344 



Kansas State Board of Agriculture. 



FIG. 289. Alfalfa leaf spot (Pleosphcerulina briosiana Pollacci), magnified. 



The same treatment recommended for the other alfalfa leaf spots ap- 

 plies here. 



DOWNY MILDEW OF ALFALFA (Pernospora trifoliorum De. By.). This 

 disease was present in 1914 and again in increased quantities in the first 

 crop of 1915. It is especially noticeable on the young alfalfa plants, but 

 it does not confine its attack to one-year-old plants. The first crop ap- 

 pears to be the only one atacked in Kansas, and up to the present no 

 particular damage has resulted except in a slight loss in yield in the first 

 crop. Warm, damp weather in May is especially favorable for its de- 

 velopment and spread. 



The uppermost leaves seem to show the disease first; they turn a pale 

 green or slightly yellowish color. If such leaves are examined on the 

 under side they will show a very fine mold-like growth, slightly grayish 

 in color. (See Figs. 290 and 291.) This is the fungus causing the dis- 

 ease. It sometimes happens that the entire tips of the shoots become 

 affected with this fungus. (See Fig. 292.) In such case the plant is 

 stunted, and the affected shoots will cease further growth. 



Generally speaking, this disease is not serious enough to warrant 

 early cutting to prevent loss. 



RED OR VIOLET ROOT ROT OF ALFALFA (Rhizoctonia violacese Tul.). 

 The records on hand seem to indicate that this disease is increasing in 

 this state. It was first reported in Kansas seventeen years ago. The 



