BUREAU OF ENTOMOLOGY AND PLANT (> T A K A X Tl X K 
49 
areas and some stands on national parks, most of the mapping has 
been completed in the western white pine and sugar pine regions. 
Considerable work still remains to be done in the eastern white pine 
regions. Most of the mapping is done during the fall and winter 
months when Ribes eradication is not practicable owing to defoliation 
of the bushes. 
DEVELOPMENTS IN METHODS OF RIBES ERADICATION 
Work was continued on the development and improvement of chemi- 
cal, mechanical, and hand methods for the eradication of Ribes, 
For the first time an effective chemical treatment was devised for 
Ribes triste. The method involved an early- and a late-season spray 
and soil drench of Atlacide at the rate of 2.4 pounds per gallon of 
of water with Tergitol No. 7 as a spreader. Improvements were made 
in the effectiveness of oil sprays on small plants of R. raezli by adding 
to the Diesel oil about 20 percent by volume of a cheap byproduct, the 
sulfur dioxide extract obtained from lubricating oil. 
The scope of mechanical-power methods was extended to the eradi- 
cation of heavy patches of Ribes roezli in upland sites by the use of 
special attachments devised for a 25-horsepower Diesel caterpillar 
tractor. A modified blister rust brush rake was fitted to the front end 
of the tractor, and a single drum logging winch (sometimes called a 
hoister drum) was mounted on the rear. The logging winch spooled 
several hundred feet of steel cable and operated one or more special 
Ribes hooks light enough to be readily handled by one man. This 
power method was 25 to 50 percent or more cheaper than hand methods 
in heavy Ribes patches. Horse-drawn Ribes plows or hooks were fur- 
ther tested and were shown to be specially well adapted to work on 
open -grown medium-sized bushes of R. cereum and R. roezli. 
Tests of dynamite and of regular grubbing methods on paired 
Ribes bushes showed that substantial savings could be made by the use 
of dynamite on R. cereum bushes having 3,000 or more feet of live stem. 
Dynamite methods were worked out to provide data on the weight 
and the number of charges of 20 percent dynamite needed to uproot 
bushes of various sizes under different soil conditions. 
Regular hand tools were improved through the design of a true claw- 
hammer type of mattock blade which permits the Ribes crown to be 
firmly grasped and then uprooted by a prying technique. Several 
thousand of these new tools were made by relief labor and were used in 
regular crew work. 
A method in which Ribes bushes were marked in advance with white 
mechanic's waste and the marked bushes then destroyed by a crew was 
compared with the established crew method. Statistical analysis of 
field data showed that there was no significant difference between the 
two methods in the total time needed to accomplish initial eradication, 
and that the efficiency of the tagging method as shown by data on niop- 
up time and the number of Ribes missed was less than that of the 
regular method. 
Ecological studies were continued in the sugar pint 1 and western 
white pine regions, and progress was made in compiling data on the 
regeneration of Ribes in relation to fire, logging methods, stand- 
improvement work, slash disposal, grazing, and the various met bod- of 
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