36 



INVESTIGATION OF BULB ROT OF NARCISSUS i. 

 PART I. THE NATURE OF THE DISEASE. 



By E. J. WELSFORD, F.L.S. 



{From the Department of Plant Physiology and Pathology, Imperial 

 College of Science and Technology, London.) 



(With Five Text-figures.) 



Introduction. 



The date of the first appearance of the disease in this country is 

 somewhat doubtful. Mr J. W. Barr, of Messrs Barr and Sons, states 

 that he first observed it about twelve years ago in some bulbs of 

 Narcissus Horsfieldii imported from Holland. 



Massee(9) found Fusarirnn hulhigenvm (Cooke and Massee) in Nar- 

 cissus plants suffering from bulb rot and ascribed the disease to this 

 cause. As, however, no infection experiments were carried out, and 

 as there seems some evidence that Fusariiim biilhigenum may exist in 

 healthy bulbs, it is clear that the nature of the disease was not settled 

 by Massee's observations. The absence of definite knowledge as to 

 its cause and the increasing ravages of the disease obviously made an 

 investigation very desirable. 



Diseased bulbs were obtained in April, 1915, and a preliminary 

 examination showed them to be infested with various animal pests, 

 chief among which were Rhizoglyphiis echinopus, Eumerus strigatus, 

 Merodon equestris, and Tylenchus devastatrix ; certain scales were also 

 found to contain Fusarium hulbigemnii and bacteria. It was necessary, 

 therefore, to determine which, if any, of the above was the primary 

 cause of the bulb rot. 



^ This investigation wa.s undertaken jointly by the Imperial College of Science and 

 Technology and the Royal Horticultural Society. 



