196 CKOWN-GALL OF PLANTS. 



Under date of September 24, 1909, Mr. Frank N. Meyer, agri- 

 cultural explorer for this Department, sent from Angers, France, a 

 young plant of Arbutus unedo bearing root galls. From these galls 

 bacterial colonies resembling the daisy organism were plated out 

 and galls produced on sugar beet by pure-culture inoculations 

 (PL XXIV, A). 



Lounsbury has reported it, or something closely resembling it, as 

 prevalent and injurious on the willow in the Transvaal and Cape 

 Colony, South Africa, where it appears to be a new trouble, having 

 come to scientific attention first in 1899. He sent some of these 

 \\^llow galls to us and from one of them a colony was plated which 

 produced slow-growing galls on the daisy and upon weeping willows 

 (PL XXXV, fig. 1). 



HOTHOUSE PLANTS. 



Other than those already mentioned we have found what may be 

 this disease on roots of lettuce (PL XXXVI, fig. 2). Our attention 

 was called to this by Mr. W. W. Gilbert, a Bureau colleague, who 

 turned the material over to us with the statement that he could 

 not find any nematodes in the root swellings. We also failed to 

 find them. Thereupon poured plates were made. 



The plants shown on the plate were photographed natural size. 

 They had been growing nearly three months and were badly dwarfed. 

 There were many such plants in the hothouse and all had similar 

 galls on their roots, and no other assignable cause for their stunted 

 appearance, since the roots of those lettuce plants in the same house 

 which had made a good growth were free from these nodules. The 

 only other disease in the house was an occasional case of the drop. 



Agar-poured plates were made from one of these galls after prop- 

 erly sterilizing the surface and colonies obtained which resembled 

 those of Bacterium tumefaciens. With subcultures from half a 

 dozen of these colonies inoculations have been made into the roots 

 of young sugar beets, but no galls have appeared to date (13 days). 



BEST METHOD OF DEALING WITH THE DISEASE. 



Up to this time the best method of dealing with this disease remains 

 the old one of strict inspection of nursery stock and the condemna- 

 tion of all trees and shrubs found diseased. In individual cases 

 this undoubtedly works hardship to the nurseryman, but, on the 

 other hand, to allow him to sell galled trees injures the fruit grower, 

 serves to distribute the infection broadcast, and tends to destroy 

 his own reputation. The nurseryman's remedy lies in careful 

 methods and the abandonment of infected soils. 



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