Management of Herbicide-ResistantCorn Volunteers in Corn and Soybean

Mandeep Singh, Graduate Research Assistant, University of Nebraska–Lincoln

Amit J. Jhala, Professor/Nebraska Extension Weed Management Specialist

Fig. 1. (a) Cornfield infested with corn volunteers in a field near Clay Center, Nebraska (b) A clump of corn, which is more competitive than an individual volunteer corn plant.

Fig 2. (a and b) Dropped or lost corn kernels from the combine. These kernels overwinter and germinate in the spring as volunteer corn and compete with crops grown in rotation.


Volunteer corn refers to corn that grows from kernels or ears that were not harvested or were lost from the combine during the previous season (Figure 1). Often, not all of the corn kernels and ears get harvested during the season and may fall on to the ground due to mechanical harvest problems, insect damage, or natural events such as late-season windstorms. Despite advancements in mechanical harvesting, some level of harvest loss still occurs.


Provide recommendations for management of corn volunteers in corn or soybean grown in rotation.

Harvest Loss in Corn

A recent University of Nebraska−Lincoln (UNL) study that included post-harvest sampling of corn harvest loss from growers’ fields that yielded between 128 and 290 bushels/acre revealed that about 2 to 3 bu/ac of corn kernels were lost in south-central Nebraska in 2020 and 2021 (Stephens et al., 2023; Figure 2). These kernels can overwinter and emerge as corn volunteers the following season. Alternatively, in some cases, corn needs to be replanted because of a failed crop stand due to low emergence caused by cold and wet weather, poor water drainage, drought, or hailstorms during the early crop season (Figure 3). In such cases, plants remaining from a failed/poor corn stand serve as corn volunteers, which can be problematic in corn-based cropping systems in Nebraska and other Midwestern states.

Fig. 3 (a and b). Cornfields damaged by a hailstorm in early June 2022 in south central Nebraska, with replanting required in many fields (b).

Volunteer Corn: A Problematic Weed

Volunteer corn not only attracts corn rootworms, but is a very competitive weed with the next crop grown in rotation. This, in turn, can cause significant yield losses. Yield loss from volunteer corn infestation depends on the density, clump size, and crop grown in rotation. However, volunteer corn clumps are usually more aggressive than individual plants irrespective of crop type (Table 1). Research studies by UNL found that if 3,500 plants/ac of volunteer corn populations are left uncontrolled, they can cause a 2% yield loss in corn and a 10% yield loss in soybean. If this density is doubled to 7,000 plants/ac, yield loss can increase to 5% in corn and 27% in soybean (Rees and Jhala, 2018). Therefore, it is very important to control volunteer corn to prevent yield reduction.

Factors Affecting Germination of Volunteer Corn

Volunteer corn seeds from the previous season start germinating when the weather begins warming in the spring. A UNL study conducted in 2012–13 found that volunteer corn can germinate optimally well (84–97%) in a wide range of day/night temperature; 59/50 to 108.5/86°F (Chahal, 2014). The optimum pH for germination was found to be slightly acidic at 5–6 pH, resulting in 87–88% germination. The germination decreased with more acidic (47–68% at 3–4 pH), neutral (78% at 7 pH), or alkaline (62–74% at 8–9 pH) pH levels compared with the optimal. Moreover, volunteer corn seeds were found to be non-photoblastic, meaning that they will germinate regardless of whether they are exposed to light (Chahal, 2014). This indicates that shading due to crop canopy or residue will have little impact on volunteer corn germination.


