Note: Descriptions are shown in the official language in which they were submitted.
210~99 ~ `
wo 92/16101 PCT¦EP92/00506
FILE, UN~N THiS AM~NDED
Description l~E~ TRANSLATION
Maize resistant to aryloxyphenoxyalkanecarboxylic acid
herbicides
Aryloxyphenoxyalkanecarboxylic acid herbicide~ ~which are
also to be understood as meaning heteroaryloxyphenoxy-
alkanecarboxylic acid derivatives) are effective grass
herbicides. A representative of this class of active
sub~tances which i8 to be mentioned hereinafter is
fenoxaprop-ethyl ("FOPE"), which is to be understood as
meaning the biologically active D-isomer as well as the
racemate. They act on plants from the family of the
Poaceae (Gramineae), since only this plant family have a
specific form of acetyl coenzyme A carboxylase (ACC)
which can be inhibited by micromolar concentrations of
FOPE. Remaining terreetrial plants have ACC types whose
~ensitivity to this clas~ of active substances is 100 to
1000 times lower.
Since FOPE and other aryloxyphenoxyalkanecarboxylic acid
herbicides are taken up via the aerial part6 of the
plant~, but are rapidly inactivated in the 80il, these
herbicides are suitable for controlling grasses post-
emergence.
"
; The crop plant maize (Zea mays) is particularly ~ensitive
; to FOPE. This is why these compounds cannot be used for
2s controlling grass weeds in maize fields.
~; It has been found that in areas where FOPE ha~ been
applied repeatedly, forms arise spontaneously in popu-
~; iations of wild grasses ;hich are resistant to this class
of herbicide. Since such mutations occur only at a rate
`~ ~ 30 of approximately 10-9 to 10-9, a corre~ponding search for
mutants in maize fie~d~ would be of little promise even
- i if maize were not so highly sensitive to FOPE.
:
~ Surprisingly, it has now been found that maize cells can
.
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21~990
be selected which are resistant to FOPE and which can be
grown on to give resistant plants which, in turn, pass on
thi~ resistance property in a stable manner.
Cell lines which are ~uitable for selection are known
(for example from Morocz et al., Theor. Appl. Genet. ~o
(1990) 721-726) or have been propo6ed in European Patent
Applications 90 111 945.3 and 90 111 946.1. With effect
from September 30, 1990, a s,uitable cell line was depo-
sited at the Deutsche Sammlung von Mikroorganismen und
Zellkulturen ~German Collection of Microorganisms and
Cell Cultures] in compliance with the provi~ion of the
Budapest treaty, Deposit No. DSM 6009.
To obtain resistant cell lines, the cells are cultured in
auxin-free media in the presence of FOPE concentrations
which kill more than 90% of the cell~. The cells can be
cultured in such media for as long as desired, for
example easily over 10 transfers and more. Synthetic
auxins, such as 2,4-dichlorophenoxyacetic acid, p-chloro-
phenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid and
3,6-dichloro-2-methoxybenzoic acid (dicamba) antagonize
the effect of FOPE if the latter ie employed in sublethal
concentrations. Selection experiments using FOPE in the
concentration range of up to 105 M in the presence of
synthetic auxins were un~uccessful. This is why auxin-
autotrophic maize cell lines were used.
It is characteristic of auxin-autotrophic cell lines that
they can, in the form of an embryogenic culture, be
subcultured on phytohormone-free cell culture media for
: a~ long a~ desired, for example for two to three years.
Auxin autotrophic calli were subcultured in each case
every 3 to 4 weeks over 15 transfers and more, and
mutants were found by stepwise increase of the FOPE
concentration. The~e FOPE-tolerant mutants can be sub-
cultured over 10 tran~fers and more on FOPE-containing,
auxin-free medium. Under selective conditions, i.e. in
the presence of 10-~ M FOPE, the embryogenic calli
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`` 21059~0
~ 3 -
spontaneously give rise to plants which can be grown on
to give fertile maize plants.
Flowering regenerated plants are, on the one hand, selfed
and, on the other hand, pollen from the regenerated
plants i9 used for pollinating inbred lines. The mature
seeds are sown, and the Fl generation seedlings are
treated with FOPE when they have reached the 2- to 4-leaf
stage. A considerable number of selected plants survive
even at concentrations of up to 200 g of active substance
per ha (g of a.i./ha).
