PLATE 6 
A. —Primary systemic infection of Kittatinny blackberry. The axial bud of the 
shoot inoculated in 1921 developed at once into a branch 2 feet long. The terminus 
of this branch, instead of being winter-killed, as always occurs in normal canes in 
our climate, remained alive and its terminal bud (a 7 ) proliferated into a new shoot 
(a) in 1922. Mycelium was found only in the pith at a in the new shoot and at c in 
the old cane; at the node between the old and the new growth and where leaves were 
attached, mycelium was found in the pith and in the medullary ray gaps. A cross 
section of this cane at c is shown in Plate 2, C; second ring of wood, y, is being devel¬ 
oped on the side below a proliferating shoot from an axial bud. 
B. —Contrast the type of infection shown here with the localized infection shown 
in Plate 3. The old cane, originally inoculated when a shoot, had died during the 
early summer, but the mycelium was soon able to reach the root which lay near the 
surface of the soil, with the result that several buds were developed along the fusiform 
enlargement of the root, all of the new shoots being systemically infected. Since 
the fungus is now established in the runner, the root system must be destroyed to 
prevent the spread of the parasite. In case of a localized infection at the nodes some 
distance above the surface of the soil, the rust disappears along with the natural death 
of the cane at the close of the season. 