Chemical Control

The herbicide options for controlling herbicide-resistant corn volunteers depend on the specific herbicide-resistant trait(s) that they possess. Additionally, the choice of herbicide(s) depends on the type of crop that the volunteer corn has infested (Table 2). Soybean has generally more in-season herbicide options, because of the selectivity of soybean to graminicides such as quizalofop (e.g., Assure® II), fluazifop (e.g., Fusilade® DX), fluazifop + fenoxaprop (e.g., Fusion®), sethoxydim (e.g., Poast®), and clethodim (e.g., Select Max®). Similarly, volunteer corn with no herbicide-resistant traits (i.e., conventional corn) generally has more herbicide options available to control it. Typically, non-selective herbicides such as glyphosate (e.g., Roundup®) and glufosinate (e.g., Liberty®) can effectively control conventional corn volunteers; however, these herbicides will not be effective for control of glyphosate/glufosinate-resistant corn volunteers if the hybrid planted was stack resistant (e.g., Roundup Ready®/LibertyLink®).

Volunteer Corn Control in Soybean

Several graminicides that can control volunteer corn irrespective of the herbicide-resistant trait (RR, LL, or RR/LL) are registered in soybean. The rate of these herbicides is volunteer corn stage-dependent, and they are often applied with adjuvants (Table 2).

Table 1: Yield loss reported due to volunteer corn infestation in corn and soybean.


Volunteer corn density

Yield Loss



32,376 plants/ac


Marquardt et al., (2012b)

2,024–48,564 plants/ac


Piasecki and Rizzardi, (2019)

2,024–48,564 clumps/ac

(7 plants/clump)


Piasecki and Rizzardi, (2019)

Corn (replanting situation)

2,024–4,047, 8,094–16,188, and 16,188–32,376 plants/ac

7–20, 44–58, and 59–81%

Shauck and Smeda, (2014)

8,094 plants/ac


Terry et al., (2012)

12,141–32,376 plants/ac

Approximately 882 lbs/ac

Steckel et al., (2009)


1,214–2,024 plants/ac


Alms et al., (2016); Marquardt et al., (2012a)

3,500–7,000 plants/ac


Wilson et al., (2010)

2,024–64,752 plants/ac


Marquardt et al., (2012a)

One clump/94 inches row length at 1,616–2,152 clumps/ac


Andersen et al., (1982)

1–10 plants/clump at 2,152 clumps/ac


Beckett and Stoller, (1988)

Table 2: Herbicide options for controlling volunteer corn in corn and soybean.

Herbicide (Trade Name)

Active ingredient

Rate (fl oz/ac)

Volunteer corn size (inches) for application


Crop for herbicide use

Traits of volunteer corn that can be suppressed/controlled**

Non-selective herbicides





AMS 1.5–3 lb/ac

Corn and Soybean



Roundup PowerMAX®




AMS 8–17 lb/100 gal

Corn and Soybean (RR, RR/LL)



Assure II




NIS 0.25% v/v or COC 1% v/v***

Corn (Enlist® corn only) and Soybean






Fusilade DX




COC 0.25% v/v






Fluazifop + Fenoxaprop



COC 0.25% v/v





NIS 0.25% v/v or COC 0.5% v/v





AMS 2.5 lb/ac



Select Max




AMS 8–17 lb/100 gal







*AMS, ammonium sulfate; COC, crop oil concentrate; NIS, non-ionic surfactant.

**CC, conventional corn; RR, Roundup Ready; LL, LibertyLink; RR/LL, a stacked trait with both Roundup Ready and LibertyLink; EC, Enlist corn.

***%v/v, percent volume/volume.

For Enlist corn, Assure II is labeled at rates of 5–12 fl oz/ac.

For effective and economical control, it is better to apply herbicides when volunteer corn is less than 12 inches in height; otherwise, higher rates of herbicides may be required for taller volunteer corn, which can increase herbicide cost. UNL research conducted at South Central Agricultural Laboratory near Clay Center, Nebraska found that quizalofop (Assure II), fluazifop (Fusilade DX), fluazifop + fenoxaprop (Fusion), and clethodim (Select Max) provided ≥ 93% control of 10- to 12-inch-tall glyphosate-resistant volunteer corn in LibertyLink soybean 15 days after application (DAA) (Chahal and Jhala, 2015). However, the control with sethoxydim (Poast) was lower (76%) in the same experiment.

