EELWORM GALLS 113 



Economic Notes 



It will be apparent from what has been written that 

 the majority of gall-causing eelworms are troublesome 

 pests ; there is, moreover, always the possibility that species 

 now infesting plants of little economic importance may 

 establish themselves upon cultivated ones. / 



Worthington G. Smith recorded in the Gardener's 

 Chronicle, 1886, vol. xxv., p. 41, the presence of little 

 black spherical galls on the leaves of an Odontoglossum, 

 which were caused by an eelworm. 



Miss Ormerod, in 1891, observed galls on Vicia Faha 

 Linn, caused by Tylenchus devastatrix. The stem is short- 

 ened and bears pronounced irregular swellings. 



There are numerous Continental records of galls on mem- 

 bers of the family Liliaceae caused by Tylenchus devastatrix. 

 The evidences of attack are slight in many cases, but there 

 is undoubted hypertrophy and consequent weakening of the 

 plant. 



Heterodera radicicola does much mischief on the Continent 

 amongst cultivated varieties of Clematis and various 

 Rubiaceae (notably Gardenia, Coffea, Ixora, and Hamiltonia), 

 causing nodosities to arise on the roots. 



For detailed particulars concerning the stem eelworm 

 (T. devastatrix) and the Wheat eelworm (T. tritici), the 

 reader should consult the second edition of Miss Ormerod's 

 "Manual of Injurious Insects," and Leaflets 46 and 75 

 issued by the Board of Agriculture. 



