420 VIOLET ROOT-FUNGUS. GRASS MILDEW. 



Red clover is also often marked in the snnimer and full by 

 similar but darker brown spots, bearing in the center of each a 

 brown cup, scarcely 1.32 in. in diameter, that opens irregularly 

 at the top and so allows the escape of its spores. This is Phacid- 

 iuiii (or Pseudopeziza) trifolii, which at times does considerable 

 damage in Europe. 



9. Violet root-fungus, {Leptosphmna circinnns, Fckl.). 

 Forming a violet mold on the roots of alfalfa, red clover, etc., 

 which soon rot, the parts above ground turning yellow and 

 dying. 



In Europe, Lucerne is subject to a disease that manifests itself 

 by the appearance of yellow spots in the fields. These spread 

 until the entire crop is often affected. The trouble lies in a 

 violet-colored mold that develops on the roots of the plants, 

 spreading from one to another through the soil, and finally pro- 

 ducing spores by which it is apparently carried over the winter. 

 This disease has not been recognized yet in the United States, 

 but what is held to be a state of the root fungus — a cobwebby, 

 white mycelium, known as the snow-mold, that covers the 

 ground, leaves, etc., just as the snow disappears in early spring 

 — has been noticed in groat abundance at River Falls, Wis., by 

 my friend, Professor King, so that it is not improbable that the 

 parasitic form will soon be found. No remedies for it have been 

 proposed, except digging ditches, as deep as the roots extend, 

 about diseased parts of the field when it first appears to prevent 

 it from spreading. 



10. Grass-mildew, {Erysiphe graminu, D. C). Forming a 

 pure white, cobwebby or mealy coating on the upper side of the 

 leaves of grasses, especially in the shade. 



The German equivalent (meal-dew) of our common name for 

 the group of fungi to which this species belongs is expressive of 

 the appearance presented by them in their early stages, when 

 they cover the surface of the plants they grow on with a tine. 



