Pest Control
Tank-Mixing Acclaim Extra Herbicide With Lawn Fertilizers
The Intersection of Soil Nutrition and Grassy Weed Control
Managing grassy weeds like crabgrass, goosegrass, and barnyardgrass in cool-season turf requires precise timing, especially when coordinating with your lawn's fertilization schedule. Acclaim Extra herbicide (active ingredient: fenoxaprop-P-ethyl) is a premier post-emergent option for Kentucky bluegrass, tall fescue, perennial ryegrass, and fine fescue. However, integrating this herbicide with liquid soil nutrition programs introduces complex chemical and biological variables.
Weeds growing in nutrient-rich, well-fertilized soil are actively translocating sugars and amino acids to their root zones. This vigorous growth phase actually enhances the efficacy of post-emergent herbicides, as the plant rapidly pulls the fenoxaprop-P-ethyl down to the crown and roots. Conversely, applying high-nitrogen liquid fertilizers simultaneously with herbicides can trigger severe phytotoxicity if environmental conditions are not strictly managed. This guide details the exact protocols for tank-mixing Acclaim Extra with liquid fertilizers, biostimulants, and micronutrients without compromising turf health or herbicide performance.
Acclaim Extra: Core Specifications
- Active Ingredient: Fenoxaprop-P-ethyl (0.73 lbs/gal)
- Target Weeds: Annual and perennial grassy weeds (crabgrass, goosegrass, barnyardgrass, annual bluegrass)
- Safe Turfgrasses: Kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue, creeping bentgrass (golf courses only)
- Standard Application Rate: 0.8 to 1.2 fl oz per 1,000 sq ft (35 to 52 fl oz per acre)
- 2026 Market Pricing: Approximately $210 to $230 per 2.5-gallon jug (translating to roughly $1.80 to $2.20 per 1,000 sq ft)
Tank-Mixing Acclaim Extra with Liquid Fertilizers
Lawn care professionals and advanced homeowners frequently utilize liquid fertilizers—such as Urea Ammonium Nitrate (UAN), chelated iron, and kelp-based biostimulants—to deliver rapid foliar nutrition. While Acclaim Extra can be tank-mixed with many of these products, the chemical interactions dictate strict compatibility rules. According to turfgrass researchers at the Penn State Extension Turfgrass Program, improper tank-mixing of post-emergent grassy weed controls with high-salt liquid nitrogen sources can cause severe leaf burn on tall fescue and perennial ryegrass.
| Fertilizer / Additive Type | Compatibility | Operational Notes & Restrictions |
|---|---|---|
| UAN (28% or 32% Nitrogen) | Conditional | Acts as a mild adjuvant, increasing herbicide uptake. Do not exceed 1 gallon of UAN per acre. Avoid application when air temperatures exceed 80°F to prevent severe foliar burn. |
| Chelated Iron (Fe-EDDHA) | Compatible | Iron solutions can lower spray tank pH. If pH drops below 4.5, fenoxaprop efficacy may degrade. Add a phosphate buffering agent to maintain a pH between 5.5 and 6.5. |
| Kelp / Amino Acid Biostimulants | Highly Compatible | Excellent tank-mix partner. Biostimulants help mitigate turf stress from the herbicide and promote rapid lateral recovery of the desired cool-season grass. |
| Broadleaf Herbicides (2,4-D, Triclopyr) | Incompatible | Causes severe antagonism. The broadleaf herbicide will rapidly reduce the grassy weed control efficacy of Acclaim Extra. Apply at least 5 to 7 days apart. |
Step-by-Step Application Protocol for Fertilized Lawns
To achieve optimal grassy weed control while delivering foliar nutrition, the physical mixing order in your spray tank is non-negotiable. Acclaim Extra is formulated as an Emulsifiable Concentrate (EC). Liquid fertilizers are generally true Solutions. Following the industry-standard WALES mixing sequence prevents the herbicide from 'oiling out' or separating in the tank.
