Institute of Ag Professionals
Proceedings of the
2004 Crop Pest Management Shortcourse
www.extension.umn.edu/AgProfessionals
Do not reproduce or redistribute without the written consent of author(s).
Herbicide Antagonism and
herbicide-fertilizer interactions
Crop Pest Management Short Course
Joe V Gednalske
Manager Product Development
Agriliance
Herbicide Antagonism
Definition: Chemical factors in the
spray tank which interfere with the
normal activity of the herbicide
Sources of Antagonism
•
•
•
•
•
Herbicide with other herbicides
Herbicide with other pesticides
Herbicide with the spray water
Herbicide with adjuvants
Herbicide with fertilizer
Herbicide antagonism to other
herbicides
Herbicide Antagonism
• The most common antagonism is when
post emergence grass herbicides are
mixed with post emergence broadleaf
herbicides
• Antagonism can be greater on certain
weeds or when weeds are stressed due to
environmental conditions like drought.
Herbicide to herbicide antagonism
• Examples of tank mixed herbicides
reducing the efficacy of one of the
products
– Poast and Basagran
– 2,4-D or Banvel and Achieve
– Steadfast Option and Accent with dicamba
• that is why reduced of dicamba are recommended
– Option and atrazine
– Many ,many others
Herbicide to herbicide antagonism
in glyphosate era
• As we develop tolerant weeds to glyphosate
many herbicides will be tank mixed.
• Potential antagonists
! atrazine
! cell membrane disruptors
! some salt formulated herbicides
• Many will need to be evaluated
• Often these antagonism’s can be overcome with
additional glyphosate, AMS or adjuvants
Summary Herbicide antagonism
with other herbicides
• Know which herbicides are potential
problems
• Avoid tank mixing under stress conditions
or for difficult to control weeds
• If products must be mixed look at higher
use rates to the labeled max, use the best
adjuvant ,and higher AMS rates
Herbicide antagonism with other
pesticides
Herbicide antagonism with other
pesticides
• Most often, interactions with other
pesticides are crop injury or
incompatibilities.
• True antagonism was rare
Herbicide and Fungicide
Antagonism
• As soybean rust comes into the US many new
products will be mixed with current herbicides.
– These products will need to be evaluated on a
product by product basis.
• Early work in South Africa and Brazil indicates
no major issues in tank mixes between
fungicides and glyphosate.
– Timing of applications may be an issue
– Application technique is different from herbicides
Herbicide Antagonism from Spray
Water
Herbicide Antagonism from Spray
Water
• Many herbicides are effected by the quality of
water which it is applied with.
• Minerals, clay, and organic matter can reduce
the effectiveness of herbicides
• Clay inactivates glyphosate and paraquate
• Minerals (cations) antagonize 2,4-D amine
,MCPA ,amine , dicamba , glyphosate , Liberty
,and Poast
• Organic matter inactivates many herbicides
Herbicide antagonism from spray
water (continued)
• Glyphosate is the most common herbicide
effected by water quality
• Water containing sodium ,calcium,
magnesium , potassium ,or iron can effect
glyphosate’s performance
• A spray water analysis can determine the
amount of these ions in your water
• Ammonium Sulfate is the most common product
added to overcome antagonism
Herbicide antagonism from spray
water (cont)
• NDSU developed the following formula
to determine the amount of AMS to
overcome antagonism
• lbs. AMS/100 gal = 0.005 x ppm Na +
0.002 x ppm K + 0.009 x ppm Ca +
0.014 x ppm Mg.
• ** This only accounts for AMS to
overcome antagonism additional AMS
is helpful as an adjuvant
Herbicide antagonism from spray
water (cont)
• Agriliance did nation wide survey of spray
water quality
• Over 800 samples nation wide
• 143 for Minnesota
A G R IL IA N C E
S p r a y W a te r A n a ly s is R e p o r t
A g r ilia n c e B . D . M .
C om pany N am e:
M a ilin g A d d r e s s
C it y
S ta te
Z ip
P hone
=
=
=
=
=
=
=
R IV E R F A L L S
W I
54022
6 5 1 -4 5 1 -4 9 4 2
W a te r S
S a m p le
D a te R e
D a te R e
=
=
=
=
W E LL
U W R F LA B FA R M 2
4 -1 8 -0 3
4 -1 8 -0 3
o u rc e
ID .
c e iv e d
p o rte d
A G V IS E L a b N o
pH
G R E G D A H L
A n ta g o n is m
C o e f f ic ie n t
12181
A .M .S .
