Preplant Incorporated and Preemergence Surface

acetochlor (Surpass or Cadence)

Rate 0.8 to 3 lb ai/a. Consult appropriate label for rates.

Time Apply preplant or preemergence.

Remarks Use lower rates on coarse soils with low organic matter. May be surface-applied or incorporated into top 1 to 2 inches of soil. If rain or 0.25 to 0.75 inch of overhead irrigation does not occur within 7 days of a surface application, shallowly incorporate herbicide with a rotary hoe or similar device. May tank mix with several other herbicides to broaden activity.

Caution Improper incorporation methods or poor soil preparation may reduce weed control. Consult label for crop rotation restrictions.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide

atrazine (several trade names)

Rate Consult label for yearly changes.

Time Apply preplant or preemergence by selecting rates depending on soil type listed on label.

Remarks Activate with overhead irrigation in 7 days or incorporate mechanically in top 2 inches of soil for rill-irrigated fields east of the Cascades. Control of barnyardgrass and yellow foxtail is poor if the soil surface remains dry or if these grasses grow beyond the two-leaf stage. Do not plant crops other than corn during the season of treatment. Other crops can be planted the next year west of the Cascades, if treated before June 10 with 2 lb/a or less; east of the Cascades, use other herbicides when planting corn the next year.

Caution A restricted-use herbicide. Also, any product or premix containing more than 4% atrazine is restricted use (Atrazine 4L is 42% atrazine). Some populations of redroot pigweed, groundsel, kochia, and lambsquarters have evolved resistance to atrazine. Combine other herbicides with atrazine if these species are present. Do not exceed 2 lb ai/a for any single application. Do not exceed 2.5 lb ai/a per year. Do not graze treated area or feed treated forage to livestock for 45 days after application. After harvest, plow and thoroughly mix the soil to reduce possible injury. Do not apply through any type of irrigation system.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazine

dimethenamid-P (Outlook)

Rate 0.56 to 0.98 lb ai/a (12 to 21 fl oz/a Outlook)

Time Apply preplant incorporated, preplant surface, or preemergence surface.

Remarks Consult label for application rate in relation to soil type. Use lower rates on coarse soils with low organic matter or low cation exchange capacity. Control is best if incorporated into soil by overhead moisture or a light mechanical tillage (1 to 2 inches deep) before weed seedlings emerge. May be tank mixed with other herbicides to improve weed control. Control of wild proso millet can be enhanced if Outlook is applied postplant surface after preplant-incorporating Dual Magnum.

Caution Apply through irrigation systems as described on the label. Delayed and erratic emergence or leaf wrapping of sweet corn may occur if conditions are extreme (heavy rain and extended periods of water-saturated soil and/or cool weather) during germination and emergence, particularly for preplant-incorporated applications followed by cool, wet weather. Do not apply on sweet corn grown for seed.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide

mesotrione (Callisto)

Rate 0.078 to 0.094 lb ai/a (2.5 to 3 fl oz/a Callisto)

Time Apply preemergence surface after planting.

Remarks Good control of some broadleaf weeds. Tank mix with atrazine to improve weed control.

Caution Some sweet corn varieties are more sensitive than others. Rotational interval is 18 months for peas, snap beans, cucurbits, beets, and many other crops. Crop yield may be reduced if applied to corn treated with the insecticides Counter or Lorsban. Do not apply more than 0.24 lb ai/a per year (7.7 fl oz).

Site of action Group 27: inhibits 4-hydroxyphenylpyruvate dioxygenase (4-HPPD)

Chemical family Triketone

S-metolachlor + atrazine + bicyclopyrone + mesotrione (Acuron)

Rate 2.15 to 2.58 lb ai/a (2.5 to 3 quarts/a Acuron)

Time Preemergence only in sweet corn

Remarks Acuron is a premix of atrazine, bicyclopyrone, mesotrione and S-metolachlor plus the safener benoxacor. Bicyclopyrone is an HPPD inhibitor herbicide with soil residual that will control pigweed and nightshade. Acuron Flexi does not contain atrazine. Rate is dependent on soil organic matter.

