Prodiamine 65 WDG vs. 4L (Barricade Comparison)
Barricade 65 WDG and Barricade 4L contain the same pre-emergent active ingredient, prodiamine, but they are different formulations. 65 WDG is a water-dispersible granule; 4L is a flowable liquid. Choose by the exact product label, site, and ease of handling. Convert rates by active ingredient, never by equal product weight or volume.
The must-have check before choosing is not which container looks easier to use. It is whether that exact product label allows the treatment on your turf, for the weeds you want to prevent, at the planned rate and time. A rate that is suitable for one site or turf type may not be allowed for another.
I have seen small differences in mixing habits create big differences across a lawn: one section receives steady coverage, while another gets skips or overlap. With prodiamine, careful measuring matters because it creates a barrier in the soil that can also block desirable turf seed from growing.
Product Selection, Label Compatibility & Safety Preparation
Barricade 65 WDG and 4L are pre-emergent herbicides. “Pre-emergent” means they help stop listed weeds as they germinate, rather than killing weeds that are already growing. The active ingredient in both is prodiamine, but the product concentration and form differ, so the labels guide the choice and use.
| Feature | Barricade 65 WDG | Barricade 4L |
|---|---|---|
| Formulation | Water-dispersible granule | Flowable liquid |
| Prodiamine concentration | 65% by weight | 4 lb per U.S. gallon |
| How to measure | Product weight | Liquid volume |
| Mixing need | Disperse granules and keep mixture moving | Keep flowable product uniformly suspended |
| Key caution | Do not assume granules fully dissolve | Do not assume liquid remains mixed without agitation |
Both products are intended for label-listed sites and weeds. Neither is a general-purpose substitute for the other. Check the exact container label and registration, since allowed turf species, sites, rates, tank mixes, and use limits can differ by product and label version.
Before treatment, confirm:
- The site and turf species are listed.
- The target weed and application timing are covered.
- The rate fits the label and annual maximum.
- Any plans to seed, reseed, or overseed meet the stated interval.
- Weather, water, runoff, and buffer rules allow treatment.
- The label’s personal protective equipment (PPE), re-entry, and other safety directions are clear.
Read the current label and safety data sheet (SDS) before mixing. Keep people and pets away as the label directs. Do not apply to newly seeded or recently established turf unless that exact label permits it. Key takeaway: choose by label fit first, then by the formulation that you can measure and apply accurately.
Rate Conversion, Agitation & Sprayer Maintenance
A rate conversion compares the amount of active ingredient, or “a.i.,” in each product. It helps translate a permitted rate from one formulation to the other, but it does not make the products interchangeable under their labels. Confirm that the resulting product rate is allowed for your site and use.
The theoretical equivalents are:
- 1 lb prodiamine a.i. = about 1.538 lb of 65 WDG.
- 1 lb prodiamine a.i. = 0.25 U.S. gallon, or 32 fluid ounces, of 4L.
These are active-ingredient conversions, not universal application directions. For example, if a label-permitted plan called for 0.5 lb a.i. per acre, the matching product amounts would be about 0.769 lb of 65 WDG or 0.125 gallon (16 fluid ounces) of 4L per acre. This is a math example, not a recommended rate. Check both labels before using a converted amount.
Do not swap equal product amounts. A pound of WDG and a pound of 4L do not contain the same amount of prodiamine. Nor should you treat a fluid ounce as the same as an ounce by weight.
Both formulations need proper agitation. WDG is a granule designed to disperse in water; 4L is a flowable product. Neither should be treated as a fully dissolved solution. Follow the label’s mixing directions and keep the tank moving as directed so product does not settle and cause uneven delivery or block screens and nozzles.
A practical calibration sequence is:
- Measure the treatment area. For irregular areas, divide the space into simple shapes and add their areas.
- Use clean water to test the sprayer over a known area at your normal walking speed and pressure.
- Adjust output so the sprayer applies the label-directed volume evenly across that area.
- Calculate the product needed for the measured area using the label rate and the correct units.
- Mark passes or use a treatment map to avoid overlap and missed strips.
Do not increase the rate to compensate for poor coverage. Key takeaway: measure the area, calibrate with water, convert by active ingredient, and keep the mix agitated.
Calibration, Mixing & Field Application
Calibration sets how much spray the equipment puts on a known area. It helps match the label rate to the area being treated. A calibrated sprayer still needs an even pace, correct mixing, and careful passes; calibration cannot fix overlap, drift, or an unsuitable application day.
Follow the exact label for product order and mixing. In general, prepare only the amount needed for the job, use the label’s stated water volume and mixing order, and agitate as directed. Do not add tank-mix partners unless the label allows the combination.
