The Gray Bulb-Rot of Tulips 5 



trouble. There is, however, little doubt that the bull)- rot is a serious 

 disease in regions where it is well established (Klebahn. 1907:12-13). 



The disease has been reported from Switzerland (Miiller-Thurgau, 

 1908:750, and Lendner, 1911), and also by Jaczewski from Russia (Dia- 

 konoff, 1913:281). Although no reference to the disease in England has 

 been found in the literature, 3 it undoubtedly occurs there; to what extent, 

 however, is not known. The senior author received a culture of the 

 pathogene isolated by Miss Wakefield from tulip bulbs in Kew Gardens 

 in 1922. It is remarkable that it has not previously appeared in America, 

 or, if it has, that it has not sooner attracted attention. With the growing 

 restrictions on the importation of Dutch bulbs, and the possibility that 

 Americans must eventually depend more and more on home-grown stock, 

 the appearance of the disease in this country assumes a more than 

 scientific interest. 



The bulb- rot is of greatest economic importance in those districts 

 where bulbs are grown for sale and export, as in Holland. Even there 

 it appears to be confined to certain districts (Klebahn, 1907: 12-13). Since 

 the pathogene appears to be transported but rarely on bulbs in commerce 

 and is apparently not disseminated by spores, it is only occasionally de- 

 structive in tulip beds grown for blossoms, and its ravages are therefore 

 largely confined to the beds that became contaminated by the original 

 importation. Klebahn (1904:21-22), reports, as a result of a survey of the 

 tulip plantings about Hamburg, that the disease is rarely met with, and 

 ther only in an occasional planting of bulbs for flowers. The fields of the 

 one grower near Hamburg who produced bulbs for the trade were free 

 from the disease. Klebahn reports a few isolated cases of the disease in 

 tulips imported from Holland into other parts of Germany (1907:4). 



The gray rot appears, therefore, to be a disease of relatively little 

 danger to tulip-growing in America, where flower production is at present 

 the chief object, even though the bulbs continue to be imported from bulb- 

 growing countries such as Holland, where the pathogene is well established. 

 Should a tulip-bulb-growing industry develop in the United States, the 

 infrequent t ransportation of the pathogene on bulbs, the slowness with which 

 it spreads from bed to bed, and the ease with which contaminated soil 

 may be disinfected, does not warrant any particular concern as to the con- 

 tinued importation of Dutch bulbs into this country. 



SYMPTOMATOLOGY 



The first evidences of the disease are the bare spots in the tulip beds in 

 the spring, where the plants fail to come up. Nearly all bulbs in the soil- 

 contaminated area are usually so injured that they fail to grow. When 



'The reference t'> this disease by Bewley in his book Diseases of Greenhouse Plants (1923:71) is an error. 

 II.- hus mistaken :i Botrytis disease 'not caused by li. tulipae) for the sclerotium disease, as indicated by 

 cultures oi his fungus which lie sent to the senior author. His citation of the article by Ramsbottom is 

 also an error, for that deals only with the nematode of hyacinths. 



