The Earfull July 13, 2026

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When Corn and Soybeans Start Making Their Own Weather

In a lot of areas, the air does not just feel hot. It feels heavy. Part of that is the weather pattern itself, but part of it is the crop. As corn and soybean canopies move large amounts of water from the soil, through the plant, and out into the air, they help create the sticky field conditions many scouts are walking into this week.

That matters because a hot, humid stretch is not only a comfort issue for people in the field. It is also a real test of how efficiently plants can keep moving water, keep tissues cool, and hold reproductive timing together as corn reaches tassel and soybeans edge deeper into flowering.

corn row

Corn is entering the key window

The main agronomic issue is not simply that highs may reach around 95-100 degrees. The bigger issue is that much of the crop is entering pollination, with some acres just beginning pollen shed and others likely several days into it. The forecast favoring above-normal temperatures across most of the country can be impacted by this growth stage. Here’s why.

Corn has one main way to manage heat: move water. When soil moisture and root function are still adequate, the plant can keep transpiring, which helps cool the canopy and supports continued silk growth and pollen movement. When that water pipeline starts to tighten, the plant shifts quickly from managing heat to conserving moisture, and that is when stress becomes more visible in the field.

This helps explain why two fields with similar calendar dates can respond very differently in the same weather pattern. Deeper soils, stronger rooting, and more even early-season development can give one field enough buffer to move through a hot week with modest impact, while lighter ground or compacted areas may begin to roll early, shorten silk growth, and raise concern about kernel set.

Humidity is an important part of this story. High humidity can reduce atmospheric demand compared with a hot, very dry wind event, but it also reflects how much water the crop is already pushing into the air. In other words, the same humidity that makes the day feel oppressive can also be a sign that the crop is working hard to cool itself.

The practical question is whether fields can keep that cooling system running through pollen shed. If plants still have access to moisture, the crop can often ride through several warm days. If moisture supply slips, especially on lighter soils or in uneven parts of fields, stress can show up first in delayed silk emergence, extended leaf rolling, and greater variability from one ear to the next.

What to watch during pollen shed

This is a good week to shift scouting from general appearance to reproductive function. A field can still look decent from the road and be less synchronized than expected once you move beyond the ends and start checking tassels, silks, and plant response through the middle of the day.

A few checks matter right now:

  • Confirm actual pollen shed timing by field instead of relying on tassel visibility alone. A field that has tasseled is not necessarily shedding uniformly yet.
  • Watch how early leaf rolling begins and how long it lasts. Brief afternoon rolling is different from leaves tightening by late morning and holding most of the day.
  • Check silk emergence across multiple management zones, especially lighter soils, compacted areas, and places that ponded earlier in the season.
  • Pay attention to warm nights. Limited nighttime recovery can leave plants starting the next day with less margin than they had before.

A useful way to describe this week’s risk is this: heat by itself is not automatically a yield loss story, but heat during pollen shed can become one quickly if it overlaps with uneven moisture supply or weak silk progression. That is why this stage deserves more than a windshield check.

soybean row

Soybeans are helping create the humidity, too

Soybeans are not at the same make-or-break stage as pollinating corn, but they are still part of the heat story. Many bean fields are building canopy, moving into flowering, and transpiring heavily, which contributes to the damp, heavy air many people are noticing around productive fields.

This does not mean soybeans are carefree under these conditions. If moisture remains available, beans can usually handle short stretches of heat better than corn and still retain strong yield potential. But warm nights, dense canopies, and prolonged humidity can raise respiration costs and increase the chance that disease risk starts to build in fields with a history of foliar pressure.

Soybeans also remind us why broad crop ratings only tell part of the story. A statewide number can look stable while individual fields differ sharply based on planting date, canopy closure, weed competition, compaction, and rainfall luck over the last few weeks.

Field reality over headline reality

Markets have been reacting to weather concerns, and forecasts continue to keep traders focused on the pollination window. That attention makes sense, but the best agronomic read this week still comes from separating field classes by actual stress response instead of by headline intensity.

References

The Earfull July 6, 2026

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As We Head into the First Full Week of July

corn row

This week’s EARFULL takes a step back from the noise and looks at what early July heat and humidity mean for pollination, how to think about good-to-excellent crop ratings, and what is worth scouting in your own fields over the next 10 to 14 days.

Early July heat

Forecasts point to a hot, humid start to July across much of the central and eastern United States. Not to overstate it, but heat index values frequently topping 100 degrees and warm nights offering limited recovery. That lines up with what many growers are seeing in the field as corn begins to show stress faster on lighter soils and more exposed ground.