The regenerated maize plants can be treated with FOPE at
rates of up to 200 g of a.i./ha; it i9 preferred to
employ betwéen 20 and 150 g, in particular between 30 and
90 g, of a.i.tha. These amounts apply to the biologically
active D-isomer of fenoxaprop-ethyl. Maize plants accor-
ding to the invention are preferably selected using the
optically active isomer, but suitable amounts of the
racemate can also be employed.
The ACC gene can be isolated from the mutants according
~0 to the invention and characterized in a manner known per
se. Mutated genes, which encode FOPE-tolerant ACC, can be
used for the transformation of other plant cells.
It is furthermore possible to combine FOPE tolerance in
maize with resistance to other herbicides. To this end,
for example, transgenic cell lines are use~ which contain
a resistance gene for the non-selective herbicide phos-
phinothricin, glufosinate or bialaphos. Such genes are
disclojsed, for example, in EP-A 0,257,S42, 0,275,957,
0,297,618 or from DE-A 3,701,623 or DE-B 3,825,507. When
~uitable cell lines are grown, phosphinothricin tolerance
~an be employed as an additional marker.
Otper tran~genlc plants according to the invention may
contain toxin gene~, for example genes encoding the
~-endotoxin of Bacillus thuringiensis, or genes for
: . ., : ~ - , . . .
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... . , , .: .. .. .. . . .
.. , . . : - '.: . :.. : . . .
- 2 1 ~ c) ~ 9 0
chitinases or glucanase~, or other selectable marker
genes, for example genes for resistance to glyphosate or
sulfonylureas.
The following (C~-C4) alkyl, (C2-C4)alkenyl and (C3-C~) -
alkynyl aryloxyphenoxyal~anecarboxylate herbicides can
also be employed for selecting resistant maize cell
lines:
Al) Phenoxyphenoxy- and benzyloxyphenoxyalkanecarboxylic
acid derivatives, for example
methyl 2-(4-(2,4-dichlorophenoxy)phenoxy)propionate
(diclofop-methyl),
methyl 2-(4-(4-bromo-2-chlorophenoxy)phenoxy)propionate
(see DE-A-2,601,548),
methyl 2-(4-(4-bromo-2-fluorophenoxy)phenoxy)propionate
(~ee US-A-4,808,750),
methyl 2-(4-(2-chloro-4-trifluoromethylphenoxy)phenoxy)-
propionate ~see DE-A-2,433,067),
me,thyl 2-(4-(2-fluoro-4-trifluoromethylphenoxy)phenoxy)-
propionate (see US-A-4,80B,750),
methyl 2-(4-(2,4-dichlorobenzyl)phenoxy)propionate
(see DE-A-2,417,487),
ethyl 4-(4-(4-trifluoromethylphenoxy)phenoxy)pent-
2-enoate,
methyl 2-~4-(4-trifluoromethylphenoxy)phenoxy)propionate
(~ee DE-A-2,433,067),
A2) "Mononuclear" heteroaryloxyphenoxyalkanecarboxylic
acid deri~atives, for example
ethyl 2-(4-(3,5-dichloropyridyl-2-oxy)phenoxy)propionate
~see EP-A-2,925),
propargyl 2-(4-(3,5-dichloropyridyl-2-oxy)phenoxy)-
propionate (EP-A-3,114),
methyl 2-(4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)-
phenoxypropionate (see EP-A-3,890),
ethyl 2-(4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)-
phenoxy)propionate (see EP-A-3,890),
propargyl 2-(4-(5-chloro-3-fluoro-2-pyridyloxy)phenoxy)-
- - - -: -: . :
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-- 5
propionate (EP-A-191,736),
butyl 2-(4-(5-trifluoromethyl-2-pyridyloxy)phenoxy-
propionate (fluazifop-butyl; fusilade-butyl),
A3) ~Binuclear~ heteroaryloxyphenoxyalkanecarboxylic acid
derivatives, for example
methyl and ethyl 2-(4-(6-chloro-2-quinoxalyloxy)-
phenoxy)propionate (quizalofop-methyl and -ethyl),
methyl 2-(4-(6-fluoro-2-quinoxalyloxy)phenoxy)propionate
(see J. Pest. Sci. Vol. 10, 61 (1985)),
methyl and 2-isopropylideneaminooxyethyl 2-(4-(6-chloro-
2-quinolyloxy)phenoxy)propionate (propaquizafop and it~
ester),
ethyl 2-(4-(6-chlorobenzoxazol-2-yloxy)phenoxy)propionate
(fenoxaprop-ethyl) and
ethyl 2-(4-(6-chlorobenzothiazol-2-yloxy)phenoxy-
propionate (see DE-A-2,640,730)).