R e q u ir e m e n t
7 .8
4 ppm
X
0 .0 0 5 *
=
0 .0 1 7 7 1 4
C a lc iu m
65 ppm
x
0 .0 0 9 *
=
0 .5 8 5 4 2 5
M a g n e s iu m
29 ppm
x
0 .0 1 4 *
=
0 .4 1 0 9 5
1 ppm
x
0 .0 0 2 * *
S o d iu m
P o ta s s iu m
H a rd n e s s
S A R
( m g e q u iv a le n t C a C O 3 /L )
( S o d iu m A d s o r p tio n R a tio )
=
0 .0 0 2 1 2 6
285 ppm
0 .0 9
R e c o m m e n d e d A M S r e q u ir e d f o r 1 0 0 g a llo n s o f w a t e r =
1 . 0 1 6 2 1 4 lb s A M S
N o te : T h e a m o u n t o f A M S g iv e n a b o v e is a n e s t im a t e o f t h e a m o u n t r e q u ir e d to
o v e r c o m e t h e a n t a g o n is t ic e f f e c t o f t h e c a t io n s in y o u r w a t e r . T h is e s t im a t e is b a s e d
o n t h e c a t io n s lis t e d a b o v e a n d th e c o e f f ic ie n t s p r o v id e d b y N o r t h D a k o t a S t a t e
U n iv e r s it y * a n d A g r ilia n c e * * .
Herbicide antagonism from spray
water (cont)
• Study at UWRF 2003 & 2004 comparing
glyphosate performance in two water
sources
• Hard water = 1722 ppm hardness 2003
and 2300 ppm hardness 2004
• Soft water = 12 ppm hardness 2003 and
285 ppm in 2004
Common Lambsquarters Control With AMS
Containing Adjuvants 2003
1722 ppm
% Control
45
12 ppm
% Control
56
4 lb /100 gal
60
64
8.5 lb/100 ga
70
70
17 lb /100 ga
65
61
1.25% v/v
79
81
2.5% v/v
80
86
Treatment
RATE
RU WeatherMax
reduced
RU WeatherMax +
AMS
RU WeatherMax +
AMS
RU WeatherMax +
AMS
RU WeatherMax +
Water conditioner 3
RU WeatherMax +
Water Conditioner 1
Combined results 4 trials RF,WI
&Rosemount ,MN
Foxtail Control With AMS Containing Adjuvants
2003
1722 ppm
%Control
35
12 ppm
% Control
74
4 lb/100 ga
65
79
8.5 lb/100g
74
85
17lb/100 g
77
86
1.25% v/v
77
86
2.5% v/v
89
85
Treatment
RATE
RU WeatherMax
reduced
RU WeatherMax +
AMS
RU WeatherMax +
AMS
RU WeatherMax +
AMS
RU WeatherMax +
Water conditioner # 3
RU WeatherMax +
Water conditioner # 1
Combined results 4 studies
RF,WI&Rosemount,MN
Grass Weed Control With Glyphosate and Nitrogen
Containing Adjuvants in Two Waters 2004
Treatment
Adj. Rate
TD High Tech
Reduced
Rate
8.5 lbs
TD High Tech +
AMS
TD High Tech +
17 lbs
AMS
TD High Tech +
2.5% v/v
Water Conditioner #1
TD High Tech +
0.5% v/v
Water Conditioner #2
TD High Tech +
1% v/v
Water Conditioner #3
LSD (P=0.05)
uwrf
Hard water
% Control
53
Soft Water
% Control
83
91
90
91
93
97
98
81
85
93
95
6
5
C. Lambsquarters Control With Glyphosate and
Nitrogen Containing Adjuvants in Two Waters 2004
Treatment
Adj. Rate
TD High Tech
Reduced
Rate
8.5 lbs
TD High Tech +
AMS
TD High Tech +
17 lbs
AMS
TD High Tech +
2.5% v/v
Water Conditioner #1
TD High Tech +
0.5% v/v
Water Conditioner #2
TD High Tech +
1% v/v
Water Conditioner #3
LSD (P=0.05)
uwrf
Hard water
% Control
20
Soft Water
% Control
43
40
45
43
48
98
97
81
75
91
93
5
6
Velvetleaf Control With Glyphosate and Nitrogen
Containing Adjuvants in Two Waters 2004
Treatment
Adj. Rate
TD High Tech
Reduced
Rate
8.5 lbs
TD High Tech +
AMS
TD High Tech +
17 lbs
AMS
TD High Tech +
2.5% v/v
Water Conditioner #1
TD High Tech +
0.5% v/v
Water Conditioner #2
TD High Tech +
1% v/v
Water Conditioner #3
LSD (P=0.05)
Hard water
% Control
36
Soft Water
% Control
50
65
68
76
74
93
95
68
73
83
89
7
7
Summary Herbicide antagonism
from spray water (cont)
• Hard water greatly effects herbicide
performance
• Do not take water test results as all the AMS you
need
– AMS also helps with antagonism that occurs on the
leaf surface
– some believe that the antagonism from the spray
water does not occur until the droplet dries on the leaf
– AMS also increases permeability ,uptake and
translocation (species specific)
• All water conditioners are not equal
Herbicide antagonism from
adjuvants
Herbicide antagonism from
adjuvants
• Generally antagonism is not an issue
– Crop tolerance and poor control more likely
• COC and glyphosate can be a problem
– Oil adjuvants are generally not recommended with
glyphosate.
• When tank mixing oil loving herbicides with
glyphosate antagonism may be an issue.
