COLLETOTRICHUM DISEASE OF AGAVES 



155 



masses of conidia; setae acute to blunt, light brown, 3- to 5-septate, 110 

 to 170 MX 5 to 6 Pi conidia oblong to cylindrical, hyaline, with one to 

 two gnttules,16to31^X5to6/,; conidiophores erect, hyaline, usually 

 simple, 6 to 7 fi in diameter, bnt very variable in length in different acer- 

 vuli. No ascigerous stage was found. 



Habitat: On the leaves of Agave Americana, A. atro- 

 virens. A. horrida, A. marmorata, A. potatorum, A. Utah- 



often causing the death of younger 



A. spp 



plants. 



A. Utah 



diseased, and it is thought that the fungus was introduced 

 into the greenhouse with this species. After a short time 

 the disease spread to other species, none of which suffered 

 so much as the original host. 



A search for the fungus on agaves in the Southwestern 

 United States has thus far failed to locate the .disease, 

 either on wild or cultivated plants. In the herbarium of 

 the Missouri Botanical Garden, however, there are speci- 

 mens named Gloeosporium macropus Sacc, which devel- 

 oped during a fortnight's detention in the collecting box of 

 mature leaves of an undescribed large-leaved Agave of *»■- 

 Americanae group collected at La Barca, Mexico, 



Some of the zoi 



by 



Dr. Trelease in the summer of 1901. 



acervuli of these specimens show the characteristic setae 



of Colletotrichum, while their other characters agree with 



Ag 



Mr 



cessful in checking the spread of the disease, which it 

 a K,r ™™ a t nnnHit.ions. He places all of the dis 



fav- 



plants in a separate locality, and removes the lower leaves 



become 



pread 



In case of older 

 Young 



often die in spite of the removal of the leaves, the fungus 

 apparently penetrating the whole plant. Bordeaux mixture 

 of the ordinary formulae is beneficial in preventing the 

 spread of the fungus to adjacent plants. 





