungus are borne 

 in small, black spots, which appear on the leaf and fruit spots. 

 The spore-bearing threads are packed into a cushion which is 

 dark-colored. -From' the surface of this cushion arise the upright 

 thread branches, bearing colorless spores. 



The treatment for black rot of grape is usually recommended 

 for the anthracnose. All diseased portions should be removed. 

 In addition to this, a winter treatment is given in Europe, where 

 the disease was first known and where it has caused a great dam- 

 age. In the old world this disease has been brought under con- 

 trol by winter and summer spraying and the destruction of in- 

 fected parts. "In Europe it is the custom to wash the vines and 

 .stakes during winter or early spring with sulphuric acid and sul- 

 phate of iron solution. The liquid is applied by means of swabs 

 or brushes. It blackens the canes and this is a test of the thor- 

 oughness of the work." (See chapter on fungicides. Iron sul- 

 phate solution.) 