Apply before the target weeds germinate. Prodiamine does not control weeds that are already established. Some labels require rainfall or irrigation to move the product into the soil. Where the label calls for activation, it commonly specifies at least 0.5 inch within 14 days. Use the exact label’s threshold and timing, and avoid irrigation or application conditions that could cause runoff.
Watch for these common errors:
- Double coverage: A second pass over the same strip can raise the rate beyond the intended amount.
- Unplanned seeding: The barrier can interfere with desirable turf seed. Check the label’s reseeding and overseeding intervals before treatment.
- Poor agitation: Settling can make one part of the lawn receive too much product and another too little.
- Drift or hard-surface spray: Avoid drains, impervious surfaces, and areas where product could move off target.
- Extra “booster” applications: Do not repeat treatment outside the label’s rate and interval limits because results seem weak.
Practical application scenarios
These are planning examples, not reports of measured field trials or product-rate recommendations.
- A broad, open lawn: A 4L product may suit a crew that already uses a liquid sprayer and can keep the tank agitated. Map the passes, calibrate over a known area, and track the amount used.
- A small or irregular lawn: WDG may be easier to weigh if the operator has a suitable scale and can disperse it as directed. Small areas still require accurate measurement; estimating by eye is not a safe shortcut.
- A lawn scheduled for overseeding: Pause and check the label’s interval. If the planned seed date falls inside the restriction, delay treatment or discuss another weed plan with a qualified local professional.
After treatment, irrigate only as directed and when water will not run off. Follow the label for re-entry and equipment cleanup. Key takeaway: accurate, even coverage is more important than choosing a formulation based on convenience alone.
Storage, Cleanup & Seasonal Treatment Planning
Seasonal planning means placing the application before weed germination while protecting the turf you want to keep. It also means checking seed plans, yearly product limits, and the label’s activation and weather rules before the day of treatment. A calendar reminder is useful, but the label and local conditions control the final decision.
Keep the product in its original, closed container and follow label storage directions. Do not leave mixed spray in equipment unless the label permits it. Rinse and clean the sprayer as directed, and handle rinsate only as the label and local rules allow; never dump it into a drain or where it may reach water.
For larger properties, record the product name, formulation, treated area, rate, date, and weather. Keep a simple map of completed passes. These notes help prevent a second application from accidentally crossing an area that has already received its annual limit.
| Before the job | During the job | After the job |
|---|---|---|
| Confirm label, turf, weed, rate, and seed plans | Maintain agitation; follow mapped passes | Follow re-entry and cleanup directions |
| Check annual maximum and local restrictions | Avoid skips, overlap, drift, and runoff | Record product, rate, date, and area |
| Calibrate with clean water | Apply only at the label rate | Store product as directed |
Key takeaway: plan treatment around germination and seeding, not just around a convenient workday.
Frequently Asked Questions
Are Barricade 65 WDG and 4L the same herbicide?
Both contain prodiamine, but they are different formulations with different concentrations and handling needs. Follow the label for the exact product you have.
Can I use the same amount of 65 WDG and 4L?
No. Their concentrations use different units. Convert by pounds of active ingredient per area, then confirm the resulting rate is allowed by the product label.
How much 4L equals 1 lb of prodiamine?
The stated concentration gives a theoretical equivalent of 0.25 U.S. gallon, or 32 fluid ounces, of 4L. This is a conversion, not a treatment recommendation.
How much 65 WDG equals 1 lb of prodiamine?
At 65% prodiamine by weight, the theoretical equivalent is about 1.538 lb of product. Check the exact container label before applying.
Does prodiamine kill weeds that are already growing?
No. It is a pre-emergent herbicide for listed weeds as they germinate. It is not a control for established weeds.
Does the spray tank need agitation?
Yes. Follow the label’s agitation directions for either formulation. The product should remain evenly suspended; do not assume it fully dissolves or stays mixed without movement.
When should I water after application?
Use the exact label’s activation directions. Some labels call for at least 0.5 inch of rain or irrigation within 14 days. Avoid conditions that could cause runoff.
Can I apply it before overseeding?
Only if the label’s overseeding interval allows it. Prodiamine can prevent desirable grass seed from establishing, so check the specific label before scheduling either job.
What should I do if I overlapped a pass?
Do not apply an extra treatment to the area. Record where overlap occurred, avoid further applications there, and check the label or contact a local extension service for guidance.
Can I mix another herbicide or fertilizer with it?
Only when the specific product label allows the tank mix and gives compatible directions. Do not assume that a mix permitted for one formulation is permitted for the other.
Which formulation is better for a small lawn?
Neither is always better. Choose the one you can measure, mix, agitate, and apply evenly while following its label and the site’s restrictions.
(This article was written by one of our staff writers, Victor Dempsey. Visit our Meet the Team page.)
