Corvus Herbicide FAQ

Corvus Product Overview

What is Corvus herbicide?

Corvus® is a pre-emergence corn herbicide. Corvus offers growers three levels of control to fight weeds: burndown, residual and reactivation of control with rain. With almost 10 years of proven performance, Corvus is the No. 1 pre-emergence herbicide brand of choice in the country. 

How does Corvus work?

Corvus goes to work quickly to burndown grass and broadleaf weeds with residual control through canopy closure. Unlike most soil-applied herbicides, Corvus is reactivated by a half-inch of rain, even after a dry period. This unique feature makes Corvus less sensitive to the random and sporadic nature of spring precipitation and provides a better opportunity for Corvus to control weeds up to 2 inches tall in early season corn.

Corvus Product Specs

What is the site of action in Corvus?

Corvus herbicide combines the strength of two sites of action to take down weeds. The first, Group 27, commonly known as a bleacher, inhibits the 4-hydroxyphenylpyruvate dioxygenase (HPPD) enzyme, which is key to the production of pigments and development of chloroplasts in plant tissues. By inhibiting pigment and chloroplast biosynthesis, emerging plant tissue is bleached from green to white or pale yellow and ultimately dies. These symptoms often appear after a half-inch or more of rain on weeds that emerged during a dry period following planting.

The second site of action, Group 2, is the inhibition of the acetolactate synthase (ALS) enzyme, which results in the inability of weeds to produce three essential branch-chain amino acids. Lack of amino acids prevents the production of the plant proteins required for normal growth and development, which ultimately results in weed death.

What should I tankmix with Corvus?

Atrazine is a preferred tankmix partner with Corvus, as the two herbicides work together to enhance weed control beyond what the two components offer individually. Corvus is an excellent tankmix partner for numerous herbicides, including 2,4-D, Autumn™ Super and glyphosate-based herbicides. See the Corvus label for a complete listing of compatible herbicides and usage rates.

What weeds can I control with Corvus?

Corvus herbicide controls key weeds in corn, including pigweeds, waterhemp, foxtails, barnyardgrass, velvetleaf, lambsquarters and Palmer amaranth, among others. Explore the full list of weeds Corvus controls.

How do I know Corvus is working?

A clean field without any emerged weeds is the best sign that Corvus is working to control early season weeds. Weeds that do emerge may appear bleached or chlorotic (yellow), may be stunted and will eventually result in dead tissue and plant death. Bleached or chlorotic weed symptoms are likely to be observed after rain of one-half inch or more when weeds have emerged during a dry period following planting. Learn more about how Corvus has worked for real corn growers.

How long does residual weed control from Corvus last?

Corvus provides long lasting control for any weed management system. Through residual control and reactivation, growers can have confidence Corvus will deliver, regardless of weather or the types of weeds they are targeting. The best strategy for controlling weeds includes layering residuals in a two-pass system, and Corvus will help you start and finish the season clean.

Corvus Application and Use

How should I apply Corvus?

Apply Corvus as a broadcast spray in water or liquid fertilizers. Corvus is also available to band onto the soil. Applications to corn after emergence should be made in water only. For complete application details, review the Corvus herbicide label.

When should I apply Corvus?

Corvus applications are made from pre-plant burndown through pre-emergence. If weather or time conflicts postpone applications, Corvus may be used after corn emergence through the 2-leaf collar growth stage (V2). For complete timing details, review the Corvus herbicide label.

What rate of Corvus should I use?

On most medium and fine-textured soils the recommended rate is 5.6 fl oz/A. On lighter soils with lower organic matter the recommended rate is 3.33 fl oz/A. The convenient, ultra low use rate formulation of Corvus can be applied in ounces vs. pints or quarts per acre required by other herbicides. This means growers face less shipping, storage and handling, and fewer jugs. The Corvus label provides complete rate selection details based on the characteristics of your soil.

Do I need to use adjuvants or surfactants with Corvus?

Corvus herbicide provides outstanding residual weed control without the use of adjuvants. However, Crop Oil Concentrate (COC) or Methylated Seed Oil (MSO) can enhance burndown of emerged weeds 6 inches in height or less in reduced and no-till systems prior to crop emergence. Corvus plus atrazine and crop oil is an outstanding burndown program prior to crop emergence.

Corvus Product Safety

Is Corvus safe for my crops?

The Crop Safety Innovation (CSI) Safener in Corvus contributes to its broad compatibility with popular field corn hybrids. The CSI Safener enables plants to better withstand herbicidal activity, which can lead to increased root growth and plant health. The CSI Safener is an exclusive herbicide safener from Bayer. This safener has both soil and foliar uptake, which makes the safener active in both pre- and early post-applications. The CSI Safener allows Corvus to be used on any soil with greater crop compatibility and allows application through V2 corn.

Is the safener in Corvus also active on other chemistries?

The CSI Safener imparts additional protection and reduces symptoms from certain herbicides used in a tankmix or used postemergence in the early stages of corn growth, including safening the use of any dicamba product up to V2 or amide product used before crop emergence. Recovery time from many symptoms breaking through the safener protection is reduced for the crop.

What are the crop rotation restrictions with Corvus?

Crops such as wheat and soybeans typically have not demonstrated any unusual sensitivity in the season following Corvus use. You can replant corn immediately after a Corvus application, wheat after four months and soybeans after nine months. Certain crops sensitive to the components in Corvus, such as sugar beets and others, have longer rotational intervals after use of the herbicide. Most other crops can be planted 17 months after an application of Corvus. Plant-back intervals specific to various crops are outlined in greater detail on the Corvus label.

Ask Bayer

Looking for additional information about Corvus herbicide? Contact us.

©2019 Bayer CropScience LP, 2 T.W. Alexander Drive, Research Triangle Park, NC 27709. Always read and follow label instructions. Bayer, the Bayer Cross and Corvus are trademarks of Bayer. Atrazine and Corvus are Restricted Use Pesticides. For additional product information call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at
Copyright © Bayer CropScience