The Gray Bulb-Rot of Tulips 



13 



Figure 4. " tulpenstecker" used by the dutch bulb-growers for removing diseased 

 tulips with adjacent contaminated soil from the beds 

 (From Klebahn, 1907:30) 



The carbolineum was applied at the rate of from 40 to 50 liters to an 

 " are " (= 120 square yards), being first mixed with sand which was then 

 applied and worked into the upper layer of soil. When bulbs were 

 planted immediately after treatment of the soil, rather severe injury resulted 

 especially where the larger amount of carbolineum was applied. Where 

 the treated soil was allowed to lie idle until the next season, no injury 

 resulted, and excellent, though not perfect, control was obtained. Ritzema 

 Bos suggested that treatment of contaminated soil early in the summer, 

 allowing it to lie idle until autumn, and then planting to healthy bulbs, 

 would largely obviate injury from the carbolineum. Klebahn (1906:562) 

 says that in spite of the work of Ritzema Bos and that of a special commis- 

 sion maintained by the bulb growers of Noordwijk, Holland, no wholly 

 satisfactory method of control had at that time been developed. This 

 is, in his opinion, due largely to their confusing this disease with the 

 Botrytis blight. 



Klebahn (1907:32) recommends a combination of the carbolineum dis- 

 infection with the removal of diseased bulbs. The few diseased bulbs 

 that appear after soil disinfection can be easily removed early in the 

 spring before the pathogene has spread to any distance in the soil. 



The proximity of the contaminated beds at Yonkers to the Boyce 

 Thompson Institute seemed to offer an excellent opportunity to attempt 



