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Crop and Pest Management Guidelines

A Cornell Cooperative Extension Publication
Skip Navigation LinksHome > Cornell Guidelines > 2024 Trees and Shrubs Table of Contents > 4 Weed Management in Nursery Crops > 4.8 Description and Characteristics of Herbicides Registered for Nursery and Landscape Use > Diquat SPC 2L
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Diquat SPC 2L

Common Name: diquat dibromide

Formulation: 2L

Uses: Nonselective postemergence weed control for use in field and container nurseries, landscape, beds, walkways, patios, beneath greenhouse benches, along driveways, and other non-crop areas. Rapid burn-down of weeds with no soil residual. Cool weather does not reduce the efficacy of *Diquat SPC 2L as drastically as other postemergence herbicides. For this reason, *Diquat SPC 2L is often used in the winter and early spring to control winter annual weeds.

Amount of active ingredient

Amount by formulation

2L

Per Acre

0.25 to 0.5 lb.

1.0 to 2.0 pt.

Per 1,000 sq. ft.

0.75 fl. oz./gal. water

NOTE: as of 2021, Diquat SPC 2L is no longer a restricted use herbicide.

In New York State, aquatic use requires Special Local Needs (SLN) labeling. For products with SLN labeling, all precautionary statements, applicable use directions, precautions, and limitations of the SLN and primary product labeling must be followed.

Major Weeds Controlled: Nonselective postemergence control of seedling broadleaves and grasses.

Major Weeds Not Controlled: Weeds that emerge after application.

For Best Results: Apply for full coverage and thorough weed contact in a minimum of 15 gallons of spray per acre. Higher spray volumes have provided more consistent weed control. Best control is achieved if weeds are young when treated. Re-treatment may be necessary for grasses and established weeds. Note label requirements for use of nonionic surfactant.

Cautions and Precautions: Avoid spray contact with desirable vegetation.

Residual Activity: None

Volatility and Leaching Potential: Nonvolatile. Strongly adsorbed by clay particles in the soil; little leaching expected.

Symptoms and Mode of Action: Interacts with light to produce superoxides that destroy plant cells. On sunny days, treated tissue will appear water soaked within hours. Necrosis follows within one or two days. Dead tissue usually turns black.

Manufacturer: Nufarm

EPA Reg. No: 228-675