2 BULLETIN 1229, U. S. DEPARTMENT OF AGRICULTURE. 



occur on leaves, stolons, and flower pedicels, and even in the flowers 

 and fruits themselves. In the leaves the swellings may be in the peti- 

 oles, either basally, intermediate, or involving the blade. They vary 

 greatly in size, but are often several times the diameter of the leaf 

 stem. The gall on the petiole is spindle shaped as a rule and often 

 an inch or more in length. The swellings in the leaf blades are 

 characteristically crinkled thickenings of greater or less extent, 

 sometimes but not always made more prominent by a reddening 

 against the green background. The leaf symptoms are not likely 

 to be confused with those of any other disease. 



The stolon symptoms are like those on the petioles. A swelling 

 may be anywhere on the stolon, even on its tip. (PL I, B.) This un- 

 doubtedly is a factor in its distribution, the new plant in this case 

 being affected at the outset. Fruiting stems are sometimes badly 

 affected. Usually the galls occur most prominently as long club- 

 shaped swellings just below the blossoms. Often the parts of the 

 calyx or even the petals and receptacle are greatly enlarged and 

 distorted. Fruits in all stages of maturity are sometimes irregu- 

 larly swollen. 



In Hypochaeris the symptoms as seen in the summer and fall con- 

 sist mainly of swellings in the leaves, as they lie in a rosette on the 

 ground. They are often distorted and twisted abnormally, especially 

 when the gall is in the midrib. (PL II.) Here, as in the strawberry, 

 a reddish coloration is sometimes evident on the leaves, but this is 

 not the rule. Evidences of typical galls in flower stems were found 

 as well, in the form of slight increases in thickness at their bases. 

 Stem galls produced by an insect (Aulas? hypochoeridis Kieff) were 

 observed quite frequently also and should not be confused with the 

 nematode swellings. The insect galls as a rule are much larger and 

 more spongy in texture than those produced by the nematodes. 

 Thanks are due to Dr. E. P. Felt, New York State, entomologist, 

 and to L. H. Weld, of the Smithsonian •Institution. Washington, 

 D. C, for identification of the insect. 



THE CAUSAL ORGANISM. 



Examination of the typical swellings and galls invariably disclosed 

 the presence in them of Tylenchus. Those from the strawberry had 

 already been authentically identified as Tylenchus dipsaci. The Hy- 

 pochaeris nematode appeared identical in every way with that found 

 in alfalfa, clover, and strawberry and was so determined. Our iden- 

 tification was later verified by Dr. N. A. Cobb, nematologist, at 

 Washington, D. C., who reported only a slight and insignificant va- 

 riation in measurements from the other strains. 



DISTRIBUTION. 



The information on distribution included herewith, as well as on 

 environmental relations, dissemination, etc., was derived principally 

 from special survey trips made by the writers separately during the 

 summers of 1921 and 1922. In addition, the Oregon State Board of 

 Horticulture, prompted by the seeming advisability of conducting 

 an eradication campaign, made an independent survey in the summer 