Caution A restricted use herbicide. Application to emerged corn seedlings will typically cause unacceptable injury. Grazing Restriction: To avoid possible illegal residues, do not graze or feed forage from treated areas for 45 days following application. If crop is lost that has been treated with Acuron (field, seed, silage), sweetcorn, yellow popcorn, can be replanted immediately. Small grain cereals including wheat, barley and rye can be planted 4 months after application. Dry bean and potato can be planted 10 months and all other crops after 18 months.

Site of action (S-metolachlor) Group 15: inhibits very long chain fatty acid synthesis; (atrazine) Group 5: photosystem II inhibitor; (bicyclopyrone and mesotrione): Group 27: inhibits 4-hydroxyphenylpyruvate dioxygenase (4-HPPD).

Chemical family (S-metolachlor) Chloroacetamide; (atrazine) Triazine; (bicyclopyrone and mesotrione) Triketone

pendimethalin (Prowl H2O, Stealth)

Rate 0.95 to 1.90 lb ai/a (2 to 4 pints/a Prowl H2O) depending on soil texture and organic matter content.

Time Apply preemergence only; do not preplant-incorporate. Apply over a uniform seedbed with corn seed planted 1.5 inches deep to ensure selectivity.

Remarks Note rates listed on label for different soil types and organic-matter contents.

Caution May cause lodging of sweet corn. Planting deeply and hilling during cultivation may help to reduce lodging. Do not incorporate. Use only shallow cultivation to reduce soil mixing at or near seed. Do not apply to reduced-till or no-till sweet corn.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

pyroxasulfone (Zidua or Zidua SC)

Rate 0.081 to 0.211 lb ai/a (2.5 to 6.5 oz/a Zidua SC) depending on soil texture

Time Apply preplant incorporated up to 14 days before planting or preemergence surface. May be applied in a single application or in sequential applications.

Remarks Residual control of annual ryegrass and rattail fescue and many broadleaved weeds. Preplant-surface applications are not recommended in sweet corn. Sequential preemergence or postemergence application can be made, but do not exceed the maximum cumulative rate allowed by soil type per season. Zidua may be broadcast surface applied in the fall or winter to control winter annual weeds germinating in fall.

Caution Corn seed must be planted a minimum of 1 inch deep. If a labeled crop treated with Zidua is lost to crop failure because of environmental factors, corn may be replanted, but do not repeat application of Zidua after crop failure. Crop rotation intervals are 18 months for grasses grown for seed, and 11 months for small grains, snap beans, and peas. May injure corn on gravelly loams at 3 oz/a.

Site of action Group 15: Very long chain fatty acid synthesis inhibitor

Chemical family Chloroacetamide

pyroxasulfone + fluthiacet methyl (Anthem)

Rate 0.084 to 0.218 lb ai/a (5 to 13 oz/a Anthem)

Time Preemergence. See label for application timing, soil type, organic matter, and rate information.

Remarks Preplant applications are not recommended for sweet corn. Apply alone or in a tank-mixture to broaden weed spectrum. Where emerged weeds are present at the time of application, use appropriate weed control measures to control emerged weeds. For early preplant applications in reduced-tillage systems, use the higher rate for soil type. Requires rainfall or irrigation to activate.

Caution Do not exceed a total of 16.3 oz/a of Anthem per season. See label for rotational restrictions. Preplant surface applications are not recommended on coarse soils where annual rainfall exceeds 40 inches. Do not harvest field corn for forage for 30 days after application. Do not harvest for grain for 70 days after application. Do not harvest sweet corn forage or ears until 40 days after application. Make only one preplant/preemergence application per season.

Site of action (pyroxasulfone) Group 15: inhibits long chain fatty acid synthesis; (fluthiacet methyl) Group 14 protoporphyrinogen oxidase inhibitor

Chemical family (pyroxasulfone) Chloroacetamide; (fluthiacet methyl) Imine

pyroxasulfone + fluthiacet methyl + atrazine (Anthem ATZ)

Rate 1.126 to 2.253 lb ai/a (32 to 64 oz/a Anthem ATZ)

Time Preemergence. See label for application timing, soil type, organic matter, and rate information.

Remarks Preplant applications are not recommended for sweet corn. Apply alone or in a tank-mixture to broaden weed spectrum. Where emerged weeds are present at the time of application, use appropriate weed control measures to control emerged weeds. For early preplant applications in reduced-tillage systems, use the higher rate for soil type. Requires rainfall or irrigation to activate.

