DAMPING OFF. 269 



(L,. et C.) Schroeter {Phytophthora omnivora deBary) was first 

 discovered as the cause of decay of species of cactus in forcing 

 houses. This fungus frequently destroys seedlings of trees, caus- 

 ing them to become brown and later to decay. 



Several of the anthracnoses are known to produce genuine 

 cases of damping off while their injury is by no means confined 

 to this trouble. Colletotrichum lindemuthianum on bean seedlings 

 is a good illustration of this, as Halsted 29 has already shown. The 

 same author points out that a Colletotrichum on cuttings of albut- 

 ilon, passiflora, clematis and jessamine causes them to damp off 

 and in some houses ruins the bulk of the cuttings in the bed, 

 while a Gloeosporium damps off rose cuttings. 



Another anthracnose, Colletotrichum gossypii Southworth some- 

 times damps off seedling plants of cotton. Carnations are also 

 affected in the same way by Volutella dianthae (Hals). 



Halsted found a Phyllosticta in one case and in another case a 

 a Septoria growing in the stems of decaying chrysanthemums, and 

 while this was the only fungus present it was not certainly deter- 

 mined as the cause of the trouble. According to Halsted bacteria 

 also cause seedlings of cucumbers to damp off. 



A species of Botrytis which is very common in forcing houses 

 producing a variety of diseases of various plants frequently damps 

 off leaves and twigs of cuttings or well rooted plants. When the 

 houses are quite damp the fungus gains hold on the plant, prob- 

 ably in the axil of the leaf or branch, because the water is held 

 at these points for a longer time, and once well seated in the 

 tissue continues its work until the leaf or branch is rotted off. 

 Leaves of begonias and branches of roses have been so damped off 

 in the horticultural houses at Cornell University. 



A careful inquiry would probably reveal a large number of fungi 

 which at times produce diseases almost if not quite identical with 

 damping off so far as external appearance goes. 



TREATMENT. 



In the treatment of this trouble especial attention must be given 

 to the environment of the plants and those conditions which favor 

 the rapid development of the parasites. These conditions are 



Rept. N. Jr. Agr. Coll. Bxp. Sta. 291, 1891. 



