The Gray Bulb- Rot of Tulips 7 



mentions the earlier work of Wakker, but attributes the disease there 

 described to Botrytis tulipae also. It is evident from his description of the 

 symptoms (1903a: 178-181) that he was dealing with bulbs affected with 

 Sclerotium tuliparum, as well as some attacked by Botrytis tulipae. This 

 conclusion is further supported by his observations (1903a: 186-187) on the 

 two types of sclerotia and mycelia which he found in the diseased bulbs. 



Klebahn (1904: 19-21), investigating the diseases of tulips in the gardens 

 in Hamburg in the spring of 1903, described the symptoms of the gray-rot 

 disease and, following the lead of Ritzema Bos, likewise attributed it to 

 Botrytis tulipae, with which he made infection experiments. The large 

 sclerotia which he found in the soil and about the crowns of rotting tulips, 

 and which failed to develop in his cultures of Botrytis tulipae, led him to 

 doubt their identity with the small sclerotia of this species as is shown by 

 the following : " Diese Umstande zeigen allerdings zunachst nur, dass zu 

 der Botrytis iiberhaupt Sklerotien gehoren, aber nicht unbedingt, dass die 

 an den krankeu [sic] Zwiebeln aufgefundenen grossen Sklerotien (Fig. 3) 

 mit der auf den Blattern vorkommenden Botrytis in Zusammenhang 

 stehen." (Klebahn, 1904, figures 1 and 3.) 



Continuing his investigations, Klebahn soon (1905:14-17) came to the 

 conclusion that the large sclerotial fungus with which he was working is 

 distinct from Botrytis tulipae as well as from Sclerotinia bulborum, since 

 he was unable to obtain any conidial or sexual fruiting structures. 

 His later investigations confirmed this conclusion but disclosed nothing- 

 further as to the taxonomic relationships of the fungus. He named it 

 Sclerotium tuliparum (1905:13), apparently being unaware that this name 

 had already been applied by Schlechtendal (Bouche, 1831:223) to the 

 fungus now known as Botrytis tulipae. 



The fungus associated with the rotting tulip bulbs in the beds near the 

 Boyce Thompson Institute corresponds in all respects, both in nature and 

 in pure culture, with the descriptions and illustrations given by Klebahn. 

 Moreover, comparisons of pure cultures with cultures of the fungus 

 received from Holland 5 and England 6 show only such slight cultural 

 differences (Plate III) as are to be attributed to physiological variations of 

 individual strains. There appears, therefore, to be no doubt that we are 

 here dealing with the pathogene now commonly known to European 

 workers as Sclerotium tuliparum Klebahn. 



Taxonomic relationships 



In the course of these investigations, certain distinctive characters 

 in the morpholog}' of the pathogene have been observed which seem to 



f Three strains were isolated from sclerotia on bits of tulip bulbs sent to the senior author by Uitzema 

 Bos in 1915. Another culture from Holland was obtained from the pure-culture laboratory of l)r VVester- 

 dijk at Baarn in 1924. All of these were identified by the senders as Sclerotium tuliparum Klebh. 



s The culture from England isolated by Miss Wakefield from tulips at Kew Gardens was sent to the authors 

 from the Lister Institute, Chelsea Gardens, London; their number, 1497. 



