4 H. H. Whetzel and John M. Arthur 



(1903a: 190) that Wakker also had only the Botrytis blight under con- 

 sideration when he described his " tulpenziekte." 



Because of the failure of tulips to come up in the spring in soil-infested 

 areas, the disease is called by the Dutch growers " wegblijven " (away 

 remaining) and the contaminated areas " kwade plekken " (bad spots) 

 or " kwade grond " (bad ground). From the fact that Wakker does not 

 use these terms in his early description of the disease, Ritzema Bos (1903 a: 

 191) concludes that the disease is new to Dutch bulb-growers in spite of 

 the assurance of growers in Noordwijk that it had been known to them for 

 more than twenty years. 



Klebahn (1904:18) observed the disease in the spring of 1903 in the 

 botanical gardens at Hamburg, Germany, and began a series of investiga- 

 tions culminating in three papers (1905, 1906, and 1907), the most impor- 

 tant contributions on the subject to date. In his early work (1904) he 

 too confused the gray bulb-rot with the Botrytis blight, but he soon dis- 

 covered that he was working with two distinct diseases. In his later papers 

 he clearly distinguished the gray bulb-rot from the Botrytis blight, giving 

 it the name sclerotium disease (1905: 1-18). 



As none of the names thus far applied to the disease appear to be entirely 

 satisfactory, the term gray bulb-rot is proposed as indicating more definitely 

 its character. 



RANGE AND IMPORTANCE 



The gray bulb-rot, which seems to have first appeared in Holland in the 

 early eighties, has gradually become widespread and destructive in 

 certain sections of the bulb-growing districts there. That it was of rela- 

 tively little importance in 1884 seems evident from the meager considera- 

 tion given it by Wakker (1885), who, however, reports it as sometimes de- 

 st roving most of the tulips in a bed. Ritzema Bos (1894:229) reports what 

 was undoubtedly this disease as having been very destructive in scattered 

 localities in the bulb districts during the seasons of 1892 and 1893, and again 

 (1895 : 348) in 1894. In his report ten years later on the investigation begun 

 at that time, he intimates (1903 a: 177-178) that the disease had in the 

 meantime become much more general and serious in the bulb districts, and 

 that it was even then becoming a factor in the export trade in bulbs to 

 adjacent countries, because of losses to gardeners in Germany and elsewhere 

 who purchase the bulbs for forcing and outdoor plantings. Since, how- 

 ever, he constantly confused the bulb-rot with the Botrytis blight, one 

 cannot estimate from his reports the relative importance of the two diseases. 



Klebahn (1905:13-14) concluded from his early inoculation experiments 

 that the bulb-rot was far more dangerous and serious than the Botrytis 

 blight, but from observations made shortly afterwards on a visit to the 

 bulb-growing districts of Holland he observed (1907:3) that the Botrytis 

 blight was not so harmless as he had been led to believe, that it was much 

 more widespread than the bulb-rot, and that it caused the growers much 