From an agronomy standpoint, the key questions are timing and duration. Corn is most vulnerable when high heat overlaps the pollination window, especially when nights stay warm and soil moisture is already drying out. A brief burst of heat with decent subsoil moisture is usually a stress test. A longer stretch of heat, wind, and limited rainfall is when real concern starts building around kernel set.

A few field checks matter this week:

  • Flag fields that are within 10 days of tassel and already showing stress on lighter soils.
  • Monitor overnight lows alongside daytime highs, as warm nights reduce crop recovery.
  • Note when leaf rolling begins. Corn that rolls by mid-morning and stays there all day is signaling that the moisture profile is getting short.

The goal is not to overreact to a single hot forecast, but to identify which fields could become vulnerable if the pattern holds.

Crop condition

USDA reporting showed U.S. corn with 67 percent rated good to excellent and soybeans at 65 percent good to excellent as of late June. This reflects generally favorable conditions across much of the Midwest, helping explain why market commentary can sound calm even while individual farms are dealing with drowned-out spots, uneven stands, or short-term moisture stress.

Both views can be true at the same time. Broad ratings capture the region, but they do not highlight field-to-field variability. University and federal climate resources for Midwest agriculture also point to greater weather variability and uneven rainfall patterns as ongoing management challenges for corn and soybean systems.

That makes local field evaluation more valuable than ever. Scouting tips at this critical stage:

  • Walk beyond the end rows before judging stand and vigor.
  • Rate fields as solid, borderline, or concerning based on stand, color, root development, and soil moisture.
  • Pay close attention to areas that either ponded in June or consistently missed rainfall, because those zones may react very differently under this early July heat.

By early July, field reality usually tells more than a statewide average.

Soybeans still have runway

Soybeans have generally progressed well so far this season, and early condition ratings have stayed favorable in many key states. This has encouraged some early-season optimism, but soybeans still have a long way to go before final yield is set.

Beans can compensate better than corn if they catch moisture during flowering and pod set, but they remain sensitive to stress during reproductive development. Iowa State’s late-June regional crop update noted that soybeans were generally in the V3 to V5 range while much of the corn crop was in the V5 to V7 window, reinforcing that both crops were still moving through important vegetative stages heading into July.

A practical soybean checklist for the next two weeks includes:

  • Check growth stages in the fields carefully so you know which acres are moving into flowering under stress.
  • Prioritize weed escapes, especially where late competition can rob moisture and sunlight.
  • Watch denser canopies, where continued humidity could raise disease risk.

Strong-looking beans in late June are encouraging, but they are not a finished crop.

As the calendar turns into July, the conversation should stay centered on timing. Heat alone does not necessarily mean yield loss, and strong early ratings do not guarantee the rest of the season. Pollination, flowering, soil moisture, and field variability are the real story right now.

The best move this week is simple: scout the fields closest to tassel and first bloom, sort them by risk, and keep separating general talk from field-specific reality. This approach usually leads to better agronomy decisions than reacting to the loudest headline.

References

The Earfull June 22, 2026

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What Needs Attention Right Now

By this point in June, the crop has usually settled enough that the overall story starts to look fairly positive from the road. A lot of corn has good color. A lot of soybeans are moving along. Most fields are far enough along that the season feels established rather than uncertain. This is the good news.

The other side of the story is that it’s also the time when averages become less useful. As a whole, the field can still look decent and yet have enough stress pockets, stand variation, root issues, or weed escapes to quietly trim yield potential before anyone fully realizes it. This is why the better agronomy conversations right now are shifting away from broad planting progress and toward a much more practical question: where is the crop beginning to separate inside the field?

Nationally, the crop remains in a generally workable position. USDA condition ratings suggest both corn and soybeans are still holding together reasonably well as we move deeper into June. That is encouraging. But those ratings do not tell the full local story, especially in areas where compaction, variable rainfall, sidewall effects, crusting, uneven emergence, or herbicide timing are now becoming more apparent.

Corn

corn plant

Corn is moving fast enough now that some early-season issues can get masked for a while. A field may have a strong green color from the road and still contain areas where root development is weaker than expected, growth is uneven, or nutrient uptake has been limited by early conditions. In many cases, these are the same places that tend to show up every year: sidehills, worked ends, low spots, compacted zones, or fields where planting conditions were just a little less forgiving than the grower thought at the time.

This is a good week to look beyond color alone. Pale or uneven corn does not always mean the same thing. Sometimes, it is a temporary response to cooler soils or saturated conditions that the crop will largely outgrow. Other times, it is a sign that the root system never fully established itself as it needed to. Or, it could be that nitrogen and sulfur uptake are lagging because the plant has not had ideal conditions to keep pace with rapid vegetative growth.