The auxin-autotrophic cell lines are also particularly
suitable for the selection of mutants which are obtained
using other ACC-inhibitors, namely cyclohexanedione-
herbicides, in particular sethoxydim, tralkoxydim,
cycloxydim, alloxydim and clethoxydim.
The fact that maize plants can be obtained which are
re~istant to conventional concentrations of sethoxydim
has been published by Parker et al. (Proc. Natl. Acad.
Sci. Vol. a7, pp. 7175-7179). These plants also display
a certain cross-resistance to low concentrations of
haloxyfop. ~owever, the maize~plants produced according
to the invention are resistant to higher concentrations
of aryloxyphenoxyalkanecarboxylic acid herbicides, as
30, they are required for use in practice. Thus, the maize
plants according to the invention allow the selective
control of monocotyledon weeds (grass weeds) in maize
using aryloxyphenoxyalkanecarboxylic acid derivatives
(including heteroaryloxyphenoxyalkanecarboxylic acid
derivatives), either alone or in combination with each
other.
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-- 6
The invention also relates to the use of maize plants
which are treated with a combination of aryloxyphenoxy-
carboxylic acid herbicides and herbicides against dicoty-
ledon weeds. Thi~ i~ because it was possible, surpris-
ingly, to identify components for mixtures for aryloxy-
phenoxyalkanecarboxylic acid herbicides which are not
only tolerated by the regenerated maize plants, but whose
herbicidal activity is simultaneously improved.
Thus, the combination of the herbicides results in syner-
gistic effects. Using such mixtures means substantialeconomical, but also ecological, advantages.
Synergism is to be understood as meaning a mutually
reinforcing effect of two or even more substances. In the
, present case, the combined use of two herbicides allows
the application rate of the herbicides to be reduced
while still achieving the same herbicidal activity, or,
using the same application rates of the herbicides allows
a higher activity to be achieved than to be expected on
the ba~is of the individually employed active substances.
By using such synergistic effects, it is possible to
considerably reduce the application rates of the com-
ponent~ involved in the mixture, and a broad range of
mono- and dicotyledon weeds can be controlled in one
operation. The reduced application rates apply in parti-
cular to the ACC-inhibitors, but also to the components
in the mixtures with regard to effectiveness against
dicotyledon weeds.
Particularly interesting from amongst the aryloxyph~noxy-
alkanecarboxylic acid herbicides are the following
3~ herbicides: fenoxaprop-ethyl, haloxyfop-methyl,
quizalofop-ethyl, fluazifop-butyl.
The following herbicide~ display synergi~tic activity
when used as a component in mixtures for the additional
control of broad-leaf weeds;
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210~99~
Primisulfuron, thifensulfuron, nicosulfuron, DPX-E 9636,
amidosulfuron, pyridylsulfonylureas, as described in
German Patent Applications P 4,000,503.8 and
P 4,030,577.5, in particular 3-(4,6-dimethoxypyrimidin-
2-yl)-1-13-(N-methyl-N-methylsulfonylamino-2-pyridyl-
sulfonyl]urea, an alkoxyphenoxysulfonylurea, as described
in EP-A-0,342,569, furthèrmore NC 319 (EP 2~2,613) and
other sulfonylureas, as well as mixtures of various
abovementioned sulfonylureas with each other, ~uch as,
for example, a mixture of nicosulfuron and DPX-E 9636.
Other herbicides which have the same, or a similar,
mechanism of action as the above sulfonylureas, namely
imidazolinones, such as, for example, imazethapyr, imaza-
quin, imazapyr (each of which can be employed in maize
together with a safener), also display a synergistic
increase in activity when employed together with ACC
inhibitors.
Other herbicides which, like ~ulfonylureas and imidazoli-
nones, are inhibitors of the enzyme acetolactate synthase
(ALS) are also suitable, for example substituted pyrimi-
" dines and triazines, herbicidal ~ulfonamides, such as
flumetsulam (Cordes, R.C. et al., Abstr. Meet. Weed Sci.
Soc. Am. 31, 10, 1991), or other related compounds and
mixtures of euch active substances with each other.
