VARIETAL SUSCEPTIBILITY OF OATS TO SMUTS 7 
The methods employed were similar in all essentials to those 
previously described. The varieties were grown in rod rows, and 
the usual method was to have three plats arranged side by side. 
The seed inoculated with Ustilago avenae was sown in one plat, 
uninoculated seed was sown in the central plat, and seed inoculated 
with 77. levis in the thud plat. 
Certain varieties also were used as checks and were repeated fre- 
quently in the series of varieties and strains. Victor and Canadian, 
varieties of Avena sativa, and some variety of A. nuda commonly were 
used as such checks, because of their marked susceptibility to the 
smuts. Fulghum, a variety of A. sierilis, and Black Mesdag, a 
variety of A. sativa, were included because of then high degree of 
resistance. Generally some strain of A. brevis and A. strigosa also 
were included as checks. The use of these checks served a twofold 
purpose. If the susceptible check varieties had consistently high 
percentages of infection throughout the plat, it made possible more 
definite conclusions regarding the resistance of the other varieties. 
On the other hand, the highly resistant strains were given all possible 
opportunity to become infected. 
The spores used in the foregoing experiments usually were obtained 
from a plat of some variety of Avena nuda and kept over until the 
following season. 
The seed to be sown was placed in small packets, each sufficient for 
sowing a rod row. The endeavor was to bring to maturity somewhere 
between 75 and 100 plants to the row. Accordingly, the seed was 
not sown as thickly as is ordinarily the rule in oat nurseries. A small 
quantity of the spores of Ustilago avenae was placed in each packet of 
one lot and mixed with the seed by a thorough shaking. In a similar 
fashion the seed in the third lot of packets was inoculated with spores 
of the covered smut. The seed for the second lot was not inoculated. 
The data were collected as soon as possible after the varieties began 
to head. Consequently, by the time the oats in the check plat were 
mature practically all of the rows in the inoculated plats had been 
removed. 
The seed was obtained from a number of sources. Many of the 
varieties originally came from Doctor Bubak, at the time Director 
of the Botanical Garden at Tabor, Bohemia. Dr. W. C. Etheridge 
furnished practically a complete set of the varieties which he de- 
scribed in his memoir on the classification of oats. A very large 
collection of varieties has been furnished by T. R. Stanton, agrono- 
mist in charge of oat investigations, United States Department of 
Agriculture. The writers are especially indebted to Mr. Stanton for 
a great deal of assistance in identifying the different varieties grown 
in the experiments. Prof. J. H. Parker, of the Kansas Agricultural 
Experiment Station, and Dr. C. E. Leigh ty, of the Office of Cereal 
Investigations, United States Department of Agriculture, each fur- 
nished a few varieties. 
The results obtained are presented in Table 2. In this table the 
species are arranged in alphabetical order, with the varieties simi- 
larly grouped under each species. The U S. N." numbers recorded 
are those of a series used by the senior writer in the nurseries of his 
previous experiments. A variety having a Cereal Investigations 
accession number has that number added for further identification. 
