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0.5-0.66 pt per acre has been more effective and provides stand reduction. It also controls ragweed, sunflower, and cocklebur. Crop 34 www.iGrow.org tolerance is excellent. Apply in a minimum of 10 gpa carrier for ground equipment. Alfalfa, canola, safflower, and grain sorghum may be planted in 12 months. Dry beans, soybeans, and sunflower may also be planted in 12 months, except in light soil with less than 12 inches precipitation in the preceding 12-month period. Avoid drift to sensitive crops. Do not allow livestock to graze treated fields or harvest grain or silage within 40 days after treatment. Do not apply by aircraft.
POST. Apply from crop emergence to 24 inches. Use drop nozzles to direct spray in larger corn. Thistles should be at least 4 inches but not at bud stage.
POST. Premix containing 0.38 lb clopyralid (Stinger) plus 2 lb 2,4-D amine per gal. The 2 pt rate provides the equivalent of 4 oz Stinger and 1 pt 2,4-D 4L per acre. Apply until the 5-leaf collar is visible or up to 8 inches. Do not apply late. Effective for Canada thistle and general broadleaves.
STARANE or COMET (fluroxypyr) Site of Action: 4
0.66 pt Starane or Comet 1.5L (0.12 lb ae)
0.4 pt Starane Ultra 2.8L (0.14 lb ae) Starane is a translocated postemergence herbicide used to control certain broadleaf weeds. Fluroxypyr provides an alternative mode of action to control ALS resistant kochia biotypes. Labeling also includes cocklebur, sunflower, common ragweed, and Venice mallow. Mustard, Russian thistle, pennycress, wild buckwheat, and other broadleaves require combination treatments. Starane has been tested extensively in SDSU tests; kochia control and corn tolerance have been excellent.
POST. Apply from emergence through 5-leaf collar stage.
BURNDOWN. For no-till, may be tank-mixed with other herbicides for use prior to planting. Minimum carrier is 8 gpa for ground equipment. May also be applied by air. Adjuvants are not usually used but may be added under dry conditions.
Weeds should be actively growing. Temperature below 45o and above 85o may result in reduced activity. Do not graze or harvest forage for 47 days or harvest grain or stover for 90 days after application.
POST. Apply 1.33 pt WideMatch containing 0.75 lb clopyralid (Stinger) plus 0.75 lb fluroxypyr (Starane) per gal. The 1.33 pt rate provides the equivalent of 0.33 pt Stinger plus 0.66 pt Starane. Apply from crop emergence through 5-collar stage. Refer to Stinger and Starane sections.
0.125-0.9 oz wt Harmony 50SG (0.004-0.028 lb ai) 0.083-0.6 oz wt Thief 75DF, Treaty 75DF, Unity 75DF, Volta 75DF (0.004-0.028 lb ai) BURNDOWN. Apply Harmony 50SG at 0.45-0.9 oz wt/A or 75DF product at 0.3-0.6 oz wt/A prior to planting or after planting but prior to corn emergence. May be tank-mixed with glyphosate to improve control of difficult weeds such as wild buckwheat, mustards, or lambsquarters. Add NIS at 0.25% v/v and AMS at 2-4 lb/A.
POST. Apply Harmony 50SG at 0.125 (1/8) oz wt/A or 75DF product at 0.083 (1/12) oz wt/A in field corn with 2-6 leaves or 1-5 leaf collars or up to 16 inches tall. Do not make more than one application per season. Add NIS (0.25% v/v) or COC (1% v/v) plus either AMS (2-4 lb/A) or UAN (28% N, 2-4 qt/A). Only apply to corn with a relative maturity of 88 days or more. May provide control or suppression of velvetleaf, lambsquarters, pigweed, smartweed, and mustards.
BURNDOWN. Vida is a preplant burndown herbicide. It is a non-selective, non-residual treatment for emerged weeds prior to planting corn. It has activity on broadleaf weeds including cocklebur, sunflower, lambsquarters, pigweed, Russian thistle, wild buckwheat, and wild mustard. Vida is used primarily in a tank-mix with glyphosate. Results used alone have been variable;
especially for kochia.
Rates of 0.5-1 oz per acre have been used in most tank-mixes.
Use the high rate for large (4-6 inches) weeds. Minimum carrier is 10 gpa for ground or 5 gpa for air. Labeled crops (corn, wheat, soybeans) may be planted immediately; allow 30 days for other food crops. Do not allow livestock to graze treated areas.
POST DIRECTED. Use Gramoxone Inteon as a directed spray. Provides a salvage option when weeds cannot be controlled with cultivation. Apply when corn is at least 10 inches. Arrange nozzles to spray no higher than the lower three inches of the corn stalk.
Coverage is especially important for dense or tall weeds.
2-4 pt Gramoxone Inteon 2L (0.5-1 lb ai) ($9.05-18.05) 1.3-2.7 pt Firestorm 3L (0.5-1 lb ai) BURNDOWN. Paraquat is a non-selective, non-residual, contact herbicide used at planting to control emerged grasses and broadleaves and topgrowth of perennials. Rates of 1.5 pt Gramoxone Inteon are adequate for most small weeds; high rate is for larger weeds (over 6 inches) or dense stands. Apply in a minimum of 10 gpa for ground or 5 gpa for air. NIS is important. Most mixtures with atrazine require surfactant at 1 pt/100 gal. Use 2 pt/100 gal with most combinations if nitrogen fertilizer carrier is used.
Liquid fertilizer containing phosphorus will reduce paraquat activity. Paraquat is highly toxic when ingested; follow handling and safety precautions.
Gramoxone may be tank-mixed in burndown treatments with postemergence and preemergence residual herbicides labeled for preemergence and burndown programs in corn.
GLYPHOSATE PRODUCTS (CONVENTIONAL CORN) Site of Action: 9 Glyphosate is available in several products having different formulations and different amounts (lb) of acid equivalent (ae) and active ingredients (ai). Some products require the addition of NIS; AMS products at the equivalent rate of 8.5-17 lb/100 gal are required for most formulations. Check crop use and application directions on the product being used.
BURNDOWN. Weeds should be growing actively. Water having more than 500 ppm combined calcium, magnesium, or iron may reduce activity; especially at high carrier volumes. Daytime temperatures below 55o F may also reduce activity. Avoid tillage for one day after treating annuals; 3-7 days for perennials. Carrier is 3-40 gpa for ground and 3-15 gpa for air. Maximum rate for air is 1 qt of 3 lb product. Use caution to avoid droplet drift to non-target crops. Follow cleanup procedures to avoid crop damage from equipment contamination.
SPOT TREATMENT. Use 2-4 qt of 3 lb ae per acre to control small patches of perennial weeds such as quackgrass or Canada thistle. It is usually applied with hand-held equipment. Crop contacted by spray or drift will be damaged or killed.
36 www.iGrow.org PREHARVEST. Several glyphosate products are labeled for preharvest use. Applications must be made 7 days prior to harvest and when grain moisture is 35% or less or corn has reached physiological maturity and maximum kernel fill is complete. Ground or aerial applications. Do not apply preharvest to corn grown for seed.
Glyphosate is a non-selective translocated herbicide with no soil residual weed activity. It controls both grasses and broadleaf species. Some products contain adequate surfactant, others require NIS. AMS at 8.5-17 lb/100 gal is required, especially if poor water quality, cool weather, or moisture stress may reduce control. Refer to section for Herbicide Resistant Corn for in-crop use.
Glyphosate rates in this section are listed for products having 3 lb acid equivalent (4 lb ai). Use the chart below to adjust for other concentrations.
The amount required varies according to weed species and size. Green foxtail, mustard, sandbur seedlings, and volunteer wheat seedlings are more susceptible than many other species. Suggested rate for glyphosate 3 lb ae product is 16 oz for most small annuals; 12 oz per acre may be adequate for some situations. Use 20-24 oz per acre for larger or more tolerant annuals. Rates of 32-48 oz is for perennials.
Glyphosate products are frequently used in tank-mix or premix combinations as preemerence soil-applied burndown treatments in no-till systems. Refer to specific glyphosate or tank-mix partner product label for approved herbicide combinations. For improved burndown, glyphosate may be tank-mixed with 2,4-D or dicamba and applied at least 7 days prior to planting.
HERBICIDE RESISTANT CORNHerbicides for use only on herbicide resistant corn hybrids are listed in this section. Herbicides listed for standard corn may also be used in weed control programs for herbicide resistant corn.
Premix containing 52.5% imazethapyr (Pursuit) + 17.5% imazapyr (Arsenal) active for postemergence control of many annual grass and broadleaved weeds. For use only on Clearfield corn hybrids. Lightning provides very good to excellent control of emerged weeds and has extended soil residual.
Results are best on small weeds, usually 2-3 inches. Lightning controls foxtail, lambsquarters, sunflower, velvetleaf, cocklebur, non ALS kochia, wild buckwheat, nightshade, and other annuals. Early postemergence applications give fair to very good control of wild proso millet, woolly cupgrass, and sandbur (1 in); an additional herbicide such as a reduced rate of Harness, Surpass, or other preemergence herbicides or Prowl or Pendimax at early postemergence will improve results in moderate or heavy infestations.
Dicamba, atrazine, or other broadleaf herbicide is required for more consistent pigweed, common waterhemp, or common ragweed control.
POST. Apply from spike to before corn is 18 inches. Minimum carrier is 10 gpa for ground or 5 gpa for air. Apply at 1.28 oz per acre;
one soluble bag treats 2 acres. Add NIS at 1 qt/100 gal and 28% N at 1-2 qt or AMS at 2.5 lb per acre. Refer to additive limitations that apply to tank-mix partners. Do not use liquid fertilizer as the carrier. Delay application for 48 hours if temperature remains below 40o F for 10 hours or more.
Rotation restrictions are 4 months for rye and wheat; 8.5 months for standard corn; 9.5 months for barley, soybeans, alfalfa, peas, and edible beans; 18 months for oats, sorghum, safflower, sweetcorn; 26 months for potatoes; and 40 months for crops not listed on the label.
For heavy grass pressure; Lightning may be used following soil applied herbicides such as Harness, Surpass, Prowl or Pendimax, Dual, or Outllook. Lightning may be tank-mixed with other herbicides, including 2,4-D, atrazine, Banvel, Basagran, Bicep, Buctril, Buctril/Atrazine, Callisto, Clarity, Distinct, Dual, Outlook, Guardsman, Harness, Harness Extra, Marksman, Prowl, Shotgun, Surpass, and TopNotch. It may also be applied sequentially after several preeemergence herbicides. Consult the section for each product. Do not tank-mix with Accent Gold, Basis, Basis Gold, Hornet, Python, or Steadfast.
Ignite 280 (glufosinate) may only be applied postemergence to Liberty Link corn. Provides broad spectrum grass and broadleaf weed control. Relative to glyphosate in Roundup Ready corn, weed control from Ignite may be reduced slightly more by adverse weather conditions, such as drought or cool temperatures. Also, coverage is more important for Ignite as the recommended carrier rate is 15 gpa for ground applications or 10 gpa for aerial applications. Do not use nitrogen solutions as spray carriers. Do not use nozzles or pressures that result in coarse spray droplets. Add AMS at 3 lb/A (or 17 lb per 100 gallons). Reduce AMS rate to 1.5 oz/A (8.5 lb per 100 gallons) when temperatures exceed 85o F. Additional surfactants or crop oils may increase the chance of corn injury.
Applying a preemergence herbicide is recommended to reduce weed competition. May make up to two Ignite applications per growing season totaling 44 oz/A. Sequential applications should be made 10-14 days apart. If Ignite was applied as a burndown treatment, do not apply Ignite postemergence. Do not apply to corn stressed from weather conditions, such as drought, excessive rainfall, etc. For best results, apply when weeds are actively growing. Heavy dew or fog may reduce efficacy. Rainfast within 4 hours after application. Apply between dawn and 2 hours before sunset.
Several tank-mix options, such as atrazine, residual grass herbicides (pendimethalin, acetochlor, metolachlor, Guardsman Max), growth regulator herbicides (2,4-D, Status, Distinct), HPPD-inhibiting or “bleacher” herbicides (Laudis, Impact, Callisto), ALSinhibiting herbicides (nicosulfuron, Python, Permit, Yukon, Spirit), and others (see label).
PPS. May be applied prior to planting conventional or transgenic corn. Apply a minimum of 29 fl oz/A. Postemergence applications are not allowed in fields treated with a preplant or preemergence application of Ignite.
38 www.iGrow.org POST. Apply from emergence up to V5 corn (5-leaf collars). Generally, apply to weeds 3-8 inches tall, but check the label for specific species height restrictions. Do not apply more than two 22 oz/A applications per year. Wait 10-14 days between applications. Do not apply within 60 days of harvesting corn for forage or within 70 days of harvesting for grain.