Vegetative Corn Growth Stages and Scouting Tips
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Stages:
VE - V1
VE - V1: Germination and Emergence*
Once planted, corn seeds absorb water from the soil and begin to grow. VE (emergence) occurs when the coleoptile (spike) pushes through the soil surface. Corn plants can emerge within 5 days in ideal heat and moisture conditions. But in practice, due to early planting under seasonably cool conditions, at least 2 weeks are normally required from planting to emergence. With below average spring temperatures, corn seeds may be in the ground for 3 weeks or more before seedlings emerge. The growing point (stem apex) is 1 to 1.5 inches below the surface. The seminal root system is growing from the seed. The seminal roots do much of the early work, but growth slows after VE as nodal roots begin to grow.
The young plant has developed to the point that the collar is showing on the first leaf. This leaf is usually more rounded at the tip than succeeding leaves. From here each vegetative stage is determined by counting the visible collars in the sequence V1, V2, V3…VN until the tassel emerges at VT and maximum height is attained. When counting beware that some early leaves may have been lost from the bottom of the plant. At the V1 stage leaves are being initiated from a growing point below the surface of the soil as cell elongation has not yet begun. The initial seminal root system continues to grow and expand with branches and hair roots. The beginning of the nodal root system may also be visible as bumps at either 1 or 2 nodes at the lower end of the coleoptile and above the mesocotyl.
Tips*
- Longer-season hybrids generally have more yield potential than shorter-season hybrids.
- Growers should choose hybrids based on the local growing season and specific field environment.
- Cool temperatures restrict root growth and nutrient uptake.
- Banding fertilizer can help increase nutrient availability and early growth.
- Shallow planting may provide a warmer environment for seeds when planting early, but always plant at least 1.5 inches deep for normal plant development.
GDUs Required: 100
Note: GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.
| Scout for these Common Pests and Diseases | Timing* |
|---|---|
| Brown Stink Bug | VE through V4. |
| Corn Flea Beetle | During the first three weeks after VE and again in early R stages. |
| Goss's Wilt | VE through R6. Disease primarily found in Nebraska and portions of other western states. |
| Grape Colaspis | VE through V8. |
| Seedcorn Maggot | From planting to VE. |
| Slugs | VE through V4. |
| Stewart's Wilt | Disease is initiated with corn flea beetle feeding from VE to V5. |
| White Grub | From VE to V3. |
| Wireworms | From planting to V4. |
V3
V3 Stage*
At V3, the growing point is still below the surface. The stalk (stem) hasn't elongated much. Root hairs are growing from the nodal roots as seminal roots cease growing. All leaves and ear shoots the plant will ever produce form inside the stalk from V3 to about V5. A tiny tassel forms at the tip of the growing point. Above-ground plant height typically is about 8 inches.
Tips*
- Soil temperatures greatly affect the growing point.
- Cold soils may increase the time between leaf stages, increase the total number of leaves formed, delay tassel formation and reduce nutrient availability.
- Hail, wind and frost have little effect on the growing point or final grain yield.
- At this time, flooding can kill the corn plant.
- Weed control reduces competition for light, water and nutrients.
GDUs Required: 325
Note: GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.
| Scout for these Common Pests and Diseases | Timing* |
|---|---|
| Black Cutworm | Mid- to late May until corn reaches V5. |
| Brown Stink Bug | VE through V4. |
| Goss's Wilt | VE through R6. Disease primarily found in Nebraska and portions of other western states. |
| Grape Colaspis | VE through V8. |
| Slugs | VE through V4. |
| Stewart's Wilt | Disease is initiated with corn flea beetle feeding from VE to V5. |
| Wireworms | From planting to V4. |
V6
V6 Stage*
The growing point and tassel rise above the soil surface at about the V6 stage. The stalk begins to elongate. The nodal root system grows from the 3 to 4 lowest stalk nodes. Some ear shoots or tillers are visible. Tiller (or sucker) development depends on the specific hybrid, plant density, fertility and other conditions. The number of kernel rows is being determined from V7 to V8.
Tips*
- Precise fertilizer placement is less critical as roots spread.
- Watch for signs of nutrient deficiencies.
- Foliar or soil applications may help, but deficient soils are best corrected before symptoms appear.
- Sidedress nitrogen from V6 to V8 to help ensure its availability when plants need it most.
- Begin to scout for insect damage such as lodged plants (rootworms) or leaf feeding (corn borers.)
GDUs Required: 550
Note: GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.
| Scout for these Common Pests and Diseases | Timing* |
|---|---|
| Corn Rootworm | Larval feeding is most extensive in early through mid-July in most regions of the Corn Belt. |
| European Corn Borer | As the true stalk develops and European corn borer larvae increase in size, larvae can be found tunneling into the stalk. |
| Eyespot | V6 through R4. Disease primarily found in northern environments. |
| Goss's Wilt | VE through R6. Disease primarily found in Nebraska and portions of other western states. |
V9
V9 Stage*
Dissection of a V9 plant shows many ear shoots (potential ears). These develop from every above-ground node except the last 6 to 8 nodes below the tassel. Lower ear shoots grow fast at first, but only the upper 1 or 2 develop a harvestable ear. The number of kernel rows is determined by V9. The tassel begins to develop rapidly. Stalks lengthen as the internodes grow. By V10, the time between new leaf stages shortens to about every 2 to 3 days.
Tips*
- At about V10, rapid increases in nutrient and dry weight accumulation begin. This continues into the reproductive stages.
- Soil nutrient and water requirements are very high due to the increased growth rate at this stage.
