Damping Off. 343 



Damping Off by Yakious Fungi. 



Several fungi, probably quite a large number, produce phases of 

 damping off at certain times, while their evil effects are not con- 

 fined to this peculiar class of injuries. Pliytophthora cactorum 

 (L. et C.) Schroeter {Phytophthora omnivora de Bary) was first 

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

 houses. This fungus frequently destroys seedlings of trees, causing 

 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. Colletotrichuin lindemuthianum on bean seedHngs is a 

 good illustration of this, as Ralsted '^ has already shown. The same 

 author points out that a ColletotricMom on cuttings of albutilon, 

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

 some houses ruins the bulk of the cuttings in the bed, while a 

 Gloeosjporium damp off rose cuttings. 



Another anthracnose, Colletotrichuin gossypii Southworth some- 

 times damps off seedling plants of cotton. Carnations are also 

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



Halstead found a Phyllosticta in one case and in another case 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 Halstead 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, probably 

 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 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. 



29 4th Kept. N. Jr. Agr. Coll. Exp. Sta. 291, 1891. 



