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Below, we've answered your most common questions regarding Sonic® herbicide. If you have additional questions, please submit them below. 

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Answers to Your Questions About Sonic® Herbicide

If you have additional questions, please submit them below.

What is the residual control with Sonic® herbicide?

Sonic® herbicide offers two nonglyphosate modes of action to provide long-lasting residual control. Taking advantage of this preemergence herbicide to control weeds early can help farmers' time, obtain better full-season control and protect more yield.

Sonic herbicide has a labeled application rate of 4 to 7 ounces per acre. The length of residual will depend greatly on where your application falls within that rate spectrum. If you apply 4 ounces per acre, you can expect residual control to last between four and six weeks. From there, you generally can expect an additional seven to 10 days of control for every ounce per acre that the application rate increases. So, at the maximum rate of 7 ounces per acre, we’ve seen seven to 10 weeks of residual control when applied as a preemergence. One benefit of that long-lasting residual control is that it gives farmers a much wider window in which to make postemergence applications. It also keeps those later-season weeds small and easier to control so you can stay on label with any postemergence treatments. 

Of course, the amount of moisture received after the application is made, as well as the soil type being applied to, both can factor into the duration of residual control experienced. 

How effective is Sonic® herbicide to ALS-resistant weeds?

Sonic® herbicide is powered by two modes of action, attacking weeds multiple ways to effectively manage herbicide resistance and protect yield potential. It provides residual control on a broad spectrum of weeds, offering the flexibility to be applied preemergence up to three days postplant.

Is Sonic® tank-mix compatible with other herbicides?

Sonic® is tank-mix-compatible with many other herbicides. For additional information on Sonic and the tank-mix compatibility, read the product label.

Yes, we recommend adding Elevore® herbicide to a tank mix with Sonic® or Surveil® herbicides. Elevore can also be applied with commonly used residual and burndown herbicides, including 2,4-D and glyphosate, up to 14 days before planting soybeans or corn.

Elevore contains Arylexactive, a Group 4 growth regulator that acts through a synthetic auxin mechanism to control broadleaf weeds in burndown. Although Arylex active is not considered a new mode of action, it does have unique binding affinity that is different from other auxin herbicides such as 2,4-D.

The low use rate of 1 ounce per acre makes Elevore an excellent fit in reduced- and no-till systems. Elevore helps your customers control a full-range of broadleaf weeds, including emerged marestail up to 8-inches-tall, henbit, purple deadnettle, common ragweed and lambsquarters.

What’s the best approach to control waterhemp and marestail in soybeans?

Resistant waterhemp and marestail can cause anxiety for any farmer. Fortunately, there are some specific tips when looking to control these two resistant weeds:

  • Start with a clean seedbed. For marestail specifically, apply a burndown herbicide to control it early.

  • In spring, apply a residual herbicide, such as Sonic® herbicide, for an additional layer of early season control.

  • Scout fields to determine postemergence approach.

What are the benefits of using Sonic® for fall weed control?

Taking action against weeds in the fall can pay big dividends in the spring. That’s because controlling actively growing fall weeds can eliminate the need for, or increase the effectiveness of, any spring burndown herbicide program.

Using Sonic® herbicide has five big benefits to fall weed control. Sonic:

  • Allows for spraying on actively germinating weeds when control is most effective.
  • Spreads out workload, giving farmers greater flexibility in the spring.
  • Decreases weed competition to maximize the yield potential of emerging soybeans.
  • Optimizes timing of spring applications to be made on smaller, more uniform-sized weeds.
  • Is easy to handle and mixes well with other herbicides for broad-spectrum control.


When considering application timing, you should always refer to the product label of the herbicide or herbicides that you are planning to apply. Many herbicides labeled for fall application may include restrictions on treatments made to frozen soil or in freezing temperatures. The label for Sonic does not include any specific cold-weather restrictions. However, as a general rule of thumb, it can be more difficult to get consistent performance in colder temperatures. The selected mode(s) of action of the herbicide being fall-applied will have an impact on effectiveness. 

Otherwise, there are a couple of key indicators to take into account when deciding if there is still time to make a fall herbicide application. Check to see if the ground is frozen. If it is, it’s too late. If it’s not, take a look at current air temperatures. Ideally, you want daytime temperatures to be climbing at the time of application and reach the mid- to upper 50s. Also, the overnight lows should be consistently above freezing, but ideally staying around 40 F to achieve better performance.


