8 CLOVER-SICKNESS. 
Ritzema Bos in 1889; and as a threadworm or Nematode-dXi&ok lias 
appeared in Potatoes in the United States, it is probable that this 
same Eelworm is causing it, and that we shall before long find it here.* 
From minute experiment it has been found that by sowing seed of 
plants liable to infestation on earth in which fragments were buried of 
plants containing the “ Stem Eelworm,” that the young plants coming 
up from this seed presently were infested similarly. Thus we prove 
the identity of the kind which causes the attack. Dr. Ritzema Bos (to 
mention one of his many experiments) obtained Tulip-rooted Oats by 
sowing Oats on sand mixed with decaying “ Clover-sick” plants and 
diseased Onions; Rye sown over infested Teazel-heads was found by 
Dr. Kuhn to become infested; I have myself similarly caused infestation 
in the Turnip, although this is not a plant considered to be usually 
liable to it. 
On the broad scale of field cultivation I have notes of Clover-plants, 
“stem-sick” from this Eelworm, occurring on land where Tulip-root 
had been bad in Oats the previous year, and of Tulip-rooted Oats 
occurring on land where the Clover had been “ sick ” the previous year. 
It is highly desirable , where there has been stem Eehvorm-attack, to take 
as the next crop something which is not known to suffer from it. 
Barley appears to be safe, and Wheat little attacked; and Flax, 
Peas, and Cabbage to be safe. 
Turnips do not appear to have been noticed as infested, excepting 
in the single instance of my own experiment; and Mangolds appear to 
be safe from this attack, although sometimes suffering from another 
kind of Eelworm. Carrots and Parsnips are also, as far as we know, 
safe; and Carrots are especially mentioned by Dr. Kuhn as a good crop 
on land ploughed in to cure Eelworm infestation. 
Cultivation of the land is another important point. If the land is 
worked by a plough with skim-coulter attached so as to pare off a thin 
surface-slice and bury it fairly quite down, and turn the clean earth on 
to the surface, in this way all the Eelworms (whether in the plants them¬ 
selves, or those which will in all likelihood have left them and be 
lying quite in the surface soil) will be safely turned down out of the 
way, and (unless they are ploughed again to the surface) will be put 
out of the way of giving further trouble. In like manner, trenching 
* The attached Potatoes are stated to be distinguishable by the entire surface, 
but more especially the sides, being scattered more or less thickly with little 
tubercle-like swellings, each surrounded by a slight depression, and beneath these 
the tissue of the Potato is described as being brown, and apparently dry to the 
depth of about the twelfth of an inch. In this brown, disorganized tissue, which 
appears, from the description, much to resemble the brown, powdery material in 
which we find some of the Eelworms in Tulip-rooted Oat-plants, the Potato Eel- 
worms were found in great numbers. The above is taken from Report by Prof. 
F. S. Scribner in Bulletin (of the present year, 1889) of the Tennessee Agricultural 
Experimental Station. 
