Chrysanthemum Diseases 241 



Ray Blight 



Caused by Ascochyta chrysanthemi Stevens. 



Symptoms. This disease attacks the buds or the 

 opened blossoms. The affected blossom becomes 

 brownish, straw colored, and withers. The discolor- 

 ation nearly always begins at the base and works 

 up to the tip of the blossom. Affected buds fail 

 to open altogether. On opened flowers, the disease 

 attacks on one side so that the rays in that direction 

 will become destroyed (fig. 50, b.). The receptacle 

 and the peduncle of diseased blossoms turn black and 

 become shriveled. Portions of the stem may also 

 be attacked, turn black and girdled. 



The Organism. Ascochyta chrysanthemi was first 

 described by Stevens.* The pycnidia are few, oc- 

 cur singly or scattered about, and open by means of 

 a short central ostiole. The spores are oblong, 

 straight or irregular, hyaline, one septate, the ends 

 obtuse or acute. 



Control. All diseased material should be de- 

 stroyed by fire. Careful and frequent spraying will 

 control the disease. 



Septoria Leaf Spot 



Caused by Septoria chrysanthemi Cav., and S. 

 chrysanthemella (Cav.) Sacc. 



Symptoms. This disease usually appears as small 



'Stevens, F. L., Bot Gaz. 44: 241-258, 1907, 