The main point is to identify whether the pattern is random or repeatable. If the issue lines up with wheel tracks, drainage patterns, soil changes, or known parts of the field, there is usually something useful to learn from it. Those are the fields worth digging. Pull some plants. Check root development. Look for sidewall restriction, shallow roots, crown health, and whether nodal roots are doing what they should at this stage.

Soybeans

Soybeans deserve the same kind of attention right now, even though they can be easier to overlook. A soybean field often has a way of appearing acceptable until you walk farther into it. Once you walk into it, things may begin to stand out more than they did from the road: thinner areas, uneven growth, crusted pockets, ponded spots, or delayed sections.

This is especially true in fields that were planted in less-than-ideal conditions or in those that had an uneven start. In June, soybeans can still compensate for a lot. They compensate best when the stand is more uniform than it first appears and when stress remains relatively limited from this point forward. Where populations have thinned or roots are restricted, the field may still be fine overall, but it deserves a closer look before writing it off as “good enough.”

This is also the point where weed pressure starts becoming more visible. Residual programs that looked solid earlier can begin to lose their edge, and escapes start showing up in the fields that were a little delayed, a little uneven, or simply stretched on timing. That does not mean every field has a major weed problem. It does mean this is the week to identify the acres where weeds are starting to win small battles before they become larger ones.

The Next 7 to 10 Days

For the next week or so, the best use of scouting time is probably not in the cleanest or most even fields. It is in places that feel just a little off. That could be corn that is not quite as uniform as the neighboring field. It could be soybeans that seem a little thinner than expected. It could be fields where the first pass looked good, but you are starting to wonder if weeds are slipping through.

In corn, keep the focus on stand consistency, root strength, and whether stress follows a clear pattern. In soybeans, count viable plants in weaker spots, look at root development, and ensure emerging weed escapes are identified while practical options are still available. This is also a good time to make notes that will matter later. Many of the best decisions in July and August come from observations made now.

There is still a lot of yield potential ahead for this crop. Most acres do not need a dramatic reaction. They need a careful eye, timely walking, and a willingness to investigate the areas that are easy to dismiss when the rest of the field looks fine. This is usually where the most useful answers are found at this time of year.

References

The Earfull June 15, 2026

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row of corn seedlings

Heat and Wind: Regional Product Impacts

Corn is moving fast across the Renk sales area, and that fast growth is exposing two different structural issues in the same season: floppy corn and early greensnap, also called brittle snap. They can show up after the same weather pattern, and they can both be blamed on wind, but they are not the same problem. Floppy corn is mainly an anchorage issue tied to nodal root development, while early greensnap is a stalk failure issue tied to rapid growth and storm timing.

That distinction matters right now because some growers are seeing fields lean or flop after wind, while others are seeing plants actually break off in an earlier-than-normal snap window. This year’s crop has advanced quickly enough that both problems can be present at once, sometimes even within the same general geography.

Floppy Corn

Floppy corn, often called rootless corn syndrome, develops when nodal roots fail to anchor the plant well enough as it transitions out of dependence on seminal roots. The field symptom is familiar: corn may look green, healthy, and aggressive from the road, but after a windy day it leans badly or lays over because the crown root system did not establish enough hold in the soil.

This issue usually traces back to conditions around planting and early root establishment. Shallow planting, loose or fluffy seedbeds, rapid drying near the soil surface, crusting, erosion around the row, and compaction that interferes with nodal root development can all leave the plant under-anchored at the exact time it starts adding height quickly.

This is why floppy corn can show up even in fields that otherwise seem to have excellent color and above-average early vigor. In fact, the fast growth itself can make the problem look worse because a taller, rapidly expanding plant puts more leverage on a root system that is not yet fully secured.

In some areas, this season has created a good setup for floppy corn because growth has moved quickly while surface moisture has remained variable. Wisconsin Extension noted that rainfall patterns have been uneven. Stop-and-go moisture can leave the upper root zone unfavorable for nodal root establishment, even when the crop still looks good overall. On plants where the upper inch or two dried down quickly, nodal roots may have struggled to become fully grown and anchor before wind events tested them.

It is also important to remember that floppy corn is not always uniform across a whole field. It often shows up in lighter soils, sidehills, worked ends, compacted zones, or places where the crown area is effectively positioned too close to the soil surface. That patchiness is one reason the problem can be underestimated until a storm, high winds, or even a trip across the field makes the weak-rooted plants obvious.

