FAQs

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. Corvus is a proven performer, and because of that, has quickly become the #1 pre-emergent corn herbicide.

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 (link to reactivation page once created) 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 combines the strength of two sites of action to take down weeds. The first, 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 mode of action is the inhibition of the acetolactate synthase 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.

Most of the key weeds in corn are controlled by Corvus, including foxtails, barnyardgrass, pigweeds, waterhemp, velvetleaf and lambsquarters, among others.

Typically, weeds are controlled so early that they may appear to never have emerged in the corn crop. Those 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 following rain of one-half inch or more when weeds have emerged during a dry period following planting.

The Crop Safety Innovation (CSI) Safener in Corvus contributes to its broad compatibility with popular field corn hybrids. CSI 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. CSI allows Corvus to be used on any soil with greater crop compatibility and allows application through V2 corn. CSI Safener changes the ability of the plant to better withstand herbicidal activity, which can lead to increased root growth and plant health.

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.

Corvus can provide weed control well beyond canopy closure at full labeled rates, effectively controlling target weeds all season long.

On most medium and fine-textured soils the rate is 5.6 fl oz/A. On lighter soils with lower organic matter the 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 soil characteristics.

Corvus is applied 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. 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).

Corvus does not need adjuvants to provide outstanding residual weed control. 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.

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, AutumnTM Super, Liberty® and glyphosate-based herbicides. See the Corvus label for a complete listing of compatible herbicides and usage rates.

Corn can be replanted immediately after application. Wheat can be planted four months after a Corvus application, and soybeans after nine months. Most other crops can be planted 17 months following an application of Corvus.

Crops such as wheat and soybeans typically have not demonstrated any unusual sensitivity in the season following Corvus use. Certain crops sensitive to the components in Corvus, such as sugar beets and others, have longer rotational intervals after use of the herbicide. Plant-back intervals specific to various crops are outlined in greater detail on the Corvus label.