Caution Restricted-use herbicide with atrazine. Do not exceed a total of 39 oz/a of Anthem ATZ per season on coarse-textured soils or 70 oz/a on fine-textured soils. See label for rotational restrictions. Preplant surface applications are not recommended on coarse soils where annual rainfall exceeds 40 inches. Do not harvest field corn for forage for 60 days after application. Do not harvest for grain for 70 days after application. Do not harvest sweet corn forage or ears until 45 days after application. Make only one preplant/preemergence application per season.

Site of action (pyroxasulfone) Group 15: inhibits long chain fatty acid synthesis; (fluthiacet methyl) Group 14: protoporphyrinogen oxidase inhibitor; (atrazine) Group 5: photosystem II inhibitor

Chemical family (pyroxasulfone) Chloroacetamide; (fluthiacet methyl) Imine; (atrazine) Triazine

saflufenacil (Sharpen)

Processing varieties only, not including sweet corn grown for seed or fresh market varieties.

Rate 0.044 lb ai/a (2 fl oz/a)

Time Apply early preplant surface (15 to 30 days before planting), preplant surface or incorporated (0 to 14 days before planting), and post-plant surface (before corn emergence).

Remarks Burndown broadleaf weed control with residual control dependent on rate. Does not control grasses. An adjuvant system is required such as methylated seed oil plus ammonium sulfate for optimum broadleaf burndown activity. If only residual broadleaf weed control is desired, Sharpen can be applied at 1.0 fl oz/a (all soil types) with an adjuvant system any time before corn emergence for. PHI is 80 days. Tank mix with Outlook or other soil active herbicides to improve residual control.

Caution Do not apply after corn has emerged because corn will be severely injured.

Site of action Group 14 Protoporphyrinogen IX oxidase (PPO) inhibitor

Chemical family Pyrimidinedione

saflufenacil + dimethenamid-P (Verdict)

Processing sweet corn only

Rate 0.044 lb ai/a saflufenacil + 0.39 lb ai/a dimethenamid-P (10 fl oz/a)

Time Apply preplant surface or preplant incorporated (0 to 14 days before planting), and post-plant surface (before corn emergence).

Remarks Burndown broadleaf weed control with residual broadleaf and grass control. An adjuvant system is required for optimum broadleaf burndown activity such as methylated seed oil plus ammonium sulfate. PHI is 80 days. Plant corn >1/2 inch deep to avoid injury, and make sure the corn row has closed before applying Verdict.

Caution Do not apply after corn has emerged because corn will be severely injured. Do not apply where an at-planting application of an organophosphate or carbamate insecticide was applied because severe injury may result. Do not apply to soils with less than 3% OM. Some hybrids may be less tolerant to Verdict than others.

Site of action (saflufenacil) Group 14: Protoporphyrinogen IX oxidase (PPO) inhibitor; (dimethenamid-P) Group 15: inhibits very long chain fatty acid synthesis

Chemical family (saflufenacil) Pyrimidinedione; (dimethenamid-P) Chloroacetamide

simazine (Princep 4L, Simazine 4L, and others)

Rate 1.6 to 4 lb ai/a (1.6 to 4 quarts/a, depending on product)

Time Preemergence, apply before weeds and corn emerge.

Remarks Maximum rate on highly erodible soils is 1.6 quarts/a if less than 30% of the soil is covered with plant residues. Preharvest and pregrazing interval is 45 days. Can be preplant-incorporated.

Caution A restricted-use herbicide in Washington. Do not plant crops other than corn for 1 year. Do not graze treated areas. Do not exceed 2.5 quarts/a per year. After harvest, plow and thoroughly mix the soil to reduce possible injury.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazine

S-metolachlor (Dual Magnum or Dual II Magnum with corn safener) or metolachlor (Parallel)

Rate Consult labels to adjust rates for soil types and organic matter content.

Time Apply preplant incorporated, preemergence, or early postemergence, before weeds germinate or yellow nutsedge emerges.

Remarks Activate with shallow incorporation or overhead moisture. Dual II has corn safener.

Caution Consult label for specific rates, depending on soil texture and especially organic matter, or for restrictions on planting sensitive crops within 4 to 5 months. Inhibits root and shoot growth.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide