Preplant and Preemergence Weed Control

carfentrazone (Aim EC)

Rate 0.008 to 0.031 lb ai/a (0.5 to 2 fl oz Aim EC)

Time Apply before, during, or after grain has been planted.

Remarks May be applied as a preplant burndown (up to 1 day before seeding), foliar broadcast or as a harvest-aid. Use a nonionic surfactant (NIS) at 0.25% v/v (2 pints/100 gal spray solution) having at least 80% active ingredient. A high-quality sprayable liquid nitrogen fertilizer may be used at 2% to 4% v/v (2 to 4 gal/100 gal spray solution) or ammonium sulfate (AMS) at 2 to 4 lb/a in addition to NIS. Tank-mixtures with other herbicides increase spectrum of control. Apply to actively growing weeds not more than 4 inches tall or rosettes 3 inches in diameter. Thorough coverage is essential for good control. To avoid significant crop response, do not apply within 6 to 8 hours of rain or irrigation or if heavy dew is present. Restricted entry interval (REI) is 12 hours.

Caution Do not use Aim EC with crop oil concentrates (COC,) methylated seed oil (MSO), or silicone-based adjuvants. Do not exceed 0.031 lb ai/a (2 fl oz Aim EC) per crop season. Do not harvest for forage within 7 days after application.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Triazolinone

sulfentrazone + carfentrazone (Spartan Charge)

Rate 0.094 to 0.194 lb ai/a sulfentrazone + 0.010 to 0.021 lb ai/a carfentrazone (3.8 to 7.6 oz Spartan Charge 3.5SE)

Time Apply fall or spring as preplant or preemergence within 3 days after planting.

Remarks This is a 24c SLN registration for Idaho only; to be used for the control of Russian thistle and kochia. Consult label to determine rate for soil pH, percent­age of organic matter, and texture. Consult label for specific crop rotation restrictions. Restricted entry interval (REI) is 12 hours.

Caution Do not exceed 0.28 lb ai (10.2 oz) Spartan Charge per 12-month period. Do not apply after crop emerges or if seedlings are near soil surface. Do not apply on coarse soils with less than 1.5% organic matter and soil pH greater than 7.6. Do not apply to frozen soil. Do not incorporate as this can destroy the herbicide barrier. Do not apply this product to spring wheat fields if this herbicide or additional sulfentrazone-containing products have been previously applied within the same 12-month period.

Site of action Group 14: protoporphyrinogen oxidase (PPO) inhibitor.

Chemical family Triazolinone

pyroxasulfone + carfentrazone (Anthem Flex)

Rate 0.063 to 0.141 lb ai/a (2.0 to 4.5 oz/a Anthem Flex)

Time Apply 30 days preplant through fourth tiller. See label for application timing, soil type, and rate information.

Remarks Apply preplant through preemergence only to soils with a CEC greater than 15, pH less than 7.5, and organic matter greater than 2%. If soils do not meet these requirements, Anthem Flex must be applied as a delayed preemergence or postemergence treatment. Results are best when applied prior to weed emergence. May be applied as a single treatment or sequential treatments. May be applied with other labeled herbicides. For herbicide resistance management, particularly for Italian ryegrass, apply a spring postemergence grass herbicide such as Axial or PowerFlex. Restricted entry interval (REI) is 12 hours.

Caution Wheat must be planted a minimum of 1 inch deep. Do not apply more than a total of 0.031 ai/a of carfentrazone to wheat per year. Must have a minimum of 0.5 inch of rain to activate. Rainfall and/or irrigation needs to be between 48 hours and 7 days after application or weed control may be erratic. Do not apply through any type of irrigation system. Do not apply to frozen or snow-covered ground.

Site of action (pyroxasulfone) Group 15: inhibits very-long-chain fatty acid synthesis; (carfentrazone) Group 14: protoporphyrinogen oxidase inhibitor.

Chemical family (pyroxasulfone) chloroacetamide; (carfentrazone) triazolinone

pyroxasulfone (Zidua)

Rate 0.041 to 0.081 lb ai/a (1.25 to 2.50 fl oz/a Zidua SC) delayed preemergence; 0.057 to 0.130 lb ai/a (1.75 to 4 fl oz/a Zidua SC) early postemergence.