A series of other herbicides which are employed for
controlling weeds in maize, but display different mecha-
nisms of action, also showed a synergistic increase in
activity when used together with fenoxaprop-ethyl or with
other ACC inhibitors:
ICI-051: (2-12-chloro-4-(methylsulfonyl)be,nzoyl]-1,3-
cyclohexanedione, atrazine, cyanazine and terbuthylazine,
clopyralid, pyridate, bromoxynil, pendimethalin, dicamba.
The hérbi~ides are generally u~ed at application rates of
between 0.01 and 2 kg/ha, i.e. the total amount of active
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sulbstance combination to be used is approximately 0.05 to
2 kg/ha. The application rate required can vary as a
function of the external conditions, such as temperature
and humidity, inter alia, that is preferably between 0.05
and 1 kg/ha. The ratios of t~e components can vary within
wide limit~. A quantitative ratio of between 1:20 and
20:1 is preferably selected.
These synergistic effects are achieved not only in the
case of mixtures with fenoxaprop-ethyl, but also when
other ACC inhibitors are used, for example the cyclo-
hexanediones. A combination of the active substances is
t~o be understood as meaning that the herbicidal active
substances are applied together or one after the other,
at an interval of a few day~, in the form of a so-called
split application. In each case the weeds respond with an
increased sensitivity, 80 that lower application rates
allow a very good control effect.
In the ollowing examples, the invention will ~e illus-
trated in greater detail without being restricted
thereto. Percentages relate to the weight, unless other-
wise specified.
1st Example : Selection of FOPE-tolerant embryogenic
maize cell cultures
Maize plants from inbred lines B 73 and LH 82 were
pollinated with pollen from genotype HE 89, which is
capable of regeneration (Morocz et al., Theor. Appl.
Genet. 80 [1990) 721-726 loc. cit.). 12 to 14 days after
pol~ination, immature embryos were dissected from the
seeds under sterile conditions and grown on hormone-free
N6 culture medium (Chu et al., Sci. Sin. 18 (1975)
659-668) containing 9~ of sucrose, the embryo axis being
in contact with the medium. Within 3 to 4 weeks, embryo-
genic callu~ waQ formed on approximately 25% of the
embryos, 1.0 to 2.0 mm in size, and this embryogenic
callus could be subcultured on hormone-free medium. After
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210~9~0
g
3 to 4 subcultures, the selection of FOPE-tolerant
mutants wa~ started using the callus lines which were
distinguished by vigorous growth and reproducible diffe-
rentiation of somatic embryos on the hormone-free medium.
Alternatively, callus lines were cultured, with 3 to 4
transfers, on N6 medium containing 1 mg/l of 2,4-di-
chlorophenoxyacetic acid (2,4D). The callus sectors
con~isting of undifferentiated cells were used for
subculturing. From these callus sectors, suspension
cultures could be induced which were cultured in liquid
N6 medium containing 0.5 mg/l of 2,4D and transferred
weekly to fresh medium.
Tissue was taken from both callus cultures and suspension
cultures and incubated for 4 to 6 weeks on hormone-free
N6 medium in the presence of 1-3 x 1 o-6 M FOPE. Under
these conditions, up to approximately 95 ~ of the cells
and cell cluster~ were killed
The surviying cell clusters were grown on on hormone-free
N6 medium containing 3 x 10-6 M FOPE, by means of 2
passes. Per tran~fer, the cell~ remained on the selection
medium for 4 to 6 weeks.
Subclones growing equally well under these conditions as
wild-type cells on FOPE-free medium were grown on on
hormone-free N6 medium containing 1 x 105 M FOPE.
After a further 4 to 6 weeks, those clones which con-
tinued to grow on this selection medium without signifi-
cant loss of vitality were transferred to a medium
containing 3 x 105 M FOPE and, during the following
subculturing, transferred to hormone-free N6 medium
containing 1 x 10-~ M active sub3tance. Higher active
sub~tance concentrations did not improve the selection
effect further since the active substance crystallize~ in
, the medium at a concentration of as little as 3 x 10-5 M.
