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 

 leaves, as well as the stem between them. 

 As these nodal spots age, the disease pene- 

 trates through the stem, killing its tissue, 

 which shrinks somewhat and becomes soft 

 and disintegrated, resulting in the death of 

 the more distal portions of the plant. 



A striking feature is the tendency of this 

 disease to infect to a large degree one variety, 

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

 tion of others. 



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

 (Fusarium sp.). — Described in 1897 by Ster- 

 gis, this rot occurs chiefly upon the stems' 

 and larger branches, discoloring the wood and 

 killing the bark, but rarely causing soft rot. 

 The diseased plants die gradually with yellow- 

 ing and drying of the fohage, much as though 

 due to insufiicient water supply. 



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 3-25Tnm. in 



' Stewart, F. C, Bot. Gaz. B7, 129, February, 1899. 



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



Fig. 197. — 

 Carnation leaf 

 showing spot 

 caused hy Al- 

 temaria Dian- 

 thi. Original. 