Time Apply delayed preemergence or early postemergence in fall-seeded or spring-seeded wheat. Plant wheat seed 1 to 1.5 inches deep and apply only to a uniform seedbed with good seed row closure and soil coverage.

  • Delayed Preemergence: Apply as a broadcast spray to the soil surface when 80% of germinated wheat seeds have a shoot at least 0.5 inch long until wheat spiking.
  • Early Postemergence: Apply to wheat at spiking up to the fourth-tiller growth stage.

Remarks Applied as pre-plant surface or pre-emergence can cause wheat injury. Activity may be reduced if trash from previous crop covers more than 25% of the soil surface. Must be incorporated with rainfall or irrigation after application for optimal weed control. Crop rotation interval ranges from 1 to 6 months depending on amount of Zidua used (see label for details). Restricted entry interval (REI) is 12 hours.

Caution Do not apply more than a maximum cumulative amount of 4.0 fl oz/a of Zidua (0.130 lb ai/a pyroxasulfone) per cropping season. Do not apply Zidua to durum wheat. Do not apply preplant surface, preplant incorporated, or preemergence in wheat. Do not apply delayed preemergence to broadcast seeded wheat.

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

Chemical family Pyrazole

glyphosate (several trade names)

Rate 0.375 to 0.75 lb ae/a (1 to 2 pt/a of a 3 lb ae/gal formulated herbicide)

Time Apply before, during, or after planting wheat, but before wheat emerges.

Remarks Results are best if a delay between tillage and planting allows weeds to emerge before the wheat. Glyphosate may be used only as a spot-treatment in wheat fields. Do not treat more than 10% of the field to be harvested. Be aware that glyphosate is formulated as 3 lb, 4 lb, 4.2 lb, 4.5 lb, and 5 lb ae/gal; be sure to use the correct amount of herbicide depending on the formulation. Some glyphosate products require adding a nonionic surfactant (NIS); check the label. The addition of 1 to 2% ammonium sulfate (AMS) by weight or 8.5 to 17 lb/100 gal spray solution may increase the performance of glyphosate particularly with hard water or spraying during drought conditions. Restricted entry interval (REI) is 4 hours.

Caution Carefully check the entire field to ensure that wheat has not begun to emerge. Do not allow glyphosate to drift off target. Do not apply glyphosate through any irrigation system.

Site of action Group 9: inhibits EPSP synthase

Chemical family Organophosphorus

paraquat (Gramoxone Inteon)

Rate 0.25 to 1 lb ai/a (2 to 4 pints/a Gramoxone Inteon 2SL)

Time Apply before, during, or after planting wheat but before wheat emerges and when weeds are actively growing and 1 to 6 inches tall.

Remarks It is essential to obtain complete coverage of target weeds to get good control. Results are best if a delay between tillage and planting allows weeds to emerge. Controls only annual weeds. Weeds 1 to 6 inches in height are the easiest to control. Always use a nonionic surfactant (NIS) at a minimum of 0.125% v/v (1 pint/100 gal spray solution); crop oil concentrate (COC) or methylated seed oil (MSO) containing 15 to 20% approved emulsifier at 1% v/v (1 gal/100 gal spray solution) with the application. Restricted entry interval (REI) is 24 hours.

Caution A restricted-use herbicide. Do not mix or store in containers, spray tanks, nurse tanks or such systems made of aluminum or having aluminum fittings. May be fatal if swallowed or inhaled. See label for correct protective equipment. Applicators, mixers and loaders must wear long-sleeve shirt and long pants, shoes plus socks, protective eyewear (applicator), face shield (mixers and loaders), Category A chemical resistant gloves, chemical resistant apron (mixers and loaders), and a dust mist NIOSH-approved respirator with an N, R, P, or HE filter. Dry, dusty conditions will decrease herbicide's activity. Do not apply if wheat has already emerged.

Site of action Group 22: photosystem I electron diversion

Chemical family Bipyridilium