Fig. 4. Glufosinate (Liberty) applied at 32 fl oz/ac controlled volunteer corn in LibertyLink soybean in an experiment conducted in 2013 at UNL’s South Central Agricultural Laboratory near Clay Center, Nebraska.

Herbicide Antagonism

Graminicides such as quizalofop, sethoxydim, clethodim, and others are commonly mixed with broadleaf herbicides such as dicamba and 2,4-D, especially when applied in soybean. This can often result in reduced grass control i.e. reduced control of volunteer corn in soybean due to antagonism from the broadleaf herbicides. Antagonism can be minimized or avoided by using a higher labeled rate of graminicide, or by applying graminicide ≥ 1 day before or ≥ 7 days after broadleaf herbicide application. For example, Assure II (quizalofop) is labelled at 4–8 fl oz/ac when applied alone for controlling 6–30 inches volunteer corn as compared with 8–12 fl oz/ac when tank-mixed with broadleaf herbicide to minimize/avoid potential antagonism (Anonymous, 2021).

Volunteer Corn Control in Corn

Compared to soybean, there are fewer herbicide options for volunteer corn control in a corn crop.

Fig. 5. Dead glyphosate/glufosinate-resistant (Roundup Read/Liberty Link) volunteer corn plants 14 days after application of 6 fl oz/ac Assure II in Enlist corn in a study conducted at South Central Agricultural Laboratory near Clay Center, Nebraska in 2021.

Fig. 6. Volunteer corn in a cornfield in south-central Nebraska. A windstorm the previous year resulted in lodging and loss of corn kernels.

If Enlist corn was planted the previous year, there is no selective herbicide that can control Enlist corn volunteers during the following year in continuous corn. Therefore, it is best to plant soybean the following year, and to use a cyclohexanedione (“Dim”) herbicide, such as clethodim (Select Max) or sethoxydim (Poast). Otherwise, if the grower decides to plant corn again, the only option to control Enlist corn volunteers in corn is through tillage, such as by using an inter-row cultivator.

Strategic Tillage

Strategic tillage is usually a reliable option, especially for pre-plant control of corn volunteers or failed corn stands under replant conditions. Tillage should be intense enough to uproot corn plants along with their roots to prevent re-sprouting. Tillage may increase the soil-to-seed contact of corn seeds from deeper soil layers by bringing them to the top, which can promote delayed emergence of corn volunteers. This can happen if the field is tilled before volunteer corn germination. In this case, a two-pass tillage program may be required, where the second pass occurs after volunteer corn emergence. Therefore, tillage might be a better option for organic crop growers who do not have an in-season herbicide option to control corn volunteers (Anderson, 2021). However, tillage may not be feasible for growers who have (1) adopted no-till as a long-term management practice; (2) adopted cover crops; (3) highly erodible soils; or (4) dryland fields where conserving soil water is extremely important (e.g., western Nebraska) (Anderson, 2021).

For in-season inter-row cultivation in soybean, it is preferred to cultivate around the V5–V6 growth stage of the volunteer corn. This is because the corn growing point does not emerge from the ground until the V6 stage, and any cultivation before that may lead to regrowth, and hence, may require additional cultivation, especially in the case of shallow cultivation (Knezevic, 2007)

Crop Rotation

Crop rotation is especially useful for corn-on-corn production fields with Enlist corn planted in the previous season, in cases of heavy pressure from volunteer corn populations, or when there is storm damage during the late crop season (Figure 6). Rotating to soybean or other broadleaf crops provides flexibility in using graminicides that are registered for those crops. In addition, because no selective post-emergence herbicides exist for control of Enlist corn volunteers in corn, rotating to soybean is a much more viable option.