How much rain does it take to activate Sonic® herbicide?

Rainfall is needed for any herbicide to take effect in the soil for controlling weeds. The timeliness of needed rainfall partly depends on the soil temperature following application.

When soil conditions are cooler, weeds aren’t germinating as quickly, which gives you a little more time to receive rainfall. Under normal conditions, receiving rainfall within seven to 10 days is ideal. If it’s extremely warm and it’s a late-spring application, an activating rain within three to four days will provide optimum performance. 

How close to planting can I apply Sonic® herbicide?

Sonic® herbicide can be applied pre-plant incorporated, preplant or preemergence up to three days after planting before soybeans emerge. Sonic can also be applied in the fall to control winter and early spring annual weeds. 

Both preemergence and early preplant are great options for making an application of Sonic herbicide. One of the most valuable features of Sonic is that it’s flexible enough to enable farmers to use it in the manner that best fits the way they farm. For many, the popular choice is to plant soybeans and then apply Sonic within three days or prior to cracking. In certain conditions, this application timing window can be a bit tight. Preplant applications allow more time and can be done in conjunction with a burndown application. This allows growers to plant whenever the field is fit. 

How does the use of Sonic® herbicide affect cover crops and rotation?

First, it’s imperative to carefully read all herbicide product labels. This will determine if desired fall-seeded crops are listed in the included rotational crop guidelines. These guidelines, generated from research data, provide fixed intervals to determine follow-crop sensitivities under varying environmental and soil conditions. They also take into consideration residue levels of both parent and metabolite compounds, which may be taken up by rotational crops and thereby enter the food or feed channel. 

Sonic® herbicide provides highly effective, soil-residual control across a broad spectrum of weeds. The positive attributes of residual weed activity directly imply the active ingredients (in the case of Sonic, sulfentrazone + cloransulam-methyl) may persist for some time. This is at levels that may be injurious to sensitive rotational crops (fall- or spring-seeded). It’s vital for growers to adhere to the minimum intervals listed in the rotational crop interval table of the product label. 

Using Sonic as an example, wheat (at four months) would be the only crop listed on the rotational interval table that would meet the minimum rotation interval for immediate seeding following soybean harvest. This isn’t unique to Sonic, as you’ll find that most commonly used broad-spectrum herbicides list rotational intervals restricting almost all fall-seeded crops. 

We are facing challenging weed control problems. It’s critical that growers carefully weigh the pros and cons of selecting weed control products based on fall-seeded rotational crop flexibility over optimizing in-crop control of yield-robbing weeds.

What sets Sonic® herbicide apart for fighting glyphosate-resistant weeds?

Sonic® is a preemergence, residual herbicide that has been proven to provide consistent control of a broad spectrum of high-anxiety weeds. With two nonglyphosate modes of action, Sonic controls most broadleaf weeds that are resistant to glyphosate, including waterhemp, Palmer amaranth, giant ragweed and common ragweed. Plus, Sonic demonstrates excellent control of morningglory, which is another tough weed for soybean farmers to control with glyphosate alone.

Another reason farmers and retailers choose Sonic® is because of crop safety. Sonic herbicide exhibits outstanding crop safety, which is one less thing for farmers and custom applicators to worry about.

Finally, Sonic is a stable performer in a variety of soil types, including fields with slightly delayed activating rains. Sonic offers a flexible rate range from 4 to 6 ounces when applied in the fall, spring or up to three days postplanting.

How effective is Sonic® herbicide on high-residue no-till?

Sonic® herbicide provides excellent broad-spectrum control of large- and small-seeded broadleaf weeds in conventional, minimum and no-till situations. Sonic is effective in all tillage systems and mixes well with burndown herbicides to manage workloads and reduce weather variability.

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Battle Weeds

Sonic® herbicide is proven to deliver long-lasting, broad-spectrum control to prevent weeds from invading soybean fields.

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To learn more about Sonic® herbicide and the full line-up of soybean herbicides, visit the soybean herbicides portfolio page.

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Sonic® and Elevore® are not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Arylex is a registered active ingredient. Always read and follow label directions.