Consistently scouting your corn fields early in the season is key to effective field management during one of the crop’s most vulnerable growth stages. Corn is a poor competitor in its early vegetative phases, so regularly checking your fields after planting allows you to catch and address issues early— giving your crop the best chance to reach its full yield potential.
When is the critical weed free period?
Maintaining a clean field both before and after planting is always recommended, but the most critical period for minimizing competition in corn is between the V3 and V6 growth stages. By the V3 stage—when the third collared leaf is visible—the seed’s energy reserves have been fully depleted, and the plant relies entirely on nutrient uptake through the seminal and nodal root systems. (Remember: for every collared leaf you will have two nodal roots - Ie. V3 stage only has 6 of your “money making” roots). Heavy weed concentrations throughout the field can restrict nutrient and moisture availability.
Depending on soil and atmospheric temperatures, the length of time to reach V6 can vary drastically. V6 indicates the beginning of the first rapid vegetative growth stage and canopy closure begins, allowing the crop to outcompete newly emerging weeds of sunlight.
New herbicides that provide residual coverage such as Zidua and the Laudis + Pardner duo can provide effective weed control and offer a one pass in crop option, depending on field conditions. Although these herbicides offer strong protection, scouting your field post application is still strongly recommended to ensure proper control.
Besides weed control, what else should I look for in my field?
Calculating plant stands is a simple and effective way to evaluate planter performance. Depending on your row spacing you will need to measure different lengths to get an accurate plant stand count.
While conducting population counts across the field, WATCH for skips (gaps in the row) and doubles (multiple plants emerging too close together), as these may indicate issues such as heavy residue (trash) or variable soil conditions. Observing spring emergence and early vigour is also important; strong early-season vigor helps seedlings better tolerate environmental stresses like cool temperatures and insect pressure.
To assess emergence quality, focus on plant uniformity. Ideally, all seedlings should emerge within 24 to 48 hours of the first plant breaking the soil surface, as uniform emergence sets the stage for even growth and optimal yield potential.
When digging up seedlings to evaluate stand establishment, take note of planting depth and root development (nodal and seminal root system). Seminal roots develop from the seed and support the plant in its earliest growth stages, while nodal roots, which form at the crown, become the primary source of water and nutrient uptake as the plant develops.
Healthy nodal roots are critical for stand longevity and yield potential. Poor root development can be a sign of compaction, sidewall smearing, or cold, wet soils at planting. Identifying these issues early allows for better management decisions in both the current season and future planting strategies.
What pests could be present in my field, and how can I identify them?
WIREWORMS
Wireworms are the larval stage of the click beetle and can be one of the most yield limiting early season pests, especially in the western provinces. When taking plant stand counts, it is important to notice any bare or thin patches of emerging seedlings. If wireworms are present, you will find them feeding on the imbibed seeds or newly formed roots or coleoptile. Emerged plants will show yellowing and sometimes wilted.
Their bodies are typically a reddish orange color with a dark head. Since they are not a true worm, their bodies are hard and can vary in length. Seed treatments, promoting quick, vigorous crop growth, and breaking up the rotation to limit back-to-back cereal or corn years can yield positive results when fighting with wireworms.
CUTWORMS
Cutworms are another pest species of insect that have been popping up across the western prairies. The western prairies hosts several species: Army, Red-backed, Glassy, Dingy, Darkside, and Black cutworms. Identification is crucial for understanding what control options you have.
Army Cutworm:
Larvae begin to feed in April on emerging crops and continue feeding until they begin to pupate in late May to early June. The adult moths may be noticed in late June, before undergoing summer hibernation under field trash and buildings, then become active again during their egg laying period in August and October. Adult Larvae are hairless, with a mottled body, light brown head with dark spots, and a whitish strip along the back.
RED-BACKED CUTWORM
Redbacked cutworm eggs usually hatch once the soil begins to increase in temperature in April, and begin feeding for six to eight weeks, with the most noticeable damage in June. Younger larvae damage can be seen as notches or holes cut into emerging plants, and once they get larger stem feeding occurs and is also patchy throughout the field. Identified by a characteristic brown to red stripe going down their back, separated by a lighter dark strip in the middle and two more prominent, darker browns stripes on each side.
GLASSY CUTWORM
One of the easier species to identify, the Glassy cutworm has a semi-translucent body with a dark brown to red head. These cutworms feed underground on roots and new vegetive growth (ie. Coleoptile). These cutworms can be more difficult to control as they primarily feed underground, rarely coming to the surface. Plants remain upright but are dead within the rows.
DINGY CUTWORM
Dingy Cutworms can also be easily identified by the characteristic light “V” Shape running down their back. They are light grey in color and have four black spots on each segment of their bodies. These cutworms are above-ground feeders, meaning they can climb and mainly feed on the leaves of emerging corn plants (rarely directly on stems). Female moths lay eggs in heavily weeded areas during the fall so post harvest weed control can be an effective tool to lowering populations in the coming year.
DARK SIDED CUTWORM
Dark-sided cutworms can be found wherever there are red-backed cutworms, as these populations are usually mixed. Slightly larger than the red-backed, darksided cutworms are gray in color and have a prominent white strip along each side, slightly above the legs.
BLACK CUTWORM
Black cutworms primarily feed on corn as opposed to other crops, with the most damage occurring in their first larval generation (early May – mid/late June). Typically severing the plant from the roots near the base near the soil. In early emerged corn (stages V3 to V4) larvae may burrow into plants from underground and feed on the whorl. Top half of their body is uniform in color ranging from dark grey to black.
Cutworms are general feeders, when disturbed make a distinct “C” shape. As the plant emerges, you may see two or more pinholes through the leaves, indicating burrowing through the leaves as they were still wrapped in the whorl. Once the corn is taller, most cutworm species will eat through the stocks, knocking over the plant, almost as if it were cut in half.
Most insecticide seed treatments such as Fortenza Complete found on PRIDE Seeds products can help limit damage given by both wireworms and Cutworm species. If economic thresholds are reached, pyrethroid insecticides such as Silencer are a strong option. Spraying in late afternoon to early evening offers the best coverage, as they are nocturnal feeders. Species like the Glassy cutworm that stay underground can be more difficult to control.
European Corn Borer (ECB)
ECB activity is more prominent later in the year, however feeding can occur in mid June when the corn is around V6. Larval feeding causes pinhole damage in the leaves as they unfold, much like the cutworm, sometimes there may be a “shotgun” pattern if multiple larvae are present. These pests typically target the newest growth first, which can be problematic at tassel and pollination (VT stage).
Control mainly relies on Bt corn hybrids. However, it is still crucial to monitor feeding, as Bt resistant populations of ECB have been observed as far west as Manitoba. (For more information on European Corn Borer resistant populations, visit https://cornpest.ca/corn-pests/european-corn-borer/ )
Floate, K.D. 2017. Cutworm pests on the Canadian Prairies: Identification and management field guide. Agriculture and Agri-Food Canada, Lethbridge, Alberta.
.png?upscale=true&width=1116&upscale=true&name=Zone%2064%20Your%20dedicated%20PRIDE%20Seeds%20Team%20(1).png)