Take-Home Messages


The trade names of the herbicides are given for information and clarity, and do not imply endorsement or exclusion of any product, nor does it warrant/guarantee the product standards. Always refer to the most current herbicide label for up-to-date information on herbicide use, application rates, precautions, and restrictions, and always read the herbicide label before use, and then carefully follow the label during mixing and application.

References Cited

Anonymous (2021) Assure® II Herbicide Label, AMVACTM, US. (accessed March 17, 2023).

Alms J, Moechnig M, Vos D, and Clay SA (2016) Yield loss and management of volunteer corn in soybean: Weed Technology, v. 30, p. 254–-262.

Andersen RN, Ford JH, and Lueschen WE (1982) Controlling volunteer corn (Zea mays) in soybeans (Glycine max) with diclofop and glyphosate: Weed Science, v. 30, p. 132–136.

Anderson M (2021) Expert tips for preplant control of volunteer corn prior to corn, Iowa State University Extension and Outreach: at (accessed February 19, 2023).

Beckett TH and Stoller EW (1988) Volunteer corn (Zea mays) interference in soybeans (Glycine max): Weed Science, v. 36, p. 159–166.

Chahal P (2014) Control of herbicide-resistant volunteer corn in herbicide-resistant soybean [Master’s thesis]: University of Nebraska–Lincoln, p. 51–55.

Chahal PS and Jhala AJ (2015) Herbicide programs for control of glyphosate-resistant volunteer corn in glufosinate-resistant soybean: Weed Technology, v. 29, p. 431–443.

Knezevic S (2007) Control of volunteer corn in soybean: CropWatch, University of Nebraska–Lincoln: at (accessed February 18, 2023).

Marquardt P, Krupke C, and Johnson WG (2012a) Competition of transgenic volunteer corn with soybean and the effect on western corn rootworm emergence: Weed Science, v. 60, p. 193–198.

Marquardt PT, Terry R, Krupke CH, and Johnson WG (2012b) Competitive effects of volunteer corn on hybrid corn growth and yield: Weed Science, v. 60, p. 537–541.

Piasecki C and Rizzardi MA (2019) Grain yield losses and economic threshold level of GR® F2 volunteer corn in cultivated F1 hybrid corn: Planta Daninha, v. 37, e019182131.

Rees J and Jhala A (2018) Impacts of volunteer corn on crop yields: CropWatch, University of Nebraska–Lincoln: at (accessed February 16, 2023).

Shauck TC and Smeda RJ (2014) Competitive effects of hybrid corn (Zea mays) on replanted corn: Weed Technology, v. 28, p. 685–693.

Steckel LE, Thompson MA, and Hayes RM (2009) Herbicide options for controlling glyphosate-tolerant corn in a corn replant situation: Weed Technology, v. 23, p. 243–246.

Stephens TP, Kumar V, Rees J, and Jhala AJ (2023) Estimating harvest loss of corn from growers’ fields in Nebraska and implications for volunteerism, in Proceedings, 2023 Weed Science Society of America/Northeastern Weed Science Society Annual Meeting: Arlington, Virginia, Weed Science Society of America, p. 8.

Striegel A, Lawrence NC, Knezevic SZ, Krumm JT, Hein G, and Jhala AJ (2020) Control of glyphosate/glufosinate-resistant volunteer corn in corn resistant to aryloxyphenoxypropionates. Weed Technology, v. 34, p. 309–317.

Terry RM, Dobbels T, Loux MM, Thomison PR, and Johnson WG (2012) Corn replant situations: Herbicide options and the effect of replanting into partial corn stands: Weed Technology, v. 26, p. 432–437.

Wilson R, Sandell L, Robert K, and Mark B (2010) Volunteer corn control, in Proceedings, Crop Production Clinics, 2010: Lincoln, Nebraska, University of Nebraska–Lincoln Extension, p. 212–215.

Zimmer M and Johnson B (2020) Control of “volunteer” corn in a corn replant situation: West Lafayette, Indiana, Purdue University Extension Pest & Crop Newsletter: at (accessed February 17, 2023).

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