THE BOTRYTIS BLIGHT OF TULIPS 1 



Edwin F. Hopkins 

 THE HOST PLANTS 



It is reasonably certain that the Botrytis blight is restricted to plants 

 in the genus Tulipa. This genus includes Tulipa Gesneriana L., the 

 Darwin, or late, tulips, T. suaveolens Roth., the Due van Thol tulip, 

 embracing the early and forced varieties, and T. sylvestris L., the so- 

 called wild tulip. The members of this genus have been under cultivation 

 for so long that it is difficult to refer them to any natural species although 

 the arrangement just given is commonly accepted (Bailey, 1917 : 3393-3394) . 2 



Numerous references to the occurrence of this disease on other hosts 

 have appeared in the literature. However, most of these statements are 

 based on insufficient evidence, and show that the author had under 

 consideration another Botrytis disease and did not attempt to verify his 

 conclusions by cross inoculations. Ritzema Bos (1903a:20), for instance, 

 s ys that while the disease affects other bulbs, such as hyacinths, gladioli, 

 and certain iris species, the tulip is by far the most susceptible. Klebahn 

 (1905:15-17) takes exception to this statement since he has found the 

 disease on none of these plants except the tulip; furthermore, his experi- 

 ments show the hyacinth to be immune. He seems to infer that Ritzema 

 Bos was confusing two different diseases, and that possibly, on these 

 hosts, the disease with which he was dealing was caused by Sclerotium 

 Tuliparum Klebahn. However, Klebahn states that practical gardeners 

 have told him that on ground which had borne bulbous begonias and 

 dicentra no tulips came up. 



Other notes frequently appear by authors who evidently confuse 

 diseases caused by other species of Botrytis with the one under con- 

 sideration, which is caused by Botrytis Tulipae (Lib.) comb. nov. Halsted 

 (1891:352) gives a good example of this in attributing the disease on 

 onions to this organism. 



1 Also presented to the Faculty of the Graduate School of Cornell University, March, 1920, as a major 

 thesis in partial fulfillment of the requirements for the degree of doctor of philosophy. 



Acknowledgment. The author wishes to express his thanks to Professor H. H. Whetzel, of Cornell 

 University, for his many valuable suggestions and for his helpful advice during the progress of the work. 



2 Dates in parenthesis refer to Bibliography, pages ■!.")!> to 301. 



315 



