the disease goes through part of its lite cycle, and so back 

 to pine. Thus, the spread of the infection follows a series 

 of circles, and so long as these remain unbroken the 

 disease cannot be halted. 



The spread from pine to ribes may range over 100 or 

 150 miles, but that from ribes to pine must be within about 

 1,000 feet. Consequently, the control has attempted to 

 break the circle of development by eliminating as many ot 

 the ribes as practicable from western white pine lands, 

 especially from young Stands. Since wild currant and 

 gooseberry plants are prominent components ot the western 

 white pine type, this is a task to stagger the imagination. 



Between 1923 and 1939, more than 351 million ot these 

 plants were uprooted by hand. This is the principal 

 means of eradication (fig. 37), although several other 

 methods have been developed to meet special conditions. 

 By all methods combined, the eradication program had 

 covered, by Januarv 1940, 1.6 million acres ot western 

 white pine land in northern Idaho. Because of particu- 

 larly heavy occurrence ot ribes on some lands, 229,000 

 acres have had to be worked twice and 19,000 acres three 

 times to secure adequate control. The Office of Blister 

 Rust Control ot the Bureau of Entomology and Plant 

 Quarantine and the Forest Service estimate that protection 

 can be (ustified on 0.7 million acres as yet unworked, on 

 which, pathologists point out, the disease is advancing 

 rapidly. In addition, a portion ot the area already treated 

 will have to be reworked before adequate control will be 

 established. 



It should not be assumed that the completion ot this 

 program will be the final chapter in blister rust control. 

 The attempt to eliminate the ribes completely is rendered 

 futile, for one thing, by the longevity ot ribes seed. Evi- 

 dence indicates that wild currant and gooseberry seed, 

 under proper conditions, may retain their germinability 

 for more than a century. The opening ot a stand and the 

 disturbance ot the forest floor by logging, fire, or other 

 cause induces this dormant seed to germinate and establish 

 a new crop ot ribes. The problem, theretore, is one ot 

 reducing the ribes population to the point where western 

 white pine can be grown commercially on western white 

 pine areas, and then keeping it there by turther control as 

 required. 



Control Costs 



Covering the 1.6 million acres already worked foot by 

 foot has been a big and expensive job, which can be 

 justified only because the value of the western white pine 

 timber jeopardized is large. It is estimated that from 1922 

 through 1939, in all ot the projects related to blister rust 

 control work in northern Idaho, $8,859,000 was spent. 

 Besides actual eradication, this includes research, quaran- 

 tine work and surveys. By and large, it has been publicly 



BR-8130 



FiGL'KE 37. — J hig job — 351,000,000 ribes plants have been pulled out by 

 hand, as recorded photographically in this instance by the Bureau of 

 Entomology and Plant Quarantine. 



financed, the greater part ot it under the various emergency 

 reliet work projects, as the following tabulation shows: 



Regular funds. U. S. Bureau of Entomology and Plant 



Quarantine (1922-39) ?1,1 11,000 



Regular funds. U. S. Forest Service (1930-39) 1,798,000 



Public Works Administration (1933-34) 1,840,000 



Work Projects .'Administration (1935-39) 3,038,000 



Civilian Conservation Corps (1933-39) 862,000 



State and Private (1928-39) 210,000 



Total 8,859,000 



It has been estimated by the Bureau of Entomology and 

 Plant Quarantine and the Forest Service that approxi- 

 mately 9.7 million dollars more will be required through 

 1948 to complete the control work in northern Idaho and 

 place it on a maintenance basis, or, for the western white 

 pine area as a whole, $8 per acre, as follows: 



Past expenditures in northern Idaho f8,900,000 



Proposed necessary expenditures 9,700,000 



Total 18,600,000 



Per acre on 2.3 million acres 8.00 



This is the expenditure necessary to establish control ot 

 the disease on areas now containing stands of western white 

 pine of all age classes, and on such new areas as may come 

 into western white pine by 1948. The subsequent main- 

 tenance ot control will be primarily a reworking ot areas 

 cut over or burned over after 1948, on which western white 

 pine germination takes place. A certain amount of rework 

 will also be required along stream bottoms where the ribes 

 were particularly thick and are persistent. Naturally the 

 maintenance costs will vary from year to year depending 

 upon the extent of fires and logging. Any estimate ot 

 these maintenance costs contains a large element of con- 



38 



