886 
Journal of Agricultural Research voi. xxiv, no. n 
Certain varieties were represented by as many as 75 plants, others by 
only I or 2, and conditions for infection were perhaps more favorable on 
one side of the field than on the other, so that a full report on these ob¬ 
servations would not fully represent the actual degrees of susceptibility. 
Among others, the following seedlings were found to be quite badly 
infected: Ranere X Cuthbert,^ Cuthbert X R. lasiostylus, La France X 
Ranere, Van Fleet X Ranere, Laxtonberry X Ranere, Cuthbert, Gregg X 
Cuthbert, Brighton X La France, Brighton X R, lasiostylus, R. coreanus 
X Brighton, Shaffer seedlings, Shiebley X King, R. leucodermis X King, 
Newman 23 X R. coreanus, seedlings of Hailsham open pollinated, Syra¬ 
cuse open pollinated, Brighton selfed. The Ranere (St. Regis) was 
infected, but not as heavily as were the Cuthberts. 
Certain hybrid seedlings were so severely infected as to result in almost 
complete defoliation, petioles and canes also being attacked. These very 
susceptible kinds include such hybrids as June X Cuthbert, Latham X 
Brighton, Latham X Ranere, Erskine X Ranere, R. coreanus X Brigh¬ 
ton, etc. 
A number of varieties in this plot were only slightly infected, but, as 
previously noted, the number of plants in many cases was too small to 
prove that they were resistant. About 50 plants each of the following 
forms were carefully examined at this time, but no rust was found: 
Rubus IdaeuSy open pollinated seedlings of the Mahdi (which is a cross 
between R. I^eus and a European blackberry), R. innominatus X Ant¬ 
werp, R. innominatus X King, R. innominatus (open pollinated seedlings). 
A few self-pollinated Cuthbert seedlings in this field showed no rust, but 
many plants of this variety in a garden near by were heavily infected. 
Separated from these plots by about 40 rods was a third plot, in which 
several plants of wild Rubus occidentalis, R. strigosus, R. leucodermis, 
King, Cuthbert, Ranere, etc., were growing. A few pustules were found 
on one unnamed variety. A month later the rust was very abundant on 
the King, June, Newman 23, Cuthbert, and some was found on R, 
strigosus, but R. occidentalis, R, Idaeus (Hailsham variety), and 5 Asiatic 
raspberries were not affected. 
Mention has been made of finding the rust on leaf stalks and canes. 
The cankers on the latter are sometimes 2 or 3 inches long. A species 
of Gloeosporium (not anthracnose) was also common in large cankers on 
the varieties whose canes were most heavily attacked by the rust. It is 
possible that this fungus became established in the lesions first formed 
by the rust; at any rate the combined effect of the two fungi will be to 
kill the canes. The calyx and carpels of late-fruiting or everbearing 
varieties were sometimes badly rusted. It is certainly curious to see 
the golden-yellow pustules deeply embedded in the juicy red carpels. 
There was more rust on the fruit of a late-flowering form of R, strigosus 
than on the leaves. 
A press of work prevented a satisfactory examination of species of 
wild and cultivated raspberries in other localities to learn how common 
the rust was in the vicinity. It is clear, however, that the rust had 
found in these hybrids very susceptible hosts. 
3 The Black Pearl, Kansas, Cumberland, Gregg, and Plum Farmer, are American horticultural varieties 
of black raspberry which were originated as seedlings or by selection from Rubus occidentalis, of which 
R. leucodermis is a western variety; the Shaffer, Columbian, and Royal Purple are of American origin, 
probably derived from the form Rubus neglectus, which is a hybrid between R. strigosus and R. occidentalis; 
the Cuthbert, King, Victor, Erskine, June, Eatham, Ranere, and Brighton, are American horticultural 
varieties of red raspberries, and related to R. strigosus; R. Idaeus, the Antwerp, La France, Laxtonberry, 
and the Hailsham, are European red raspberries; R. coreanus and R. innomialus are native of China. 
