54 ANNUAL REPORTS 01 DEPABTMXNTO] AQRICULTURB, Lfl 
ing potent ial t imber volumes at L20 years averaging L5,750 board feet 
of white pine per acre. On area- mere control baa been established, 
tlic future vield baa been estimated at 5 billion board feet On areas 
pari ially protected an additional yield of 7 billion board feel depends 
upon completion of ribes eradication to prevent further losses. Each 
year that control work is delayed approximately 3 percent of tin- -tat id 
i- becoming fatally infected. Rum infection occurring through L937 
is responsible Tor a Large part of the damage expected in pole-size 
white-pine timber, although where ribes were present, considerable 
new damaging infection occurred in L941. The amount of damaging 
in feet ion in pole stands parallels that in reproduction under similar 
condil ions. 
Barberry Eradication To Control Stem Rust 
IS etc and uncommon races of rust found on barberry 
The production and perpetuation of races of the stem rust fungus 
on barberry bushes was again demons! rated in L9 K A different rare 
of the disease was lom id for <'Vorv 3% isolations made from stem rust 
on barberry bushes. In comparison, a different race was identified 
for every 71 isolations made from rust on grains and grasses. Five 
unusual races and two new ones were identified from the disease on 
barberry. Outside of barberry-infested areas only races 38, 17. and 
56 of the rust fungus of wheat were important They made up 98 
percent of more than 1,700 isolations. 
Race 15 of the wheat stem rust was isolated from infected barberry 
leaves obtained from Pennsylvania, Virginia, Ohio. Michigan, and 
[llinois. Race L5B, a biotype of face 15, was also identified from the 
Pennsylvania collections. This is a virulent race, which can attack all 
the commercially grown wheat-. In one local stem rust spread from 
barberry to wheat in Pennsylvania, L9 face- of the disease were ob- 
tained from 8 collections. From another spread 25 races and biotypes 
were obtained from 20 collections. Race 11 was the most virulent 
found in this group. Some other- are dangerous because they can 
attack -nine of the parent varieties used in the wheat-breeding pro- 
gram. Race 7 w a- found on oats growing adjacent to barberry in Sew 
York. This race attack- the newer oat varieties now iii commercial 
production, but it is.not yet abundant or widespread. 
Stem rust light in 1948 
Stem rust was not of general economic importance in L948 in the 
States participating in barberry eradication. Destructive local epi- 
demics starting on barberries occurred in Pennsylvania, Virginia, 
and West Virginia, 'There was also beavy stem rust on wheat in 
limited areas in southeastern [llinois and southwestern Indiana. In- 
dications are that spores responsible for this infection came from 
farther south, where the di-ea-e overw i nt ere« 1. Stem rn-t appeared 
late in the season in the durum areas of theDakotasandin thePalouse 
district of Washington. Losses of wheat, oat-. Parley, and rye from 
stem rust in the State- participating in barberry eradication have 
gradually decreased a- control work has progressed, as Bhown in 
figure l . 
