360 Mr Line, A Note on the Biology of 



A note on the biology of the ' Croivn-GalV fungus of Lucerne. By 

 J. Line, M.A., Emmanuel College. 



[Read 7 March 1921.] 



' Crown-Gall ' of Lucerne has been investigated and described 

 by several workers since the first report upon it (pubhshed) in 1898 

 by von Lagerheim*. 



The earher accounts merely describe the external appearance 

 of the diseased plants, without giving any details of the fungus 

 causing the disease. More recently (1920) two important papers 

 by Wilsonf, and Jones and Drechsler J, have appeared describing 

 the disease and its causative fungus, Urophlyctis Alfalfae (Lagerh.), 

 P. Magnus, in great detail. 



Before these papers appeared, a detailed investigation of the 

 fungus had been for some time in progress at Cambridge, and was 

 in fact approaching completion at the time of their pubhcation. 

 In view of this it has been thought desirable to pubhsh a brief 

 account of the work, which is in the main confirmatory of the paper 

 by Jones and Drechsler, and hke that, is in considerable disagree- 

 ment with that of Wilson. 



External feaMres of the disease. 



Diseased plants are found to bear wart-hke masses of tissue at 

 about the level of the soil (fig. 1). In advanced cases these may be 

 as much as six inches across, but they are rarely found to extend 

 more than an inch or so below the surface of the ground. 



When these masses are cut across, they show characteristic dark 

 brown areas, the spore cavities in section, among the white tissue 

 composing the gall, giving a marbled appearance. The name 

 'marbled gall' has been suggested to distinguish this type of gall 

 from true bacterial crown-gall. The disease is reported to be fairly 

 common on Lucerne in certain areas west of the Rocky Mountains 

 in the United States ; in this country it has so far been reported from 

 three areas only: in 1906 Salmon§ observed it in Kent; it was re- 

 ported from Bedfordshire by Mr Amos (University Lecturer in 

 Agriculture) in 1917, and was found in two fields near Cambridge 

 in 1919 by the writer. It has again been found in Kent (1920), and 

 in another field, adjoining the first, near Cambridge. It is probable 

 that it is much more common than these reports would suggest, 



* Lagerheim, G. (1898). Bihang K. Svensha Vet. Akad. Handl Bd. 24, Afd 3 

 No- *• t Wilson, 0. T. (1920), Bot. Gaz. v. 70, No. 1. pp. 51-68. 



% Jones, F. R. and Drechsler, C. (1920). Journ. Agric. Re.^. (U.S. A ) vol 20 

 No. 4, p. 295. ' 



§ Salmon, E. S. (1907). Journ. 8.E. Agric. Coll. Wye, No. 16, p. 296. 



