BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 73 
Kibes destroyed with chemicals 
Several kinds of equipment, such as power sprayer, turbine blower, 
knapsack, Hi-Fog gun, and helicopter, were used by the cooperating 
agencies in applying 2,4-D and 2,4,5-T to destroy millions of ribes 
Lushes on about 5,190 acres in the western white and sugar pine 
regions. Increasing use was made of chemicals to destroy ribes on 
logged-over, burnt, upland, and stream-type areas. Concentrations 
of ribes on these sites can be -effectively treated with chemicals at a 
traction of the cost of other methods. Only minor use of chemicals 
is feasible in eastern white pine regions, where chemicals were most 
effective in destroying large patches of wild black currant bushes. 
This was accomplished at about one-fourth the cost of hand methods. 
The Bureau cooperated with the School of Forestry of the Univer- 
sity of California and the California Forest and Range Experiment 
Station in an economic study of sugar pine management in the Pacific 
coast region. Economic standards were developed for selecting stands 
for protection against blister rust. They were integrated with climate 
and disease-survey information and techniques were developed for 
their application. Applied on a practical basis to 147,000 acres of 
sugar pine lands, they brought about the reduction of protective zones 
and the selection of small, highly productive sugar pine stands for 
blister-rust control treatment. The stands were previously excluded 
from control areas because of the high cost of working surrounding 
protective zones. 
Studies initiated on rust resistance in white pines 
A search for western white pines apparently resistant to blister 
rust revealed 59 such trees. From them 2,000 scions were taken and 
grafted on white pine seedling transplant stock. With assistance from 
the Institute of Forest Genetics, California Forest and Range Experi- 
ment Station, 420 controlled pollinations were made between 25 of 
the resistant trees. They included 80 different crosses between rust- 
resistant white pine trees. The progeny from the crosses will be used 
for determining the inheritance of rust resistance. 
Studies were started to determine whether the blister rust fungus 
develops physiological races and, if so, whether they differ pathologi- 
cally in their ability to attack different species and varieties of white 
pines. The studies, carried on cooperatively by the University of 
Minnesota and the Bureau of Plant Industry, Soils, and Agricultural 
Engineering, are related to the development of rust resistance in 
white pines. 
Rust found in new places 
Blister rust was found on white pines for the first time in Ravalli 
County, Mont., Lemhi County, Idaho, Park County, Wyo., Missouke 
County, Mich., and Amherst County, Va. A small infection center 
was found in Big Canyon drainage at the southern end of the Eldo- 
rado National Forest in California, which extends the infected area 
7 miles southward. From the Lassen Forest northward in California, 
surveys show that outside control areas the disease is rapidly increas- 
ing on pines. On ribes bushes, the rust was found in Cascade County, 
Mont, Lemhi County, Idaho, and Park County, Wyo. 
