BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 73 
save valuable crop trees that otherwise would be killed by the rust. 
Fifteen forest tree nurseries and their environs were surveyed dur- 
ing the year. These nurseries annually produce millions of young 
white pine for forest planting. During the surveys 2,075 ribes were 
removed from 7,000 acres of land. These surveys, which are made 
periodically as part of a continuing check on such nurseries, assure a 
source of rust-free planting stock. The average of 3.5 ribes bushes per 
acre shows that a high degree of protection is maintained. 
There are nearly 26 million acres in control areas. The disease is 
under control on more than 16 million acres, or 62 percent. The re- 
maining 38 percent is in various stages of completion. Some of it 
needs initial work. All of it needs rework to establish control of the 
disease. Thereafter, control areas need some follow-up work periodi- 
cally to maintain this condition. 
First record blister rust infections on white pine were reported 
during 1952 from Monroe County, W. Va. ; Smith and Washington 
Counties, Va. ; Carbon County, Mont.; Tama and Jones Counties, 
Iowa ; Lapeer County, Mich. ; and Houston County, Minn. Rust on 
ribes was reported for the first time from Carbon, McCone, and 
Prairie Counties, Mont., and Albany County, Wyo. These ribes in- 
fections extend the rust 200 miles eastward in Montana and 225 miles 
southeastward in Wyoming. There was no southward extension of 
the rust in the Sierra Nevada Mountains. 
Improved equipment is extending chemical treatment of ribes to 
remote areas, and the use of chemicals in areas supporting high ribes 
concentrations is giving more efficient ribes suppression at lower 
costs. Chemicals do the initial job cheaper and reduce the amount of 
rework. On cutover areas containing numerous ribes, chemical treat- 
ment has become standard practice in western white and sugar pine 
areas. In all white pine forests, chemicals are proving advantageous 
for treating small patches of dense ribes growth occurring within 
large areas having a low ribes population. Hand crews are trained 
to recognize, mark, and bypass such patches, leaving them for later 
chemical treatment. 
A 60-pound portable power sprayer that utilizes an eccentric-type 
rubber impeller pump and a iy 2 hp. air-cooled motor was assembled 
on a special pack frame. Accessories developed for this sprayer 
include a 200-gallon, self-supporting, collapsible, canvas tank, and 
a 5-gallon combined carrying tank and gas tank fitted for direct 
attachment. This unit, field tested in Idaho and California, will 
make possible the power spraying of troublesome ribes not accessible 
to truck-mounted sprayers. 
During July 1952, 160 acres were sprayed with low dosages of 
2,4-D and with pellets containing a volatile ester of 2,4-D. These 
sprays and pellets caused sufficient injury to ribes to justify further 
tests of these low-cost methods of applying chemicals. The 2,4-D 
pellets appeared to be highly selective on the sensitive Ribes roezli 
and to have little or no toxicity to valuable trees and shrubs more 
than 2 feet tall. Repeated pellet applications can be made without 
damaging any except the most sensitive plants under this height. 
The success of these sprays, which are intercepted to some extent by 
trees and shrubs taller than ribes, depends on the development of 
herbicides more selective and more readily translocated. 