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Example 2: Regeneration of FOPE-tolerant plants
Plants which have been regenerated from those mutated
clones which grew in the presence of 1 x 10-~ N FOPE in
hormone-free N6 medium for 3 to 10 transfere without
reduced vitality, differentiating plants fro~ somatic
embryos in the process, were transferred into soil and
grown in a controlled-environment cabinet at 30,000 to
40,000 Lux, a daytime temperature of 23 i 1C and a
night-time temperature of 16 ~ 1C, with an illumination
period of 14 houre. When the plants have developed 4 to
5 leaves, they are sprayed with 30 g of FOPE per ha. The
plants survived this treatment without significant
damage, while control plants were killed by the herbicide
at this dosage rate.
Th~ flowering regenerated plants were, on the one hand,
selfed and, on the other hand, their pollen wa~ ueed for
pollinating inbred lines, such as, for example, B 73,
LH 51, LH 82, LH 119, KW 1292, KW 5361, RA 129B or
RA 3080. The mature seeds were sown, and the Fl gene-
20~ ration seedlinge treated with FOPE when they had reachedthe 2- to 4-leaf stage. The resulte are giYen in Table l.
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Table 1: Treatment of regenerated plants and progeny
with FOPE (* und. = undamaged)
Plants Number , FOPE treatment
15 g of 30 9 of 60 9 o~
a.i./ha a.i./ha a.i./ha
dead dead dead
plantstund.* plants/und.* plants/und.*
Regen. 20 20
plants of
unselected
controls
Regen. 10 - 10
plants of
resistant
callus
Progeny from 60 5 15 7 13 8 12
self-pollin-
ation (3X20)
F,-progeny 48 8 8 10 6 7 9
from
crosses ~3X16)
Commercial 48 16 - 16 - 16
variety
Felix
: ~ Example 3: Haloxyfop-tolerant maize
Resi'stant maize cell lines were obtained by the process
described in Examples 1 and 2 and examined for resistance
to haloxyfop. It was found that cell lines according to
the invention tolerate a markedly higher dosage rate than
the maize cell lines known from the prior art (see Parker
et al.)..
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Example 4: Treatment of herbicide-resistant maize plants
with synergistic combinations of herbicides
FOPE-resistant maize plants obtained by the process
described in Examples 1 and 2 were grown in the green-
house in pots of diameter 9 cm together with grass weedsand broad-leaf weeds until they had reached the 4-6 leaf
stage, when they were treated post-emergence with the
herbicides according to the invention. A water volume of
400 l/ha were used, two replications were carried out,
and, after 5 weeks, the plants were scored on a percent-
age key basis by visually assessing the control effect on
the weeds.
The results from various experiments showed unexpected
~ynergistic increases in effects by herbicidal combi-
nations which had been applied either concomitantly orone shortly after the other (see Tables 2 and 3).
No damage of any kind wa6 observed on the herbicide-
resistant maize plants. Herbicides B4 and B6 was in each
case both applied together with an active ~ubstance which
acts as a safener.
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Table 2: Herbicidal activity against grasses
. . - __ ... _ .
Herbicide Dosage rate of . % activity against
¦ . g of AS/ha SEVI DISA PAMI ECCG SOHA ZEMA
I .. __ .. _
A 50 100 100 0
100 99 100 100 98 0
12 85 85 100 100 85 0
6 60 S0 80 99 40 0
Bl 50 98 93 65 98 60 0
0
12 85 75 10 80 25 0
_
1 B2 12 0 10 0 0 20 0
6 0 5 0 0 0 0
...
B3 50 50 20 30 30 90 0
0 20 80 0
12 30 0 0 20 70 0
...... __ .
B4 25 80 90 . 65 95 45 0
" I 12 70 85 40 90 30 0
6 60 70 15 75 20 0
B5 25 85 95 70 90 70 0
12 80 90 40 80 50 0
6 80 80 25 70 30 0
..
I B6 100 95 90 70 70 60 0
0
~ .
¦ B7 250 5 0 0 10 0 0
I 125 0 0 0 0 0 0
' '............. .... ... _ ~ _,
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.... ~ _ . ,, ~ . ,
Herbicide Dosage rate of% activity against
¦ g of AS/haSEVI DISA PAMI ECCG SOHA ZEMA
" B8 250 0, 0 0 0 0 0
125 _ 0 0 0 0 _ 0 0
B9 250 0 0 0 5 0 0
125_ 0 0 0 0 0 0
A + Bl 12 + 12 100 100 100 100 98 0
12 + 25 100 98 95 lO0 80 0
I
A + B2 12 + 12 100 100 100 100 99 0
' 6 + 12 __ _ 100 99 100 100 75 0
_
A + B3 12 + 12 100 100 100 lO0 100 0
12 + 25 100 100 100 100 100 0
I ,
A + B4 12 + 12 100 100 100 100 99 0
6 + 6 100 95 95 100 90 0
A + B5 12 + 12 100 100 100 100 100 0
6 + 6 100 98 98 100 100 0
I . . ._._,
A + B6 12 + 50 100 100 100 100 100 0
1 6 + 25 100 99 98 100 95 0
¦ A + B712 + 125 95 90 100 100 95 0
A + B812 + 125 90 95 100 99 90 0
I .