– Large variation between products depending on
emulsifier system and oil used.
Broadleaf Contr ol with Reduced Rate Glyphosate and Oils
10 0
90
80
% Con tr ol
70
60
50
Glyphosate
NIS + AMS
AMS + Crop Oil
AMS + High
S urfactant Oil
Concentrate
AMS + MSO
Broadleaf Control with Reduced Rate Glyphosate
1 00. 0
90. 0
80. 0
% Control
70. 0
60. 0
50. 0
Cl ethodi m+
AM S
Cl ethodim +
AMS + NIS
Clethodi m +
AMS + High
Surfactant Oil
Concentrate
Clethodim +
AMS + MS O
Cl ethodim +
AMS + COC
Summary ,Herbicide antagonism
from adjuvants
• Oils may be a problem with glyphosate
– Large variation between products
– Variation may be weed specific
Herbicide antagonism with
fertilizers
Herbicide antagonism with
fertilizers
• With the additional applications of the
glyphosate era , growers have begun
applying fertilizers with the glyphosate
• By carefully checking the products and
practices successful weed control can be
accomplished
Factors to consider when putting
fertilizers with herbicide
• Mixing compatibilities
•
•
•
•
•
•
If you have not done it before, jar test
Difference in spray water may affect this
Large variance from batch to batch
Ex: 10-34-0
There are compatibility agents that may help.
More compatibility problems in low temperature water
• Antagonism
– Influence by cations present and amount
– The same herbicides affected by poor quality water
probably would be affected by fertilizers.
Glyphosate Antagonism
• Researchers have thought that cations
found in fertilizers, attaching to the
glyphosate ion may prevent it from
entering the plant.
• Dr. Don Penner and Dr. John Nalajewa
have both presented evidence on this.
• The formulation of the micronutrient also
has an influence on the amount of
antagonism.
Proposed structure of the 2:1 glyphosate:Mn2+ complex. In the equatorial
positions Mn2+ is bound by the amine N (as shown in ESR spectra) and the
carboxyl O of two glyphosate molecules.
Mark L. Bernards, Kurt D. Thelen, Donald Penner, Rahendra B. Muthukumaran, and John L. McCracken Department
of Crop and Soil Sciences, Department of Chemistry, Michigan State University, East Lansing, MI 48824
GLY
GLY
GLY
FE
Mark L. Bernards, Kurt D. Thelen, Donald Penner, Rahendra B. Muthukumaran, and John L.
McCracken
Department of Crop and Soil Sciences, Department of Chemistry, Michigan State
University, East Lansing, MI 48824
Mark L. Bernards, Kurt D. Thelen, Donald Penner, Rahendra B. Muthukumaran, and John L. McCracken Department
of Crop and Soil Sciences, Department of Chemistry, Michigan State University, East Lansing, MI 48824
% G ra s s C o nt ro l a t D i f f e re nt R a t e s o f G l y p ho s a t e
100
80
60
%Co nt ro l
3 4 DAT
40
20
0
2 2 o z RU Cla s s Ac t
2 2 o z R U C l a s s A c t Ir o n
S ulf a t e
Glyphosate a nd Iron Sulfate sprayed One Hour Apart
100
80
60
% Con tro l
41 DAT
40
20
0
Gras s
Ve lvet Leaf
RU + Iron Sulfate (Tank Mi xed)
RU Foll owed By Iron S ulfate
I ron Sul fate Foll owed By RU
% G i a nt R a g w e e d C o nt ro l a t D i f f e re nt R a t e s o f
G l y p ho s a t e
100
80
60
%Co nt ro l
12 D A T
40
20
0
2 2 o z RU
2 2 o z RU
3 3 o z RU
4 4 o z RU
2 2 o z RU
Cla s s Ac t
Cla s s Ac t
Cla s s Ac t
Cla s s Ac t
Cla s s Ac t
Ir o n
Ir o n
Ir o n
Fo l l o w e d
S ulf a t e
S ulf a t e
S ulf a t e
B y Ir o n
S ulf a t e
Cla s s Ac t
Spray Water Sample – Distilled + 1 qt/ac Iron
Sulfate
Greg Dahl
Antagonism
AGVISE Lab No
12143
pH
Coefficient
A.M.S.
Requirement
3.5
Sodium
1934
ppm
X 0.005* =
9.6692
Calcium
2
ppm
x 0.009* =
0.02042
0.01
ppm
x 0.014* =
0.00014
10
ppm
x 0.002** =
0.02041
1280
ppm
X .014 =
6
ppm
Magnesium
Potassium
Iron
Hardness (mg equivalent CaCO3/L)
SAR (Sodium Adsorption Ratio)
17.92
352.08
Recommended AMS required for 100 gallons of water =
27.63
lbs AMS
Summary, Herbicide antagonism
with fertilizers
• Fertilizers in the spray tank can greatly
effect herbicide performance
• Split applications with the glyphosate first,
is the best
• Micro formulation is very important in
minimizing problems
Thank You
• Questions ???