62 Report of the Botanist of the 



die. The diseased stems are covered with the pycnidia of a 

 fungus belonging to the genus Phoma, and it has been shown by 

 inoculation experiments that this Phoma is the cause of the dis- 

 ease. Although no experiments have been made it is probable 

 that stem rot may be prevented by spraying with Bordeaux mix- 

 ture as for anthracnose. 



THE ANTHRACNOSE. 



Early in the spring of 1S97 the writer's attention was called to 

 an anthracnose which was doing serious damage to a bench of 

 Antirrhinum majus in a greenhouse on Long Island. Upon in- 

 quiry' among florists it was learned that the anthracnose is a 

 common disease, and wherever it occurs is more destructive than 

 any other disease to which the Antirrhinum is subject, sometimes 

 completely ruining an entire crop. 



It attacks the plants at any stage of their growth, both in the 

 greenhouse and in the field. In the greenhouse it is more de- 

 structive in the fall and spring than during the winter. In the 

 field its ravages are most conspicuous in August and September. 



On the stems it produces numerous elliptical sunken spots from 

 three to ten millimeters in length; and on the leaves circular dead 

 spots having a diameter of from three to five millimeters. These 

 spots are caused by an undescribed species of Colletotriclium for 

 which we here propose the name Colletotriclium antirrhini? 



ON the stems. 

 Stems of all ages are attacked: The coalescence of several 

 large spots may girdle the plant at the base; a single large spot 



^CoUetotrichvm a7ithThini n. sp. Producing depressed spots on stems 

 and leaves of Antirrhinum mnjus L.; stem spots elliptical, often confluent, 

 3-10 mm. long; leaf spots orbicular, 3-5 mm. in diameter. Acervuli numer- 

 ous and crowded, particularly on the stem spots; amphigenous on the 

 leaf spots. Stroma well developed; on the leaves only slightly colored, 

 but on the stems dark brown. Seta? abundant, especially on the stems, 

 dai'k brown, 50-100 />- long, unbranched. mostly straight, tapering uni- 

 formly to a sub-acute point. Conidia 16-21 x 4 IJ- straight or slightly 

 curved, with rounded ends or frequently obtusely pointed at one side of 

 one end, granular with a vacuole at the center when young. Basidia short 



