May 19,19*3 
Life History of Stripe Rust 
615 
SEED TRANSMISSION OF STRIPE-RUST INFECTION 
HISTORICAI, DISCUSSION 
The author (6) has reviewed the principal literature upon the subject 
of rust transmission by seed grain and discussed the three theories put 
forth by various writers to explain the means by which such transmission 
may take place. These are the mycoplasm theory, the dormant my¬ 
celium theory, and the seed-bome-spore theory. T^e results of experi¬ 
ments carried on by various workers along this line have also been 
tabulated in the author's previous work (6) on this question. This 
review will not be repeated h^e. In this paper carefully controlled 
field and greenhouse experiments with wheat infected with P. graminis 
tfitici were also conducted. The results of these studies led to the con¬ 
clusion that stem rust is not transmitted from one wheat crop to the 
next by means of infected seed grain. Waterhouse (9), more recently, 
has carried on similar experiments with wheat kernels infected with stem 
rust which also gave negative results. 
Certain European investigators have secured positive results in experi¬ 
ments carried on to determine if P. glumarum can be carried from year 
to year on seed grain. Because of the economic importance of this phase 
of the question in the United States in connection with the spread of the 
rust to regions where it is now imknown, experiments were undertaken 
with stripe rust both in the field and under carefully controlled greenhouse 
conditions. 
EXPFRIMENTAD DATA 
A number of field observations have been made which at first seem 
to indicate very strongly that P. glumarum may be transmitted by means 
of seed. In the summer of 1917, among the increase plots of the Farm 
Crops Department at the Oregon A^cultural College, a plot of Jones 
(Wmter) Fife was found to be heavily infected with stripe rust while 
none of the plots around it was infected to any extent. It was learned 
upon inquiry that the seed from which this plot was sown came from 
McMinnville, Oreg., and it was also learned that seed from the same lot 
sown at McMinnville produced plants that were not rusted. Upon 
close examination in the vicinity of the infected plots, numerous volunteer 
plants of Chul wheat were found which were heavily rusted. A plot 
of Chul wheat which was grown near this field the year before was 
known to have been infected with stripe rust. It seemed reasonable to 
suppose that the rust wintered over on these volunteer plants and in¬ 
fected the Jones Fife. No other very susceptible varieties were grown 
near this section of the field. 
Another case in point which is not so easily explained was noted by 
Dr. A. G. Johnson, of the OflGice of Cereal Investigations, United States 
Department of Agriculture. Doctor Johnson found stripe rust on 
barley varieties in the nursery on the Belle Fourche Experiment Farm, 
at Newell, S. Dak., in August, 1917. These barleys were quite uni¬ 
formly infected, and no other stripe rust was noted at Newell. The 
writer visited Newell in 1918, but was able to locate no stripe rust on or 
near the experiment station grounds. Some of the same seed from 
which these infected varieties had been grown was secured from Mr. 
John H. Martin, then of the Belle Fourche Farm, and sown in Septem¬ 
ber, 1918. The plants from this seed were grown in the greenhouse at 
39364—23 -6 
