VARIETAL SUSCEPTIBILITY OF OATS TO SMUTS 37 
tive results were obtained with U. avenae in the total of 850 plants 
grown. 
Three strains of Avenafatua were grown, and all proved susceptible. 
Five strains of Avena ludoviciana were grown, and four of them 
proved moderately susceptible. The fifth strain was highly resistant. 
Seven strains and varieties of Avena nuda were grown. These 
were all highly susceptible to both smuts. 
Avena sativa was represented by over 90 varieties and 182 strains. 
These showed great variation in their susceptibility. A few proved 
to be very resistant, including Black Mesdag, Culberson (S. N. 295), 
Caucasus, Danish Island (S. N. 311), and Siberian (S. N. 323). A 
larger number proved to be highly susceptible, including Canadian, 
Early Champion, Golden Drop, Irish Victor, Japan Selection, June, 
North Finnish, Sixty-Day, and Victor. The greatest number of the 
varieties, however, may be placed in groups intermediate between 
these two extremes. Several varieties, including Bicknell ([selec- 
tions] S. N. 341 and 342), Black Diamond, Danish, Danish Island 
(S. N. 149), Early Gothland, Rossman, and Scottish Chief, appeared 
to manifest a greater susceptibility to Ustilago avenae than to U. 
levis. The reverse seemed to be true in the case of C. I. No. 620 (S. N. 
148), Green Russian (S. N. 203 and 314), Monarch (S. N. 161), and 
Tobolsk (S. N.122). 
All the varieties of Avena sativa orientalis appeared to be susceptible. 
The wild forms of Avena sterilis were moderately susceptible to 
both smuts. The cultivated forms, such as Burt, Fulghum, Red 
Rustproof, and other varieties, possess a marked resistance to both 
smuts. 
Avena strigosa was represented by four strains. No infected 
plants were observed, although 4,824 were grown in the series inocu- 
lated with Ustilago avenae and 3,736 in the series inoculated with 
U. levis. 
A number of varieties were grown in the greenhouse. The results 
were quite comparable to those obtained in the field experiments. 
Resistant varieties maintained their resistance to both smuts, and 
susceptible varieties were attacked severely. 
Under greenhouse conditions the formation of pustules of smut 
spores on the upper leaves of susceptible varieties was conspicuous 
in both Ustilago avenae and U. levis. 