GDUs Required: 730
Note: GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.
| Scout for these Common Pests and Diseases | Timing* |
|---|---|
| Corn Rootworm | Larval feeding is most extensive in early through mid-July in most regions of the Corn Belt. |
| European Corn Borer | As the true stalk develops and European corn borer larvae increase in size, larvae can be found tunneling into the stalk. |
| Eyespot | V6 through R4. Disease primarily found in northern environments. |
| Goss's Wilt | VE through R6. Disease primarily found in Nebraska and portions of other western states. |
V12
V12 Stage*
The potential of kernels per row is determined by at least V15 and maybe as early as V12. The top ear shoot is still smaller than the lower ear shoots, but many of the upper ears are close to the same size.
Tips*
- Moisture or nutrient deficiencies from V10 to V15 significantly reduce kernel numbers, ear size and grain yield.
- Earlier-maturing hybrids progress through growth stages in less time and generally produce smaller ears than later-maturing hybrids. Thus early-maturing hybrids need high plant densities for maximum yields.
GDUs Required: 910
Note: GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.
| Scout for these Common Pests and Diseases | Timing* |
|---|---|
| Corn Rootworm | Larval feeding is most extensive in early through mid-July in most regions of the Corn Belt. |
| European Corn Borer | As the true stalk develops and European corn borer larvae increase in size, larvae can be found tunneling into the stalk. |
| Eyespot | V6 through R4. Disease primarily found in northern environments. |
| Goss's Wilt | VE through R6. Disease primarily found in Nebraska and portions of other western states. |
V15
V15 Stage*
This is the start of the most crucial period for determining grain yield. Upper ear shoot development overshadows lower ear shoot development. Every 1 to 2 days, a new leaf stage occurs. Silks begin to grow from the upper ears. By V17, the tips of upper ear shoots may be visible atop the leaf sheaths. The tip of the tassel also may be visible.
Tips*
- The corn plant is most sensitive to drought stress starting two weeks before silking until two weeks after silking. Grain yields are most affected from drought during that period.
- The closer to actual silking, the more yield reduction from stresses such as nutrient deficiencies or hail.
- When fields are dry avoid applications of fungicides, pesticides and associated surfactants. (Read and follow label directions.)
- Critical period for irrigation.
GDUs Required: 1,045
Note: GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.
| Scout for these Common Pests and Diseases | Timing* |
|---|---|
| Corn Rootworm | Larval feeding is most extensive in early through mid-July in most regions of the Corn Belt. |
| European Corn Borer | As the true stalk develops and European corn borer larvae increase in size, larvae can be found tunneling into the stalk. |
| Eyespot | V6 through R4. Disease primarily found in northern environments. |
| Goss's Wilt | VE through R6. Disease primarily found in Nebraska and portions of other western states. |
V18
V18 Stage*
Silks from the basal ear ovules elongate first. Silks from the ear tip ovules follow. Brace roots (aerial nodal roots) grow from the nodes above the soil surface to help support the plant and take in water and nutrients during the reproductive stages.
Tips*
- The plant is about a week away from silking.
- Ear development is rapid.
- Stress can delay ear and ovule development more than tassel development. Such a delay would mean a lag between pollen shed and silking. Severe stress may delay silking until after pollen shed, resulting in unfertilized ovules.
- Damage (arrested ear development) has been reported from fungicide applications that included non-ionic surfactants prior to tasseling.
GDUs Required: 1,180
Note: GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.
| Scout for these Common Pests and Diseases | Timing* |
|---|---|
| Corn Rootworm | Larval feeding is most extensive in early through mid-July in most regions of the Corn Belt. |
| European Corn Borer | As the true stalk develops and European corn borer larvae increase in size, larvae can be found tunneling into the stalk. |
| Eyespot | V6 through R4. Disease primarily found in northern environments. |
| Goss's Wilt | VE through R6. Disease primarily found in Nebraska and portions of other western states. |
VT
VT Stage*
The VT stage arrives when the last branch of the tassel is completely visible. VT begins about 2 to 3 days before silk emergence. The plant is nearly at its full height. Pollen shed begins, lasting about 1 week on an individual plant basis and 1 to 2 weeks on a field basis. The interval between VT and R1 can fluctuate considerably depending on the hybrid and the environment. Drought stress lengthens this interval.
Tips*
- With the tassel and all leaves exposed, the plant is extremely vulnerable to hail from VT through silking (R1). Total removal of leaves can devastate yield potential.
- If ovules aren't fertilized they produce no kernels on the cob.
GDUs Required: 1,260
Note: GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.
| Scout for these Common Pests and Diseases | Timing* |
|---|---|
| Corn Earworm | Arrival of adult moths from southern states varies each year. Corn at VT to R1 is most attractive to egg-laying females. Scout at R1 or when a significant moth flight is captured in pheromone traps. |
| Corn Rootworm | Larval feeding is most extensive in early through mid-July in most regions of the Corn Belt. |
| European Corn Borer | As the true stalk develops and European corn borer larvae increase in size, larvae can be found tunneling into the stalk. |
| Eyespot | V6 through R4. Disease primarily found in northern environments. |
| Goss's Wilt | VE through R6. Disease primarily found in Nebraska and portions of other western states. |
| Gray Leaf Spot | VT through R4.** |
| Japanese Beetle | VT through R1, until pollination is complete. |
| Northern Leaf Blight | VT through R4.** |
| Southern Leaf Blight | VT through R4.** |
| Western Bean Cutworm | Initiate scouting based on local pheromone trap captures of adults. If trap data are unavailable, begin scouting at VT. |
*Information from Pioneer and Iowa State University Extension.
** Scout for these diseases earlier in seed production fields.