possesses herbicidal properties similar to those of IPC, In contrast to IPC, N-hydroxy- 
IPC was active when applied to the foliage of oats, It has been suggested that IPC may be 
biologically oxidized within the plant to N-hydroxy-IPC. This was considered to be an 
activation reaction (4). 
Ethyl N,N-di-n-propylthiolcarbamate [EPTC] is readily absorbed by plants from 
soil. Kidney beans, sweet corn, garden peas, radishes, carrots, cabbage, mustard, table 
beets, and sugar beets were treated with S35-labeled EPTC. The largest amount of free 
EPTC-S35 remaining in the tissues several weeks after treatment was less than 3 percent 
of the total amount absorbed (19). 
In relatively short-term experiments, the amount of EPTC-S*° decreased with time 
in resistant seedlings but no decrease was observed in susceptible species (20). Identi- 
fication of radioactive compounds obtained from treated plants suggested that the sulfur 
atom was oxidized to sulfate. The sulfate was then incorporated into normal sulfur-con- 
taining metabolites including cysteic acid, cystine, methionine, methionine-sulfone, and 
two unidentified compounds, 
Amitrole 
Much of the information concerning the metabolism of 3-amino-1,2,4-triazole 
[amitrole] in plants is unpublished or available only in abstract form. Nevertheless, the 
published evidence indicates that amitrole is metabolized by plants (1,10,33,40,45,46,47, 
69). The rate of metabolism and the biochemical reactions involved vary according to 
species (33,47,69). If any metabolized form of C!4-labeled amitrole is formed in corn, 
it is not accumulated by the plant. Soybeans, however, accumulate a Cl4-labeled ami- 
trole-metabolite at the expense of unaltered amitrole. Degradationof the herbicide in both 
species is suggested by the steady decrease in radioactivity that occurs during a 3-week 
period (69). 
Various species of legumes rapidly metabolize amitrole. ee 7 percent of the radio- 
activity recovered from pinto beans 5 daysaftertreatment with C!4-labeled amitrole was 
still in the form of the original molecule (45). As much as 2mg.of metabolite per plant 
has been obtained from French dwarf bean 5to 7 days after treatment (40). The amitrole- 
metabolites accumulated by various species of legumes seem to contain the same ring 
system and free amino group of the parent molecule plus an additional component 
(10,40,45). Radioactivity from C14-labeled glycine or serine was incorporated into the 
amitrole-metabolite accumulated by Phaseolus vulgaris var, Black Valentine (10). The 
chemical properties of the major metabolite obtained from pinto beans suggested that the 
compound had an amino acid-like structure (45). The amitrole-metabolite from French 
dwarf bean was identified as 3-amino-1,2,4-triazolyl alanine,a-Alanine was obtained from 
this metabolite by chemical degradation (40), 
Compound X and compound Y, the major and minor amitrole-metabolites recovered 
from pinto beans, were compared with amitrole for toxicity against duckweed (45). Com- 
pound X was not metabolized by duckweed, It caused some chlorosis and stunting but was 
not as toxic as the parent herbicide. Compound Y did not appear to be toxic. The formation 
of these compounds may, therefore, represent detoxification mechanisms which may or 
may not be a result of the toxic action of amitrole. 
Amitrole reacts with glucose in vitro (28), and this compound is sometimes found in 
extracts from plant materials (33,46), The earliest report recognized that the compound 
might not be of metabolic origin (47).Ifthe glucose complex is formed in amitrole-treated 
plants, it appears to be metabolized by the plant (55) and to serve as a substrate for 
hexokinase (28). 
CDAA 
Resistant crop seedlings such as soybeans and corn absorb 2-chloro-N,N,-diallyl- 
acetamide [CDAA] and completely metabolize it within 4 to 5 days after emerging from 
the soil. Glyoxylic acid is one of the earliest degradation products identified in the plant. 
127 
