RANGE MANAGEMENT ON THE NATIONAL FORESTS. 85 



varies with different plants and for the same plants at different alti- 

 tudes. The time of grazing should be adjusted as far as possible to 

 avoid use of the poison areas during the most dangerous time. The 

 stage of growth at which each of the important species is most dan- 

 gerous to stock is given in the publications listed for reading. 



7. Ample forage suited to the class of stock on a range is an im- 

 portant factor in keeping down loss from poisoning. Lack of more 

 palatable forage results in the stock's eating more of the harmful 

 plants than they ordinarily do where ample nonharmful forage is 

 available. Following the suggestions under the section on determi- 

 nation of the class of stock to which a range is best suited will aid 

 in overcoming this difficulty. 



Departures from the practice outlined in these suggestions are not 

 uncommon and are responsible for the annual loss of large numbers 

 of stock. 



Of approximately 6,000 cattle lost annually from poisonous plants 

 within the National Forests, it is estimated that about 90 per cent are 

 killed by tall larkspur. 1 The heaviest losses usually occur on small 

 portions of the ranges. A hundred acres or less of tall larkspur 

 within a cattle range unit of 15,000 acres may be responsible for an 

 annual loss of stock great enough to discourage stockmen in the use 

 of the range. Range, however, is valuable, and heavy expenditures 

 on the small infested areas are warranted, if, as a result, an entire 

 range unit can be made safe for cattle grazing. 



During the years 1915-1917 tall larkspur was grubbed out on large 

 cattle range units within 16 National Forests. A total of over 1,900 

 acres of larkspur was grubbed out at a total cost of approximately 

 $11,000. By this expenditure more than a quarter of a million acres 

 of cattle range has been freed entirely from loss of stock by larkspur 

 poisoning, or the losses have been reduced to an occasional animal. 

 The cattle saved in 1917, as a result of the grubbing work on 9 out of 

 the 16 Forests for which reliable figures are available, were valued at 

 nearly $16,000. The reduction in loss on the other seven Forests was 

 considered equally satisfactory, but no actual figures are available. 



The cost of grubbing per acre of larkspur has varied from $2.69 to 

 about $13, depending upon the number of larkspur plants per acre, 

 the amount of rock and gravel in the soil, whether the larkspur was 

 growing in willows or brush, and the cost of getting men and supplies 

 to the work. Whether the grubbing of tall larkspur from a given 

 cattle range unit is warranted, however, depends upon the possible 

 reduction of loss in cattle annually as compared with the total cost of 

 grubbing and not upon the cost of grubbing per acre of larkspur. 



1 Aldous, A. E., Eradicating Tall Larkspur on Cattle Ranges in National Forests, U. S. 

 Dept. of Agriculture, Farmers' Bui. 826, 1917. 



