Table 2.4-4. Characteristics of preplant or preemergence soybean herbicides
| Herbicide¹ | Family | Mode of Action | Site of Action | Injury Symptoms | Weeds Controlled | Residual² | Potential Problems |
|---|---|---|---|---|---|---|---|
|
|||||||
| Authority / Spartan (sulfentrazone) | Aryl Triazolinone | Cell membrane disrupter | PPO | Stunted growth, yellowing, seedling death | Annual broadleaves | M-L | Lack of rain to activate; emerged weeds at application |
| Axiom (flufenacet + metribuzin) | Oxyacetamide + triazine | Seedling growth inhibitor + photosynthesis inhibitor | Multiple + D-1 quinone protein | Heart-shaped unifoliate leaves; looping of grass seedlings; interveinal yellowin | Annual grasses and broadleaves | M | Lack of rain to activate; emerged weeds at time of application; triazine-resistant weeds; crop injury due to adverse environment |
| Canopy (chlorimuron + metribuzin) | Sulfonylurea + triazine | Amino acid biosynthesis inhibitor (protein) + photosynthesis inhibitor | ALS synthase + D-1 quinone protein | Interveinal yellowing and necrosis of older leaves; stunting | Annual broadleaves | L | Lack of rain to activate, high pH soils leading to carryover |
| Command (clomazone) | Isoxazolidinones | Pigment inhibitor | Cartenoid biosynthesis | Chlorotic; whitened plant tissue | Annual broadleaves and grasses | L | Insufficient application rate; uneven incorporation |
| Dual / Cinch (metolachlor) | Chloroacetamide | Seedling growth inhibitor (shoot) | Multiple | Heart-shaped unifoliate leaves; looping of grass seedlings | Annual grasses and certain broadleaves | M | Lack of rain to activate; emerged weeds at application; tolerant species |
Intro (alachlor) |
Chloroacctamide |
Seedling growth inhibtor (shoot) |
Multiple |
Heart-shaped unifoliate leaves; looping of grass seedlings |
Annual grasses and certain broadleaves |
M |
Lack of rain to activate; emerged weeds at application; tolerant species |
| Lorox (linuron) | Urea | Photosynthesis inhibitor | D-1 quinone protein | Interveinal yellowing and necrosis of older leaves | Annual broadleaves | M | Lack of rain to activate; tolerant weeds |
Metribuzin |
Triazine |
Photosynthesis inhibitor |
D-1 quinone protein |
Interveinal yellowing and necrosis of older leaves |
Annual broadleaves |
M |
Triazine-resistant weeds, crop injury due to adverse environment; lack of rain to activate |
| Outlook (dimethenamide) | Chloroacetamide | Seedling growth inhibitor (shoot) | Multiple | Looping of grass leaves at emergence | Annual grasses and certain broadleaves | M | Lack of rain to activate surface applications; emerged weeds at time of application, tolerant species |
| Prowl (pendimethalin) | Dinitroaniline | Seedling growth inhibitor (root) | Tubulin protein | Swollen roots; stunted growth; swollen, brittle stem with surface application of | Annual grasses and certain broadleaves | M-L | Poor incorporation; lack of rain with surface-applied Prowl; tolerant species |
| Pursuit (imazethapyr) | Imidazolinone | Amino acid biosynthesis inhibitor (protein) | ALS synthase | Stunted growth; purple foliage; inhibited root growth | Annual broadleaves, some grasses | L | Weeds too large or hardened-off; tolerant weeds |
| Python (flumetsulam) or FirstRate (cloransulam) | Sulfonamide | Amino acid biosynthesis inhibitor (protein) | ALS synthase | Prevents true leaf emergence; stunted growth, chlorosis, or purpling | Annual broadleaves | M-L | Lack of rainfall to activate; in-furrow insecticide application, high soil pH, and/or sandy-gravelly soils leading to crop injury |
| Scepter (imazaquin) | Imidazolinone | Amino acid biosynthesis inhibitor (protein) | ALS synthase | Stunted growth; purple foliage; inhibited root growth | Annual broadleaves | L | Lack of rain to activate; tolerant weeds |
| Sencor (metribuzin) | Triazine | Photosynthesis inhibitor | D-1 quinone | Interveinal yellowing and necrosis of older leaves | Annual broadleaves | M | Triazine-resistant weeds, crop injury due to adverse environment; lack of rain to activate |
| Sharpen (saflufenacil) | Pyrimidinedione | Cell membrane disrupter | PPO | Foliar burning | Annual broadleaves | S-M | Lack or rainfall, weeds too large at burndown |
| Treflan (trifluralin) | Dinitroaniline | Seeding growth inhibitor (root) | Tubulin protein | Swollen roots; stunted growth; swollen hypocotyl | Annual grasses and certain broadleaves | M-L | Poor incorporation; tolerant species |
