Cultural, mechanical, biological, and chemical methods of weed control have been 
used for centuries. In recent years, herbicides have demonstrated outstanding potential 
for the selective control of weeds in crop production. If maximum benefits are to be 
realized from this vast, versatile, efficient, and economical source of energy for the 
control of weeds, we must develop a fundamental knowledge of the effects of herbicides 
on plants, soils, animals, and humans. The fate of herbicides in plants then becomes a 
critically important aspect of chemical weed control, It is an additional dimension in 
weed control research which must be better understood if we are to realize maximum 
benefits from the use of herbicidal chemicals. 
The purpose of this paper is to review some of the progress that has been made in 
determining the fate of herbicides in plants and to indicate some of the problems needing 
additional emphasis for maximum, efficient, and safe use of herbicides for weed control 
in crops. 
In the time allotted it would be impossible to discuss all the research that has been 
reported in the literature on the fate of herbicides in plants. For this reason, we have 
chosen a series of slides to illustrate some of the progress that has been made and to 
discuss certain principles that have been developed from research on the penetration, 
absorption, translocation, mechanisms and sites of action, and metabolism of herbicides 
in plants. 
The fate of herbicides in plants is determined by morphological characteristics, 
physiological processes, and biochemical properties of the protoplasm of plants as 
influenced by environmental factors that affect growth. 
MORPHOLOGICAL CHARACTERISTICS WHICH INFLUENCE 
DISTRIBUTION, RETENTION, AND UPTAKE OF HERBICIDES 
Plant form, leaf shape, leaf position, leaf density, leaf surface, and leaf margins 
greatly influence the foliar distribution, retention, and uptake of herbicides (figure 2), 
MORPHOLOGICAL CHARACTERISTICS 
WHICH INFLUENCE DISTRIBUTION, 
RETENTION, AND UPTAKE OF HERBICIDES 
Seer PLANT FORM 
PONG A E t 
pa 7 Spreaging 
i, ¥ Prostrate 
EEA. SHARE 
COTTON Broad, large 
Narrow, short or linear : 
lees Rae LEAF POSITION AND DENSITY CORN 
NV Horizontal 
My Upright or pendulous 
Y FLax LEAF SURFACE AND MARGINS 
Ww 
Hairy AP 
Various sculpturing \, 
B® ( ‘ 
x ys | 
— hf \ SMALL GRAIN 
i PEANUT ‘y ZN Ss VERVE ree | 
Gi SOYBEAN | ee / WILD ONION 
DICOTS Xe Le MONOCOTS 
BN-10802-X 
Figure 2 
120 
