46 Investigation of BhUj Rot of Narcissus 



Summary. 



The bulb rot disease, or ring disease, of Narcissus is due to the 

 attack of an eelworni, Tylenckus devastalrix. These eelworms are of 

 constant occurrence in the diseased bulbs, and the disease can be pro- 

 duced by infecting healthy plants with the eelworm. 



A description is given of the symptoms and course of the disease 

 as it appears in nature, and certain precautionary measures are suggested. 



I have great pleasure in expressing my thanks to Mr J. W. Barr 

 (Messrs Barr and Sons), Mr Hales (Chelsea Physic Gardens), Mr Leake 

 (The Floral Farms, Wisbech), Mr Pearson (Messrs J. R. Pearson and 

 Sons), and Mr J. Walker (Walker Bros.) without whose cordial co- 

 operation and generous help the work could not have been carried 

 out. I am also indebted to Mr J. C. Fryer for help and suggestions 

 with regard to treatment. 



I should also like to take this opportunity of thanking both 

 Professor V. H. Blackman and Professor J. B. Farmer for their stimu- 

 lating and helpful criticism. 



LIST OF PAPERS QUOTED. 



1. Beyerinck, M. W. "De oorzaak van der ki-oefziokt van jongo ajuinplanten." 



Mamulblad (ler Hall. Maatschappij van Landbouw, No. 9, 1883. 



2. Bos, RiTZEMA. "Untersuchungen liber Tyhnchns devasfafrix." Biol. Cevtral- 



blatt, 1887-8. Bd. vii, p. 232. 



3. "L'Angxiillulo do la Tige (Tyhnchns devasfad-ix) et les Maladies des Plantes 



dues a ce Nematode." Haarlem. 3Iusee Teyler Archives, S6r. 2, 1887-1892, 

 p. 161. 



4. Fryer, J. C. Narcissus Flies. Board of Agriculture and Fisheries Leaflet, 



No. 286, 1914. 

 4a. Hewitt, T. R. Eelwonns in Narcissus Bulbs. Joyr. Dept. Agric. and Tech. 

 Insfif., Ireland, xiv, 1914, pp. 345-353. 



5. KuiiN, J. Zeit. d. Landwirthscliajtlichen Centralvereins der Provenz Sachsen, 



1867, p. 99. 

 6. Ueber die Wnrmkrankheit des Boggens imd uber die Uebereiiis'immiing. 



7. DE Mann, J. G. Die freie in der reinen, Erde nnd im Silssemvasser lehenden 



Nematoden der niederlandeschen Fauna, 1884, p. 142. 



8. Marcinoswski, K. " Parasitische und semi-parasitische an Pflanzen lobende 



Nematoden." Arbeiten aus der Kaiserlichen Biologischen Ansfalt f. Land- und 

 Forslwirlschajl. Bd. vii, 1910. 



9. Massee, G. "A disease of Narcissus bulbs." Kew Bidletin, 1913, p. 307. 



10. Prillieux, E. "La Maladie vermiculaire des Jaeinthes." J. de la Soc. Nat, 



d' horticulture, 3"!% s6r. iir, 1881, p. 253. 