The WALES Mixing Sequence
- Wettable Powders (W): If adding any dry flowables or wettable powders (rare in this specific mix, but applicable if adding certain fungicides), add them first to a half-full tank of water.
- Agitate (A): Turn on mechanical agitation or shake the backpack sprayer thoroughly.
- Liquid Flowables (L): Add any suspension concentrates (SC).
- Emulsifiable Concentrates (E): Add the Acclaim Extra herbicide at the prescribed rate (0.8 to 1.2 fl oz per 1,000 sq ft).
- Solutions & Surfactants (S): Add your liquid fertilizer (e.g., kelp, UAN), followed lastly by the required surfactant. Acclaim Extra requires a Methylated Seed Oil (MSO) at 1 to 2 pints per 100 gallons, or a high-quality Non-Ionic Surfactant (NIS) at 2 to 4 pints per 100 gallons.
Pro Tip: Always use a minimum water volume of 1.5 to 2.0 gallons per 1,000 square feet. Higher water volumes ensure the fenoxaprop-P-ethyl and the liquid fertilizer are distributed evenly across the leaf surface, reducing the localized concentration that causes leaf tip burn.
Troubleshooting Phytotoxicity and Herbicide Antagonism
When combining soil nutrition and pest control, failure modes usually manifest as either turf phytotoxicity or weed control failure. Data from NC State University TurfFiles highlights that environmental stress is the primary catalyst for negative interactions.
Warning: The High-Nitrogen Heat Trap
Applying Acclaim Extra tank-mixed with liquid nitrogen (UAN) during late summer heat waves is a common mistake. The high salt index of the UAN draws moisture out of the turfgrass leaf cells. Simultaneously, the EC formulation of the herbicide and the MSO surfactant strip the leaf cuticle's waxy protective layer. The result is severe desiccation and necrosis of tall fescue and perennial ryegrass within 48 hours. Restrict UAN tank-mixes to spring and early fall when daytime highs are consistently below 80°F.
Antagonism with Starter Fertilizers: Acclaim Extra is one of the few post-emergent herbicides safe for use on newly seeded cool-season lawns (once the new grass has been mowed twice). Homeowners often apply high-phosphorus granular starter fertilizers at the time of seeding. Granular fertilizers do not cause chemical antagonism in the spray tank, but excessive nitrogen from the starter fertilizer can cause the newly germinated crabgrass to grow too rapidly, developing thick, mature cuticles before the herbicide is applied. For best results, apply Acclaim Extra when grassy weeds are young and actively tillering (1 to 3 leaves), regardless of the granular fertilizer schedule.
Frequently Asked Questions
Can I mix Acclaim Extra with granular fertilizer in a spreader?
No. Acclaim Extra is a liquid post-emergent herbicide and must be applied via a sprayer. However, you can apply granular fertilizer on the same day. Best practice dictates applying the granular fertilizer first, watering it in lightly, and then allowing the grass blades to dry completely before spraying the Acclaim Extra mixture to prevent dilution of the herbicide on the leaf surface.
Does liquid iron improve Acclaim Extra efficacy?
Liquid iron does not chemically enhance the herbicidal activity of fenoxaprop-P-ethyl. However, it provides a cosmetic benefit. While the Acclaim Extra slowly kills the crabgrass or goosegrass over 10 to 14 days, the liquid iron darkens the surrounding desirable Kentucky bluegrass or fescue, masking the visual presence of the dying weeds and improving the lawn's immediate aesthetic appeal.
How long should I wait to fertilize after spraying Acclaim Extra?
If you are using a standard granular slow-release nitrogen fertilizer, you can apply it immediately after the Acclaim Extra spray has dried (usually 2 to 4 hours). If you are using a liquid foliar fertilizer containing high salts or penetrating surfactants, wait at least 48 hours to allow the herbicide to fully translocate into the weed's root system without being washed off or chemically altered on the leaf surface.