¦ ~ + B912 + 125 95 90 99 99 90 0
. : .. .
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2105990
- 15 -
_ .
¦ Herbicide Dosage rate of
¦ g of AS/ha ABTH CHAL AMAR POCO AMRE ZEMA
I .. ..
¦ A 50 0 0 0 0 5 0
0 0 0 0 0 0
12 0 0 0 0 0 0
1 6 0 0 0 0 0 0
I _ ..
Bl 50 20 35 20 50 60 0
S0 0
12 0 10 0 10 50 0
¦ B2 12 40 80 70 80 20 0
, 1 6 20 60 40 50 10 0
I B3 . 50 70 80 30 40 40 0
0
12 _ 40 50 020 _ 15 0
B4 25 20 95 85 80 80 0
12 10 85 80 70 75 0
6 0 50 70 70 60 0
____
Bg 25 30 80 75 30 60 0
12 20 60 60 20 50 0
6 10 40 40 10 30 0
B6 100 60 40 70 50 80 0
_ _ _ 50 50 30 60 40 7o-- 0
B7 250 40 100 75 80 75 0
125 ~ 15 85 40 50 30 O
~ . ` . .
: ,,, ~ , : ~ , , . ,, ., ,,, `, ,., ` , .
.. . ,.,.. ,.~:, . `. ` : ` ` -
. ~ , , ` `
9 9 ~
- 16 -
. __ __ ~
¦ Herbicide Dosage rate of .
¦ g of AS/h~ A8TH CHAL AMAR POCO AMRE ZEMA
B8 250 70 95 70 85 65 0
125 30 75 30 60 30 0
¦ B9 250 90 100 98 80 75 0
1 125 75 80 70 40 60 0
I .__ _ ..
¦ A + Bl 12 + 12 40 50 30 60 90 0
1 12 + 25 40 30 30 40 75 0
¦ A + B2 12 + 12 70 90 80 95 40 0
1 6 + 12 60 80 75 90 40 0 ~:
¦ A + B3 12 + 12 60 70 30 50 30 0
12 + 25 70 80 40 50 40 0
A + B4 12 + 12 50 95 90 90 80 0
6 + 6 30 60 60 90 75 0
A + B5 12 + 12 50 90 95 40 90 0
6 + 6 40 75 50 30 60 0
ll ~... l
A + B6 12 ~ 50 70 50 95 70 80 0
6 + 25 50 30 60 40 60 0
A + B7 12 + 125 40 90 50 70 50 0
A + B8 12 + 125 60 80 40 60 40 0
.
A ~ B9 lZ ~ 125 90 90 80 50 60 0
. :......... ., ~ - ;
: . . . . . .. - ~ .
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210~990
, - 17 -
Key for Tables 2 and 3:
SEVI = Setaria viridis (green foxtail)
DISA = Digitaria sanguinali (large crab grass)
PAMI = Panicum miliaceum (proso millet)
ECCG = Echinochloa crus galli (common barnyard grass)
SOHA = Sorghum halepense (Johnson grass)
ABTH = Abutilon theophrasti (velvetleaf)
CHAL = Chenopodium album (pigweed)
AMAR = Ambrosia artemisifolia (hogweed)
POCO = Polygonum convolvulus (black bindweed)
A~RE = Amaranthus retroflexus (red root pigweed)
ZEMA = Zea mays (maize)
A = Fenoxaprop-p-ethyl
B2 = Nicosulfuron
B2 = Thifen~ulfuron
B3 I Primigulfuron
B4 ~ 3-(4,6-Dimethoxypyrimidin-2-yl)-1-[3-(N-methyl-N-
methyl~ulfonylamino)-2-pyridyl~ulfonyl]urea
B5 = DPX-9636
B6 , Imazethapyr
B7 = Atrazine
B8 = Bromoxynil
B9 = Dicamba
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