ERADICATING TALL LARKSPUR OX CATTLE RANGES. 



11 



40 acres in July, 1916. An examination in September showed that 

 approximately 75 per cent of the plants had been killed. This low 

 efficiency was due to the fact that the vegetation at the time the 

 grubbing was done was very rank and to a considerable extent had 

 fallen down or been trampled down, thereby making it difficult 

 to locate the smaller larkspur plants. The experience gained in 

 doing the grubbing in 1915 was of material advantage in connec- 

 tion with the work done in 1916, and it is estimated that the 1916 

 work resulted in 90 per cent of the larkspur plants being eradicated. 



It is believed that at least 95 per cent of the plants should be 

 killed by the first grubbing, and that in the practical application of 

 this method one regrubbing, one year after the first grubbing, should 

 be sufficient. A few plants may escape eradication under this plan, 

 and others may originate from seed, but the total number will not 

 be sufficient to cause loss of cattle from poison nor to justify the 

 expense of a third examination and regrubbing. r 



Work 95 per cent effective will not necessarily cost any more per 

 acre than work 85 per cent effective. Care must be exercised, how- 

 ever, to see that each plant is grubbed properly and that small 

 plants are not overlooked. Success can be attained largely by 

 employing reliable workers under proper supervision, especially 

 when the work is being stalled, and by doing the work early in the 

 season, when the larkspur plants show up prominently. 



COST OF GRUBBING. 



The cost of eradication per unit area varies considerably, depend- 

 ing upon the number of larkspur plants and upon the habitat. The 

 cost of grubbing the Stanislaus experimental plots is given in 

 Table 3. 



TABLE 3. Cost of eradicating tall larkspur on experimental plots. Stanislaus 



National Forest. 



Plots 1. 2. 3. and 3A have approximately the same soil and 

 vegetation. They are located in an open weed area having a sandy 



