316 Edwin F. Hopkins 



In order to gain some knowledge of the host range of the parasite 

 concerned, numerous cross-inoculations were made by the writer. These 

 experiments, which are summarized under the heading Pathogenicity 

 (page 339), prove that the organism concerned does not attack certain 

 of these hosts under artificial conditions, and therefore it probably would 

 not under natural ones. Klebahn (1904, 1905, 1907) had previously 

 made certain cross-inoculations tending to disprove the existence of a 

 generalized type of parasitism in this pathogene. 



The disease is restricted, under normal conditions, to the genus Tulipa; 

 and while similar Botrytis diseases occur on the other hosts mentioned , 

 and even on the tulip itself, they are not identical with this one. 



VARIETAL SUSCEPTIBILITY 



Varieties of both the early tulips, Tulipa suaveolens, and the late tulips, 

 T. Gesneriana, are susceptible. Likewise, as already mentioned, the wild 

 tulip, T. sylvestris, has been proved susceptible. The writer has collected 

 diseased specimens of many varieties of the first two species and has seen 

 the disease on the wild species. 



Klebahn (1905:11), in his experiments, tested five varieties of tulips, 

 presumably early varieties, but finding all susceptible he drew no general 

 conclusion from this result. He thinks it would be desirable to compare 

 the susceptibility of the early and the late species. 



The writer found the disease on a large number of varieties of both 

 species, and isolated the causal organism; he also succeeded in artificially 

 infecting both species. He had almost concluded that there was not much 

 difference in susceptibility. But in the spring of 1917, in a garden on 

 the Cornell University campus where there was then a severe outbreak 

 of the disease, one variety of late tulips (Baronne de la Tonnaye), which 

 had certainly been exposed to the infection, showed no evidence of the 

 disease. Up to the present time there has not been an opportunity to 

 test this variety further. 



THE DISEASE 



NAMES 



Various names have been applied to the disease. Ritzema Bos (1903 a: 

 19) incorrectly used the name kwaden plekken, a term applied by Dutch 

 bulb growers to soil that will not produce tulips. Later Klebahn (1907:3) 



