Sweet Corn Germination Issues

Sweet Corn Germination Issues - Solution Guide

Causes and Solutions for Inconsistent Seed Emergence

Spotty or inconsistent seed emergence is not normal or desirable. In most instances, these issues can be avoided. Knowing what to watch out for and how to diagnose what happened may require some digging, figuratively and literally. Digging up and examining the un-germinated seeds can help the grower figure out what went wrong by analyzing the kernels.

It is often the grower's natural reaction to blame the seed itself, however, if you have purchased and planted fresh new seed, that means any inconsistent germination is not due to the seed. We know this because all our seeds are thoroughly and rigorously tested to meet or exceed germination standards. Therefore, inconsistent germination issues will relate to cultural or environmental factors. Since so many different field condition factors exist and they tend to be the most common causes of seed germination issues. That is where to begin your analysis.

Below is a list of some of the most common reasons inconsistent or spotty emergence happens, along with some suggested solutions for how to avoid these germination issues.

Uneven or Sporadic Emergence

Causes: Studies have shown that this occurs due to 3 main reasons.

  1. Uneven soil moisture.
  2. Pockets of variable soil temperature.
  3. Both in combination.


  • Ensure organic amendments are well blended. Areas of darker soils due to amendments or moisture will naturally absorb more sunlight causing them to be inherently warmer which speeds potential seed germination in those spots compared to lighter-colored soil.
  • Seeds in depressions from equipment, footprints, or other reasons naturally catch more water which increases the speed of germination in soil depressions.
  • Ensure proper seed-to-soil contact. Avoid clumpy, cloddy soils by doing adequate shallow cultivation.
  • Periodic light rains can lead to what's called "surface cementing". Not all rain events have positive effects, be aware of what's happening in the field or garden. Use hand or mechanical cultivation if adverse soil conditions do occur. Soil crusting can negatively influence corn seed germination.

Brown, Flaking Seed, or Dissolved Seed Coat

Causes: Brown or sloughing seed tissue can be caused by many factors including high soil moisture content, heavy soil composition, or fungal infection.


  • Often due to cold, wet soils, so delay planting until soil temps have risen to a safe level.
  • Browning or flaking seed coats can occur due to soils that were wet, then becoming too dry. Keep soils consistently and properly moist.
  • Use fungicide-treated seeds to prevent attack from potential soil-borne pathogens.
  • Avoid soil surface crusting issues which can lead to inadequate soil moisture.

White/Pink Mold with Visible Hyphae on Seed or Seedling Roots

Causes: These symptoms typically relate to soil-borne fungal attacks. (Hyphae are threadlike fungal fibers)


  • Purchase and plant fungicide-treated & protected seeds.
  • Keep soils properly moist, not too wet.
  • Amend soils to ensure proper drainage.
  • Avoid planting in low-lying areas where water can pool.
  • Always plant seeds in soils with the proper temperature for the variety being planted.

Brown, Discolored Radicle (Root) or Yellow to Brown Emerging Shoots

Causes: These types of discoloration indicate fungal issues.

Solutions: Same as described above.

Abnormal Seedling Growth (Unfurling Underground or Deformed Seedlings)

Causes: Many potential causes, including soil compaction, soil surface crusting, cloddy/clumpy soils, dry soils, cool & wet conditions, planting depth, residual herbicide exposure, or combinations of any of these factors.


  • Avoid crusted soils, clumpy soils, overly dry soils, or combinations of all these.
  • Utilize proper seed depth for the variety being planted.
  • Wait for soils to properly warm and hope for optimal weather conditions.
  • Avoid herbicide exposures. (Issue is more prevalent for commercial or large-scale farmers, but all growers can heed the same warning)

No Seeds Exist After Sowing

Causes: Predation is the most common cause, but severe rot can also occur in overly wet soils.


  • Birds and rodents should be prevented where possible.
  • If this occurs, investigate as if it were a crime scene, looking for evidence of footprints, digging, tunneling, or any residual seed debris or chewed seed fragments.
  • Utilize fencing, or hardware cloth, appropriate repellents, or scare tactics for the responsible critter.
  • Promote raptor-attractive habitats. Install high pole perches for hawks & owls.

Moisture-Swollen Seeds with Little to No Germination

Causes: Inadequate seed-to-soil contact, seed planted too deep, soil temperature too low, or combinations of these.


  • Concentrate on soil cultivation techniques to promote more friable soils.
  • Avoid cloddy & clumpy soils by adding more peat moss or appropriate organic matter.
  • If you question whether the soil is crumbly enough, cultivate again.
  • Use shallow cultivation to avoid bringing copious numbers of latent weed seeds to the surface.
  • Wait for soils to sufficiently warm before planting.
  • Choose varieties with good cold soil emergence.

Seeds Have Holes or Appear Hollowed Out

Causes: These issues relate to insect damage, usually by wireworms or seed maggots.


  • Seed maggots can feed on and damage emerging seedlings.
  • Wireworms can burrow into immature roots of newly emerging corn seedlings.
  • Avoid these pests by delaying planting until soils are warm enough.
  • Avoid overly wet soil conditions.
  • Corn plantings that follow grain plantings are more susceptible to wireworms.
  • If either of these pests is suspected, contact your local agricultural extension agent for proper identification and recommended best management strategies.