BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 53 
The blister rust control area comprises 27,500,000 acres. Over 
23,000,000 acres have been worked once, and 8,000,000 acres twice. 
Additional workings have been given to about 2,000,000 acres. About 
12,738,000 acres, or 46 percent of the control area, are on maintenance, 
4,000,000 acres are unworked, and 10,686,000 acres require additional 
rework before they will reach a maintenance status. 
The environs of 12 nurseries containing over 65,000,000 white pines 
for forest planting were reworked during the year, and 2,067 ribes 
bushes were removed from 6,153 acres. In addition, 68,702 infested 
white pines, mostly in plantations, were saved by the cutting off of 
diseased parts. Cooperating State and local agencies provided funds 
and services amounting to $673,000 for removal of ribes on State and 
private lands. 
Rust spread in southern Appalachians 
Blister rust was found for the first time on ribes in eight counties 
in North Carolina and four in Tennessee. The range of the disease 
was thus extended about 50 miles southward and approximately 125 
miles westward in the southern Appalachians. The disease was re- 
ported on white pines for the first time from one additional county 
each in West Virginia, Wisconsin, and Minnesota. It is now present 
throughout most of the range of the commercial white-pine forests. 
In the sugar-pine region the spread of the rust has been retarded by 
elimination of infection centers. The diseased trees are destroyed and 
the ribes within infecting range of the pines are removed. 
Ribes sprayed with 2,4-D formulations by helicopter 
The first tests of the helicopter for spraying ribes with 2,4-D were 
made on the Sierra National Forest in California. A Bell model 
47B-3 equipped with a 44-nozzle boom was flown within 30 feet of the 
ground at land elevations of 5,200 to 6,000 feet. The maximum spray 
load carried was 20 gallons. In 54 flights 18 plots, totaling about 38 
acres, were sprayed with 575 gallons of various formulations and 
dosages at ground speeds of about 30 miles per hour. Observations 6 
weeks after treatment showed that the 2,4,-D ester in Diesel oil was 
generally more toxic to ribes and associated brush than the water solu- 
tions of the esters or salts. Significant damage to Ribes roezli and 
R. nevadense and other susceptible plants was caused by 16 ounces or 
more of 2,4-D acid per acre. Damage to ribes was spotty wherever 
these plants were screened by other vegetation. In general, the ap- 
parent kill of ribes and susceptible brush is closely related to the dens- 
ity of the spray deposit. Most uniform coverage was obtained on 
plots where slope and ground obstructions permitted spraying from 
opposite directions. Final results of the spray tests will be deter- 
mined when the plots are checked during the 1949 growing season. 
Survey shows rust losses in western pine stands 
A survey was carried on to determine the white-pine stocking and 
the damage from blister rust in reproduction and pole-size stands of 
western white pine in the Inland Empire. About 1,000 miles of strip 
were run on the survey. The results showed that the original stocking 
in these stands had been reduced by 25 percent from blister rust, leav- 
