442 
Journal of Agricultural Research 
Vol. XXVII, No. 7 
part of the culms until the shoots were from i to 3 inches high. The 
secondary shoots arose from the crown or from the first, second, and 
third nodes above the ground. Infection often was noted on shoots 
which arose from these points of origin. Plate 3, A, shows a cut-back 
plant with an infected shoot which arose from the second node, or the 
first node above ground, of a culm which had been cut. This infected 
shoot from the second node is enlarged in Plate 3, B. 
From the fact that the infected shoots often arise from the nodes 
above ground, where the chances for infection are very few, and from 
the difficulty encountered in producing infection where inoculations 
were made after the plants were above ground, it would seem that the 
smut appearing on the secondary shoots arose from hyphae already 
inside the tissues of the host plant. 
Seventeen winter varieties and 11 spring varieties were used in experi¬ 
ments to study the effect of cutting back wheat plants on the appearance 
of infection. These varieties were resistant, slightly susceptible, and, 
in a few instances, quite susceptible in previous varietal experiments. 
A susceptible spring and a susceptible winter variety, Bobs and Harvest 
Queen, were used as controls for infection. Four rows of each veriety 
were sown 6 inches apart, placing 18 inoculated seeds 2 inches apart in 
each row. The plants in row 1 of each variety were cut back to about 
1 inch in height when they had two leaves and were two to three weeks 
old. The plants of the second row of each variety were cut back to 2 to 
3 inches in height when they had two or three small culms, or when 
infection was showing in the susceptible varieties used as controls. Plants 
in the third rows were cut back when beginning to head, and those in 
the fourth rows were left uncut and used as controls on the plants which 
were cut back. These different series of cut-back plants are hereafter 
referred to as rows 1, 2, 3, and 4. 
The appearance of smut lesions was watched for closely, and all in¬ 
fected plants removed as soon as observed, so that in each instance 
only the smut-free plants were cut back. Of the 11 spring varieties 
treated in this manner 3 showed no infection and 2 an infection of 
1.6 and 5.4 per cent, respectively, but which did not seem to be in¬ 
fluenced by cutting back the plants. However, 5 varieties developed 
smut in the cut plants either earlier or in a greater percentage than in 
the plants which were not cut back. Of the 17 winter varieties, 10 
showed no smut, while 4 showed only one or two infected plants. 
Thus in only 3 winter varieties was the development of smut in¬ 
fluenced to any extent by cutting back the plants. The percentage of 
plants infected in each row of the 8 different varieties which became 
infected is given in Table IX. 
There was no uniform plant response from each variety at each stage 
of development when cut back. In all varieties where die plants were 
cut back in the two-leaf stage, there was a greater percentage of infec¬ 
tion than in the control rows which were not cut back. There was con¬ 
siderable variation in the percentage of infection in rows 2 and 3. More¬ 
over, it was observed that clipping the culms not only influenced the 
percentage of infection, but, in many instances, the interval between 
sowing and appearance of smut was considerably shortened. 
Clipping the plants after they had begun to head was the most favor¬ 
able with regard to both the percentage and the appearance of infection 
in Bunyip. Small, secondary shoots at once began to develop in row 
3, and the lesions appeared 17 days earlier in this row than in rows 2 and 
