Barricade 4FL Pre-Emergent Herbicide (Prodiamine)

Barricade 4FL is a professional pre-emergent herbicide containing prodiamine that helps prevent crabgrass, annual bluegrass (Poa annua), and many other grassy and broadleaf weeds from becoming established. Ideal for spring and fall pre-emergent applications, Barricade 4FL can be used on many warm- and cool-season turfgrasses and must be applied before target weeds germinate for effective weed prevention.

When is the best time to apply Barricade 4FL Pre-Emergent Herbicide?

Barricade 4FL should be applied before target weeds germinate, making application timing one of the most important factors for successful weed prevention. For most lawns, this means making pre-emergent applications in spring and/or fall, depending on the weeds you need to prevent.

• Spring application: Apply after the ground has thawed but before soil temperatures consistently reach about 55°F, when crabgrass begins germinating. Other summer annual weeds may begin germinating as soil temperatures rise into the 55–65°F range.
• Fall application: Apply before winter annual weeds germinate. A general application window is August through November, when soil temperatures are below about 70°F and declining.
• Apply before germination: Barricade 4FL is a pre-emergent weed killer and will not control weeds that are already established.
• Adjust for your location: The ideal application date varies by climate and local soil temperatures, so monitor soil temperatures rather than relying only on a calendar date.

For season-long weed prevention, always follow the Barricade 4FL product label for application rates, annual maximums, and timing for your turf species.

What grass types can Barricade 4FL pre-emergent herbicide be applied to?

Barricade 4FL can be used on many established warm-season and cool-season turfgrasses when applied according to the product label.

Labeled turf includes:

• Bermudagrass
• St. Augustinegrass
• Zoysiagrass
• Centipedegrass
• Bahiagrass
• Buffalograss
• Seashore paspalum
• Tall fescue
• Fine fescue
• Perennial ryegrass
• Kentucky bluegrass

Application rates vary by turf species. In general, Barricade 4FL rates range from 0.5–1.1 fl oz per 1,000 sq ft for warm-season grasses and 0.23–0.70 fl oz per 1,000 sq ft for most cool-season grasses. Always use the rate specified on the product label for your turfgrass and target weeds.

What weeds does Barricade 4FL prevent?

Barricade 4FL is a prodiamine pre-emergent herbicide that prevents more than 30 grassy and broadleaf weeds when applied before weed seeds germinate.

Common weeds controlled or suppressed include:

• Crabgrass, including large and smooth crabgrass
• Goosegrass
• Annual bluegrass (Poa annua)
• Foxtails
• Barnyardgrass
• Witchgrass
• Chickweed
• Spurge
• Common purslane
• Other annual grassy and broadleaf weeds listed on the product label

Important: Barricade 4FL prevents susceptible weeds from becoming established; it does not kill existing weeds. If weeds have already emerged, a compatible post-emergent herbicide may be needed.

What is the Barricade 4FL mix rate per gallon of water?

There is not one universal Barricade 4FL mix rate per gallon because the correct amount of herbicide is based on the area being treated, turf species, target weed, and application rate, rather than the amount of water in your sprayer.

Barricade 4FL application rates generally range from 0.23–1.1 fl oz per 1,000 sq ft, depending on the turfgrass and application.

To determine how much Barricade 4FL to mix in a 1-gallon sprayer:

1. Check the label to find the Barricade 4FL rate per 1,000 sq ft for your turf and application.
2. Calibrate your sprayer to determine how much water you personally use to evenly cover 1,000 sq ft.
3. Add the required amount of Barricade 4FL for that 1,000 sq ft to the amount of water your sprayer uses to cover it.

Example: If your sprayer uses 1 gallon of water to cover 1,000 sq ft and your selected label rate is 0.80 fl oz per 1,000 sq ft, mix 0.80 fl oz of Barricade 4FL in the 1 gallon of water.

For larger applications, the label also lists a rate of 21 fl oz per 25 gallons of water per acre. Always follow the product label for the exact rate required for your application.

Does Barricade 4FL need to be watered in after application?

Yes. Barricade 4FL should be watered into the soil after application so the prodiamine can form the pre-emergent barrier needed to prevent weed seedlings from becoming established.

• Water the pre-emergent treatment in as soon as practical after application.
• Barricade 4FL can be watered in by irrigation or rainfall.
• Approximately 1/2 inch of water is sufficient to activate the treatment.
• Ideally, activation occurs soon after application, although watering can occur within 7 days.
• Avoid excessive irrigation or heavy rainfall that could cause runoff or uneven distribution.

Once activated in the soil, Barricade provides residual pre-emergent weed control when applied according to label directions.

Can I apply Barricade 4FL before it rains?

Yes. Applying Barricade 4FL before light to moderate rainfall can be an effective way to water the pre-emergent herbicide into the soil.

Plan for enough rainfall to activate the product without creating runoff. Approximately 1/2 inch of water is needed. Avoid applying immediately before unusually heavy rain that could cause runoff or move the herbicide away from the intended treatment area.

Barricade 4FL can also generally be applied after a light rain if the soil is able to absorb additional moisture and is not saturated.

How does Barricade 4FL pre-emergent herbicide work?

Barricade 4FL contains 40.7% prodiamine, a Group 3 pre-emergent herbicide. When applied and activated in the soil before weed germination, it creates a residual herbicide barrier that inhibits the development of susceptible weed seedlings.

This makes Barricade 4FL best suited for preventive weed control rather than treating weeds you can already see.

For the best results:

• Apply before target weeds germinate.
• Use the correct rate for your turf and target weeds.
• Apply uniformly across the treatment area.
• Water the application into the soil as directed.
• Use an appropriate post-emergent herbicide separately or as a labeled tank mix when existing weeds also need to be controlled.

Can Barricade 4FL be used on existing weeds?

No. Barricade 4FL is primarily a pre-emergent weed preventer and will not control established weeds that have already emerged.

For lawns with both existing weeds and weeds that have not yet germinated, Barricade 4FL may be tank mixed with certain compatible post-emergent herbicides when permitted by both product labels. Follow all rates, turf restrictions, and application directions on each label.

Can I seed or overseed after applying Barricade 4FL pre-emergent?

Barricade 4FL can also prevent desirable grass seed from successfully establishing, so do not seed or overseed too soon after an application.

As a general rule, avoid overseeding within 4 months of applying Barricade 4FL. The exact reseeding interval can vary with the application rate, turf species, and other conditions, so check the product label before planning a Barricade application if you intend to seed or overseed your lawn.

If fall overseeding is part of your lawn-care program, plan your spring pre-emergent rate and timing accordingly.

How long does Barricade 4FL last?

Barricade 4FL is designed to provide long-lasting, season-long pre-emergent weed control when applied at the appropriate rate and timing.

How long the treatment remains effective depends on factors such as:

• Application rate
• Target weed
• Turf species
• Application timing
• Soil and environmental conditions

Do not exceed the maximum annual application rate listed for your turf species. Refer to the product label when planning single or split pre-emergent applications.

Can Barricade 4FL be used around flowers, shrubs, and ornamental plants?

Yes. In addition to turf, Barricade 4FL is labeled for use in container-grown, field-grown, and landscape ornamentals, as well as perennial and wildflower plantings and other labeled sites.

For bulbs and certain ornamental plantings, applications may be made according to label directions before weeds emerge. Always confirm that your specific plants and use site are permitted by the label before treating.

Do not apply Barricade 4FL directly to edible plants such as fruits or vegetables unless that use is specifically permitted by the product label.