45 



40 



35 - 



30 - 



25 



20 



15 



10 



5 - 



Competition 



None 



m 



Partial 



Full 



1^ 



No clipping 



Heavy clipping 



Extreme clipping 



Figure 2. Flower stalk production of Idaho fescue the year following 

 clipping under different levels of competition. (The column 

 third from the left represents flower stalk numbers of check 

 plants — no clipping, full competition.) 



data for the undipped plants that were subjected to different 

 competition treatments (figure 3). Undipped plants freed 

 from competition almost tripled their volume in 1 year. Rela- 

 tive volume differences are even more pronounced when the 

 plants are placed under the additional stress of clipping. 

 Plants clipped to an extreme degree and without competition 

 produced nine times more herbage than those subjected to 

 full competition. Interestingly, elimination of competition 

 more than compensated for the very harmful effects of ex- 

 treme clipping. 



The length of Idaho fescue leaves was affected more by 

 differences in dipping intensity than by differences in com- 

 petition (figure 3). Competition alone did not noticeably af- 

 fect leaf length. However, the dual effect of competition and 

 clipping reduced leaf length up to 40 percent. The response 

 of average leaf length to the various treatment combinations 

 closely paralleled that of maximum leaf length. Increased 

 herbage volume that was caused only by reductions in com- 



6 



