44 CORN AND GRASS. 
STEM EELWORMS.—“Tulip-root” and “Segging” in Oats, 
“Stem-sickness” in Clover, caused by Stem Helworms, 
Tylenchus devastatrix, Kuhn. 
TYLENCHUS DEVASTATRIX, Stem Eelworms.—Anterior portion of female showing 
mouth-spear; and embryo in egg; all greatly magnified: anterior portion magnified 
440 times. From figures by Dr. J. Ritzema Bos. 
During the past season I have had more communication than usual 
about Stem Helworm attack, including in the observations damage 
to Oats (‘* Tulip-root’’ and ‘‘Segging’”’); to Clover (Clover ‘‘ Stem- 
sickness’’); and also to Onions (the ‘‘ Onion-sickness”” of Holland). 
All of these attacks are caused by one kind of Helworm, scientifically 
Tylenchus devastatria. 
In the case of the Onion attack, although it has long been the 
cause of great loss to Onion growers in Holland, and in all probability 
has been doing mischief here, and one at least of the unexplained 
causes of Onions “ going off,” yet it has not until the past summer 
been identified as one of our own erop pests; therefore, to attract 
attention to it, I have placed the details of the attack separately under 
its own crop heading of ‘‘ Onions.” 
With regard to Kelworm attacks to Oats and Clover, though it is 
well known that when Eelworm is established in any special field it 
will attack year after year (or at a distance apart of several years) any 
crop put in which is liable to its infestation; yet this certain fact is so 
much overlooked in common field cropping, that I have particular 
pleasure in being allowed to give the observations of such a well-known 
and skilled agriculturist as Mr. Clare Sewell Read as to sequence of 
attacks, in addition to the others referring to the Clover and Oat 
attacks separately. 
