HERBICIDES IN PLANTS 
W. C. Shaw, J. L. Hilton, D. E. Moreland, and L. L. Jansen’! 
The native vegetation in most geographical areas in the United States was not very 
eilicient or economical as a source of food for livestock and humans, As the human 
population has increased, it has beennecessary to replace the native vegetation with more 
productive, more efficient, and more economical plants for food and fiber (figure 1). 
FOOD PRODUCTIVITY POTENTIAL 
CLIMAX wOODY PERENNIAL ANNUAL LOW VALUE HIGH VALUE 
VEGETATION SHRUBS GRASSES AND WEEDS CROPS CROPS 
WEEDS 
VEGETATIVE COMPOSITION 
SCIENTIFIC TECHNOLOGY —————> 
<< NATURAL SUCCESSION 
BN-10805-X 
Figure 1 
The sequence of events that occurs in plant successions when native vegetation is 
disturbed or cultivated fields are abandoned is wellknown. Weeds comprise an early stage 
of plant successions that terminate with the climax-vegetation characteristic of the area, 
One of the basic objectives ofagricultural researchis to develop more efficient plants 
and soils and to manage them at high productivity levels. The fundamentals of plant 
ecology emphasize that plant successions always occur in the direction of the climax- 
vegetation rather than toward the growth of more productive economic crop plants. 
In our efforts to produce economic crops, we attempt to utilize fully all available 
scientific technology to stabilize the vegetation at a highly productive level. The control 
of weeds is a basic, essential, and important aspect of this fundamental ecological 
process (figure 1), 
1Plant Physiologists, respectively, Crops Research Division, Agricultural Research Service, U. S, Department of Agriculture, at 
Beltsville, Md,, and Raleigh, N, C. 
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