25 
BREEDING AND SELECTION STUDIES OF VARIETAL RESISTANCE TO BUNT. 
The first observations at Pullman, Wash., on the differences in 
varietal resistance were made in breeding and selection studies in 
the spring of 1913. Sowings of Early Wilbur, Red Chaff, and 
Pacific Bluestem were made on seven different dates. These range 
from high to medium susceptibility in the order named. Through- 
out this series, as well as in other years when they happened to be 
used for various experiments, their relative susceptibility remained 
the same. The results are shown in Tables 19 and 20. 
In Table 21 the proportion of bunted heads in such plants as con- 
tain both wheat heads and heads of bunt is given. In those varieties 
which show the lowest percentage of bunted heads there is a rela- 
tively low percentage of such heads in partly infected plants. 
Table 21. — Results of an experiment to determine relative varietal susceptibility of 
wheat to bunt in a plat sown at Pullman, Wash., October 14, 1916. 
Variety. 
Red Russian 
Fortvfold.... 
Turkey i 
Winter Fife. 
Hybrid 60... 
Hybrid 128.. 
Hybrid 123.. 
Hybrid 143 . . 
Little Club.. 
Production of bunted plants 
and heads (per cent). 
Plants. 
Bunt 
free. 
55.3 
47.7 
73.3 
38.1 
39.2 
23.5 
20.3 
14.4 
30.0 
Wholly 
bunted. 

7.1 
1.3 
38.1 
48.0 
55.4 
58.5 
72.0 
60.0 
Partly 
bunted. 
44.7 
45.2 
25.4 
23.8 
12.8 
21.1 
21.2 
13.6 
10.0 
Bunt- 
ed 
heads. 
18.7 
33.7 
9.3 
53.3 
52.8 
66.1 
67.1 
84.3 
61.3 
Variety. 
Salzer's Marvel . . 
Florence 
Hybrid 153 
Triplet 
White Track 
Winter Bluestem 
Coppei 
Washington 626. 
Production of bunted plants 
and heads (per cent). 
Plants. 
Bunt 
free. 
37.9 
72.3 
27.1 
11.0 
55.6 
21.1 
25.6 
15.4 
Wholly Partly 
bunted, bunted. 
15.5 
1.3 
65.6 
63.0 
16.6 
45.8 
34.4 
42.3 
26.4 
7.3 
26.0 
27.8 
33.1 
40.0 
42.3 
Bunt- 
ed 
heads. 
34.8 
6.3 
61.2 
77.3 
34.8 
64.0 
58.9 
65.2 
1 The 58 bunted Turkey (Washington No. 326) plants produced a total of 633 heads, 575 of which were 
bunt free, 37 partly bunted, and 21 wholly bunted. 
It seems that no variety yet tested is able to resist the entrance of 
the bunt fungus into the seedling when temperature and moisture 
conditions are favorable and when the infective stage of the fungus 
synchronizes with the infectible stage of the wheat. Certain varieties, 
however, are able in varying degrees to produce wheat in spite of such 
infection. (See Turkey and Florence, Table 21.) This is shown by 
the investigations of the writers as well as by those of other workers. 
Such characters or factors might conceivably fall into two classes : 
(1) Those that tend to produce such a rapid development of the plant 
or certain parts of it that the fungus is simply outgrown or left behind 
in all or part of the culms of a plant and (2) morphological, physio- 
logical, or chemical characters that tend to overcome, suppress, or 
inhibit the growth and distribution of the fungus within the host. 
The evidence strongly favors the second set of factors, for if the faculty 
to produce wheat in spite of infection depended on the ability of the 
plant to grow away from the fungus merely by rapid development com- 
parative freedom from bunt would appear to be a characteristic of 
long-strawed varieties. This is not the case, however. For example, 
the susceptible Winter Fife is among the varieties having the longest 
straw, while the resistant Florence is comparatively short. Again, a 
relation between comparative freedom from bunt and rapid growth 
