COLLETOTRICHUM. 



487 



appear on the leaves, and depressions on the stem, sometimes 



extending so far round that the whole shoot dries up. The 



conidial patches are very much the same on the different hosts, 



and consist of short conidiophores from 



which oval, unicellular, hyaline conidia 



are abjointed. 



C. lycopersici Chest, is the cause of 



a spot-disease on the fruit of tomato in 



the United States. 



C. spinaciae Ell. et. Hals, causes a 



destructive disease on cultivated spinach. 

 ,0. malvarum Br. et Gasp. (C. althaeae 



Southw.^) produces a disease of cultivated 



hollyhock. It is most injurious to the 

 seedling plants, and has caused great 

 loss in America and Sweden. The fungus 

 may attack any organ, and produces spots 

 which enlarge so rapidly that death of the 

 host may result. 



0. gossypii Southw.^ Anthracnose of 

 Cotton. This disease, although it may 

 be found on stems and leaves, is most 

 frequent and most conspicuous on the 

 fruits or " bolls " of the cotton-plant. 

 The first signs are tiny depressed spots 

 of a reddish-brown colour, and as these 

 enlarge they cause blackening of neigh- 

 bouring tissue. When the spores are developed the spots 

 become dirty grey, or perhaps pinkish if the spores are present 

 in large numbers. Fruit attacked in this w&j does not mature 

 well, and the yield of cotton is greatly prejudiced. Atkinson 

 found the cotyledons easy to infect with the disease. The 

 spores are oblong and tapering, with a shallow constriction in 

 the middle ; they are borne either on short colourless basidia 

 or on long, olive-coloured, septate setae, both kinds of conidio- 

 phore being produced in acervuli or patches. 



C. adustum Ell. is the cause of a leaf-spot on orange in Florida. 



Fig. 29S.—C'oUetotHchum Linde- 

 muthianuTm. on pod of Kidney 

 Bean. Enlarged pustule and 

 conidia. 



^South-worth, "A New Hollyhock Disease," Journal of Mycology, vi., 1890. 

 ^Southworth, Journal of Mycology, vi., 1890, p. 100. 

 Atkinson, Alabama Agric. Exper. Station Bulletin, No. 41, 1892. 



