• Mechanical and chemical mixing of two or more herbicides having different mode of action and varying level of activity and selectivity forms herbicide mixtures.
• Herbicides of the same class or different classes having similar mode of action are not ideal for herbicidal mixture.
• Herbicides having similar spectrum of weed control should not be opted for mixing.
Types of herbicide mixtures
1) Factory mix/premix/readymix
It is the mixture of desired herbicides prepared in the factory itself with definite proportions.
e.g., Isoguard plus (Isoproturon + 2,4-D)
Aniloguard plus (Anilophos + 2,4-D)
Primaguard (Atrazine + Metolachlor)
Atlantis (Mesosulfuron-methyl + Iodosulfuron methyl sodium)
Almix (Metsulfuron methyl + chlorimuron ethyl) – used in rice
Pursuit plus (Pendimethalin + Imazethapyr)
2) Tank mix/ field mix herbicide mixtures
It is mechanical mixing of two or more herbicides before their application in the field.
e.g., Atrazine + Alachlor
Atrazine + Pendimethalin
Isoproturon + Tralkoxydim
Sethoxydim + Chlorsulfuron
EFFECTS OF HERBICIDE MIXTURE INTERACTIONS
1) Synergistic effect: It is derived from the cooperative action of two or more herbicides in a mixture. (AB) > (A) + (B) Mixture effect of herbicide is more than the effect of herbicide A and B independently.
2) Antagonistic effect: The decrease in normal biological activity of one or all component herbicides in a mixture is referred as antagonistic effect. If (A) > (B) then (AB) < (A)
3) Additive effect: It refers to the combined action of component herbicides in the mixture when the total effect of mixture = sum total effect of the component herbicides when applied independently. (AB) = (A) + (B)
4) Enhancement effect: It generally occurs when adjuvant is mixed with active ingredient in the formulation and it increases the efficacy of herbicide than obtained with active ingredient alone. e.g., Fenoxaprop-p-ethyl
• Fenoxaprop-p-ethyl is a grass killer used in soybean under the tradename “whip super”, while same herbicide is used in wheat under different tradename “pumasuper”.
• The differential action of same herbicide is attributed to different adjuvants used in the formulations.
Advantages of herbicide mixtures
• Controls broad spectrum weeds.
• Prevents shift in weed flora.
• Delays development of resistance in weeds.
• Increases the weed control efficiency.
• Reduced dosage of herbicides per unit area.
• Because of reduced rate of application reduced residue in crop and environment.
HERBICIDE MIXTURES FOR CROPS
Anilophos (0.4 kg) + 2,4-DEE (0.5 kg)/ha
Butachlor (1 kg) + Propanil (2.0 kg)
Anilophos (0.3 kg) + chlorimuron (0.004 kg)
Anilophos (0.3 kg) + metsulfuron – methyl (0.004 kg)
Pretilachlor + 2,4-DEE for upland rice
2) Wheat and Barley
Diclofop-methyl (750 g) + Isoproturon (500g)
Isoproturon (750 g) + 2,4-D (250 g)
Clodinafop (60 g) + Isoproturon (500 g)
Fenoxaprop – p- ethyl (120 g) + 2,4-D (500g)
3) Maize and sorghum
Atrazine (0.5 kg) + Alachlor (1.0 kg)
Atrazine (0.75 kg) + Pendimethalin (0.75 kg)
Atrazine + 2,43-D
Pendimethalin + Imazethapyr
Metribuzin + Chlorimuron ethyl
Oxadiazon + Metolachlor
Fluchloralin + Metolachlor
Pendimethalin + Diuron
Atrazine + 2,4-D
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