458 



DISEASES OF ECONOMIC PLANTS 



somewhat elongated in the direction of the longitudinal 



axis of the leaf (Fig. 197). When at the node, the disease 



^ usually involves the bases of both of the 



A leaves, as well as the stem between them. 



^ As these nodal spots age, the disease pene- 



B trates through the stem, killing its tissue, 



^B which shrinks somewhat and becomes soft 



^B and disintegrated, resulting in the death of 



^^ the more distal portions of the plant. 



^B A striking feature is the tendency of this 



^H disease to infect to a large degree one variety, 



^B the Mrs. Thomas W. Lawson, to the exemp- 



^^ tion of others. 



^H Fusariose, of stems, stem rot, wilt, die back 



^^H {Fusarium sp.). — Described in 1897 by Ster- 

 ^H gis, this rot occurs chiefly upon the stems ^ 

 ^H and larger branches, discoloring the wood and 

 ^H killing the bark, but rarely causing soft rot. 

 mM The diseased plants die gradually with yellow- 

 ^B ing and drying of the foliage, much as though 

 ^B due to insufficient water supply. 

 J^ When practicable, beds should be disin- 



fected and new uninfected stock introduced. 

 The disease when first introduced upon a 

 few plants can be stopped by the immediate 

 removal and destruction by fire of the dis- 

 eased plants. 



Fusariose, of leaves, leaf spot {Fusarium sp.). — This is 

 a secondary disease following primary lesions of the rust. 

 The spots as described by Stewart ^ vary from 3-25 mm. in 



1 Stewart, F. C, Bot. Gaz. 27, 129, February, 1899. 



2 Stewart, F. C, N.Y. (Geneva) Agr. Exp. Sta. Bui. 164, 1899. 



Fig. 197. — 

 Carnation leaf 

 showing spot 

 caused by Al- 

 ternaria Dian- 

 thi. Original. 



