BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 47 
In the North Central region there was considerable spread of the 
rust. It was found on Ribes for the first time in 13 counties in 
Ohio, 9 in Iowa, 1 in Michigan, 2 in Wisconsin, and 2 in Minnesota. 
In 67 percent of these counties the rust was found on the cultivated 
black currant {Ribes nigrum), indicating the importance of this 
species in the distribution of the disease. Blister rust on white pine 
was found in 2 new counties in Ohio, 2 in Michigan, 2 in Minnesota, 
and 1 in Wisconsin. In Wisconsin the rust has now been found in 
every county in the State on either pine or Ribes, or on both host 
plants. In Ohio the disease spread as far south as Champaign 
County, where it was found on Ribes. This is an extension of about 
50 miles over its previously known distribution and may be the 
result of long-distance spread of aeciospores from the north and east. 
In Iowa most of the spread occurred in the northeast quarter of the 
State, although O'Brien and Dickinson Counties, in the northwestern 
part, were reported infected. All the findings in Iowa were on R. 
nigrum. It appears likely that most of the spread in Iowa came 
from pine infection centers in southern Minnesota. 
In the Northeastern States the rust is generally prevalent on 
both host plants and in nonprotected areas it continues to spread 
unchecked from Ribes to pines. Observations on the spread of the 
disease in protected areas show that effective control has been ac- 
complished and that new pine infections in such areas are relatively 
few or absent. The rust is so widely distributed over the North- 
eastern States that the region is considered generally infected. 
In the western white pine region of eastern Washington, northern 
Idaho, and western Montana no extension of the disease was reported 
over that known at the end of the calendar year 1938. Additional 
infection on Ribes was observed this year in Glacier National Park, 
and the disease continues to spread rapidly and destructively in 
many of the young western white pine stands of northern Idaho 
that have not been reached in Ribes eradication work. There are 
still nearly 800,000 acres of unprotected white pine on quality sites 
in this region. 
In the sugar pine region the extended hot and dry weather and 
the lack of favorable winds during the period of canker sporulation 
appear to have checked the spread of the rust except in the immediate 
vicinity of pine-infection centers, and even here infection on Ribes 
bushes was relatively light, considering their high susceptibility 
and the volume of aeciospores produced. This is not unusual, as vein's 
in which conditions were unfavorable for rust spread have occurred 
in the past in other parts of the country. 
An examination of the pine-infection area along the east fork 
of Indian Creek on the Klamath National Forest in California 
showed that a high proportion of scattered sugar pine seedlings and 
saplings were diseased. Also, trees located close to Ribes san- 
guineum bushes scattered through the timber on the hillsides were 
severely infected, and hundreds of cankers had produced spores 
this year in contrast to a few in any previous year. 
The results of scouting in California during the season were neg- 
ative with respect to the discovery of new locations of infection on 
Ribes, and there was not only no southward extension of the rust 
on Ribes beyond that previously reported, but no infect ion was found 
