UNITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN No. 1229 



Washington, D. C. T March 1, 1924 



THE STEM NEMATODE TYLENCHUS DIPSACI ON WILD HOSTS IN THE 



NORTHWEST. 



By G. H. Godfrey, Pathologist, Office of Cotton, Truck, and Forage Crop 

 Disease Investigations, Bureau of Plant Industry, and M. B. McKay, Asso- 

 ciate Pathologist, Oregon Agricultural Experiment Station. 



CONTENTS. 



Page. 



Introduction 1 



Symptoms 1 



The causal organism 2 



Distribution 2 



Apparent independence of the two 



hosts 3 



Relation to environment 5 



Page, 

 Origin and dissemination of the 



disease 5 



Tnoculation experiments 7 



Economic significance 8 



Summary 8 



Literature cited 8 



INTRODUCTION. 



Attention has been called several times to the occurrence of the 

 stem and bulb infesting "nematode Tylenchus dipsaci Kiihn {Tylen- 

 chus devastatrix in most of the European literature) on various 

 hosts in America. Byars (-?) 1 mentioned its occurrence on hyacinth. 

 Smith (9) and Byars (2) reported diseases in red clover and straw- 

 berry due to the organism. McKay dealt more at length with the 

 disease in strawberry (S) and later reported its occurrence on alfalfa 

 (6) and wild strawberry, Frag ana chiloensis (7). Godfrey (3) 

 mentioned its occurrence on all the known hosts in America and 

 briefly described the symptoms. This paper deals with the wide 

 occurrence of the pathogen on the wild strawberry and reports an 

 additional host, the false dandelion, Hypochaeris radicata. The dis- 

 covery of the disease on this plant was made by Prof. H. P. Barss 

 and the junior writer together, at Newport, Oreg., in June, 1922. 

 H. radicata is listed by Massalongo (4, p. 8) as being subject to a 

 nematode gall referred to as a " Helminthocecidium," which, judging 

 from the illustration, is clearly the same as the one discussed here. 



SYMPTOMS. 



The symptoms of the disease on the wild strawberry (PI. I, A, B t 

 and C) are in every respect the same as on the cultivated. Swellings 



1 The serial numbers (italic) refer to "Literature cited" at .the end of this bulletin, 

 71560° — 24 



