The main weeds that harm the Maize are:
Crabgrass, Barnyard grass, Green bristlegrass, Goosegrass, Redroot pigweed, purselane, Acalypha australis, Cirsium japonicum, Cirsium segetum, Leptochloa chinensis, Field bindweed, Common dayflower, Alternanthera philoxeroides, Cyperus rotundus, Cyperus difformis, Horseweed herb, etc..
Classification of main Herbicides for Maize
1: Claffification by the application time
Pre-emergence herbicides: like acetochlor, metolachlor, s-metolachlor, Atrazine
Post-emergence herbicides(3-5 leaf stage): like Nicosulfuron, Atrazine, Mesotione
Post-emergence herbicides(middle-late stage of Maize): like Paraquat, Glyphosate
2: Classification by treatment method
Soil treatment, Pre-emergence herbicides,
Stem and leaf treatment, Post-emergence
Soil treatment+stem&leaf treatment: Universal type(pre and post emergence)
Main Maize herbicides - Atrazine
Main formulations are 38%, 56%, 50% SC, 48%, 80% WP
Advantage:
Safe for Maize
Can kill annual weeds(has better control effect for annual broadleaf weeds than annual grass weeds)
Better water solbility, better leaching ability
Can be used for both pre&post emergence
Disadvantage:
May cause phytotoxicity for succedding crops like vegetables, soybeans, rice, wheat, etc.
May cause pollution for under-ground water
Bad control effect for annual grass weeds like crabgrass.
Main Maize herbicides - amide herbicides
Main products: Acetochlor,Butachlor, Metolachlor
Used as pre-emergence herbicides, more used as Acetochlor+Atrazine
Advantage:
Pre-emergence herbicides used as soil treatment, can control annual grass weeds and broad-leaf weeds;
Can be adsorbed by weeds' root, bud, stem and leaf;
Long persistant period as 2-3 months
Disadvantage:
Has better comtrol effect for annual grass weeds than annual broad-leaf weeds; No effect for perennial weeds
Main Maize herbicides - sulfonylurea herbicides - Nicosulfuron
Mainly control annual grass weeds and some broad-leaf weeds, the only one product that has high control effect of annual grass weeds in sulfonylurea herbicides
Advantage:
wide spectrum of weed control, good effect and stability, kill weeds' root, low requirement for soil and weather. Safe for most known corn like dent corn, flint corn.
Disadvantage:
Sensative for sweet corn and waxy corn. The order of security to maize: Dent maize>flint maize>pop maize>sweet maize.
Sensative for the maize with 3 leaves before and 5 leaves after.
Main Maize herbicides - triketone herbicides - Mesotrione
Used to control broad-leaf weeds and some grass weeds.
Advantage:
Fast speed to kill weeds, no sensative to maize, good control effect for most broad-leaf weeds.
Can apply in full growth period of the Maize.
Disadvantage:
Pop maize is sensative to Mesotrione.
Bad control effect for some grass weeds like Green bristlegrass, Purslane, Calystegia hederacea, etc..
Bad control effect for the weeds with 4-6 leaves, the weeds will turn geen after application.
Bad control effect for Cyperus rotundus.
Can not kill the weeds' root thoroughly.
Main mixture herbicides for Maize in the market
1: Acetochlor+Atrazine
Main stream pre-emergence maize herbicides is Acetochlor+Atrazine, Propisochlor+Atrazine, Butachlor+Atrazine. The control effect decrease from the 1st to the 3rd, the safety is opposite. In application, choose mixture with higher content of Atrazine and lower content of amide herbicides, can have better control effect, high safety and longer persistance period.
Advantage:
Pre-emergence herbicides used as soil treatment, can control annual grass weeds and broad-leaf weeds;
Can be adsorbed by weeds' root, bud, stem and leaf;
Long persistant period as 2-3 months
Disadvantage:
Has better comtrol effect for annual grass weeds than annual broad-leaf weeds; No effect for perennial weeds
2: Nicosulfuron+Atrazine
The best safe ratio for Nicosulfand Atrazine mixture is 1:12(application qty per unit area. This recipe decrease Nicosulfuron's content, lift the safety factor, increase the control effect for broad-leaf weeds and the cost is acceptable.
3: Nicosulfuron+Mesotrione+Atrazine
The main ratios for the mixture are like 1-4% Nicosulfuron+3-7% Mesotrione+16-20% Atrazine, can control both both grass weeds and broad-leaf weeds. 3 mixtures can increase the control spectrum and decrease the application qty per unit area, lift the safety for the Maize. This mixture's characteristics are:
1: Pre and Post-emergence, stem and leaf treatment, also soil treatment, can effectively control kinds of annual grass weeds and broad-leaf weeds, good effect for nutsedge and kinds of perennial weeds.
2: Quick acting, can kill the weeds thoroughly, resistance to low temparature and dry weather, can replace all post-emergence Maize herbicides, is the best one-off herbicides. Save time, money and labor.
3: Have 3 active ingredients and not easy for the weeds to rise resistance.
Control targets: Can control nutsed, annual and perennial grass weeds, annual broad-leaf weeds. Has good effect for some malignant weeds like Green bristlegrass, Common dayflower, Eriochloa villosa, etc.
4: Mesotione+Atrazine
Advantage:
Post-emergence, stem and leaf treatment, quick acting and safe for most Maize.
Cotrol both grassy and broad-leaf weeds.
Can be used in 3-8 leaves stage of Maize.
Disadvantage:
Poor control effect for some grass weeds like green bristlegrass, etc..
If there's rainny weather after application, the weeds are easier to turn green
5: Mesotione+ S-metolachlor/Metolacor/Acetochlor/Butachlor+Atrazine
Order of safety: Mesotione+Acetochlor+Atrazine
Syngenta's recipe is 3% Mesotione+24.7% S-metolachlor+10.8% Atrazine
That's a mixture really works well with pre&post-emergence stem and leaf treatment. Main used as post-emergence control of elder broad-leaf weeds, especially for malignant broad-leaf weeds, also can control some grassy weeds.
High safety for sweet maize, hybrid maize, glutinous maize, pop maize.
Has good effect for abutilon, crabgrass, barnyardgrass, sedge family, cruciferous, legume, bacon weed,
6: Topramezone+ S-metolachlor/Metolacor/Acetochlor/Butachlor+Atrazine
This mixture's control effect for grassy weeds is little better than the mixture with Mesotione.
Very Good control effect for Redroot pigweed, Goosegrass, Green bristlegrass, Abutilon, Pigweed;
Good effect for crabgrass, Purslane, etc.;
Long lasting;
Basicly no effect for nutsedge; Elder grass may turn green after application
7: Isoxaflutole+ S-metolachlor/Metolacor/Acetochlor/Butachlor+Atrazine
This mixture can control both grassy weeds and broad-leaf weeds, like abutilon, crabgrass, green bristlegrass, purslane, redroot pigweed, etc..
Isoxaflutole has a special function “re-activating”, it can be activated again by the fainfall after the application, and kill the weeds again.
Long lasting for 4 months max.