228 
Journal of Agricultural Research 
Vol. XXV. No. S 
As no buds or shoots are found on the main root on the other side, one 
can be rather sure that the fungus in this case traveled back up the root 
instead of outward, as might be expected. The fact that the root 8 
inches distant did not carry mycelium is positive proof that 112-C was 
primarily infected by sporidia. There is no apparent reason why the 
fungus might not continue its growth back toward the parent, and thus 
a parent plant system might become infected through the rust from its 
root shoots at some distance away. As one finds, then, two infected 
plants connected by a root carrying the fungus, it is impossible to de¬ 
termine with certainty after the second year which plant was the one 
primarily infected. 
Fig. 6. —Parasite invades root from stem. Diagram of basal part of plant 112 C. Shaded parts of stem 
represent 1921 growth; brandies unshaded, 1922 growth. Mycelium found in cambium, phloem, and 
cortex of root between C and C\ No mycelium in root 8 inches to the right of C\ See text. 
Where one finds in nature several infected plants attached to the same 
root runner, sections will usually show hyphae in the connecting root. 
While the writer has not happened to find in nature cases where no 
mycelium was present, doubtless independent infections of two or three 
plants which are derived from the same root runner do occur here also. 
The rust which occurs on young basal shoots of old plants undoubtedly 
fails in many cases to invade a horizontal root runner and would thus 
be unable to reach other plants that had arisen in the same manner. 
The root system of an infected wild high bush blackberry growing in 
sandy soil was dug up April 13, 1921. It was found that a rusted plant 
was attached to a root runner 18 feet distant from the original plant 
which was now dead and decayed. Its large root, \ % inches in diameter, 
however, was still alive. Between these two plants there were two small 
plants not infected, attached to the same root. Passing out in the other 
direction from the parent, the root runner was followed 12 feet farther. 