Product differences may also influence how often floppy symptoms show up and how well plants recover after stress. Environment and planting conditions are still the main drivers, but field experience supports the idea that not every product responds the same way when root establishment is challenged. The encouraging side of floppy corn is that some plants can recover if they receive timely rainfall and are able to push a stronger nodal root system after the stress event.

rows of corn seedlings

Early Greensnap

Alongside floppy corn, some growers are reporting early greensnap after major wind events. This is different from leaning or rootless corn because the stalk is actually broken, usually at or near a node, rather than simply tipping because roots failed to anchor the plant.

What makes this notable in 2026 is the concern is coming from an earlier window than typically thought about by many growers. Agronomy references describe an early greensnap risk period around V5 to V8. This lines up with reports from fields that were around V4 to V6 and entering a rapid structural change when storms came through. Most years, greensnap gets the attention later, from V8 toward tassel, because that is when corn is visibly tall and rapidly elongating.

Not every product responds the same way under the same weather event. Hybrid differences in greensnap susceptibility are real, which is why some fields, products, or placement zones may show more breakage than neighboring acres exposed to a similar storm.

Another part of the discussion is whether herbicide programs may have contributed to some of the early snap reports. The answer is yes. They can be part of the risk picture, especially where growth regulator herbicides were applied during the V5 to V8 period.

This is especially true in a year when crop growth has been so rapid. A field moving quickly through V5 to V8 can already be structurally tender, so any additional stress or hormonal affect from a growth regulator program may help explain why some acres were more brittle than expected when the storm arrived.

Takeaway

The main takeaway this week is that rapid early growth has exposed weak points in more than one way. Floppy corn remains a major part of the story because many plants are being tested before nodal root systems are fully secure, while early brittle snap is surfacing because storms are colliding with corn just as it enters a fragile growth window.

This is why the current season feels different: uneven surface moisture, fast development, high wind events, hybrid differences, and possibly growth regulator timing are all layering together. The best agronomy conversations right now are the ones that separate floppy corn from true stalk snap. Then, work backward through field conditions, product response, and management timing to understand each field’s reaction.

References

The Earfull May 18, 2026

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Early-Season Stands Set the Tone

Planting is nearing the finish line across much of the Upper Midwest, let’s look into stand evaluation. In both corn and soybeans, this is the point where visual impressions need to give way to counts, uniformity notes, and realistic replant economics. This issue focuses on three practical questions: how far scouting counts should run by row width, what stand is actually there, and when is a thin or uneven stand still worth keeping.

Row width

Distance to count

15-inch

34 ft 10 in

20-inch

26 ft 2 in

22-inch

23 ft 9 in

30-inch

17 ft 5 in

Stand count chart: Use the 1/1000-acre method for fast, repeatable stand counts. Measure the row length below, count only viable plants, and multiply the count by 1,000 to estimate plants per acre. 

Stand count scouting technique

  • Do counts from four to six representative spots in a field, plus separate notes from obvious problem areas.
  • Count only live plants with a realistic chance to continue developing; dead or clearly noncompetitive plants should not be included.
  • Record skips, doubles, delayed plants, crusting, ponding, or sidewall issues while counting, because stand quality matters along with final population.
  • Average the counts from representative areas and multiply by 1,000 to estimate the final stand per acre.
  • Example calculation: In a 30-inch row, a scout counts 29 live corn plants in 17 feet 5 inches. That equals about 29,000 plants per acre. Four counts of 28, 30, 31, and 29 plants would average 29.5, or about 29,500 plants per acre.

Corn, the goal is simple: get every plant out of the ground at the same time and keep early stress from turning into uneven development. Uniform emergence matters because later plants act more like weeds than full contributors, and research summaries show meaningful yield loss when a portion of the stand lags by one to two leaf stages.

Corn is less forgiving than soybeans when emergence is uneven, so both stand and plant-to-plant uniformity should drive the decision. Replant tables are built around the trade-off between reduced current stand and delayed replant yield potential.

Final stand

Before May 10

May 10–20

After May 20

24,000+

Keep

Keep

Keep

20,000–23,999

Keep if uniform

Consider economics

Usually keep

16,000–19,999

Compare yield vs. delay

Borderline

Often keep

Below 16,000

Strong replant case

Case-by-case

Late replant risk

The matrix is built on a target planting rate of 32,500 so if you have lower planting targets, this matrix would need to be lower based on your planting rate.

Corn scouting reminders

  • Uneven emergence can cost yield even when total population looks acceptable.
  • Dig plants in uneven areas to check for sidewall compaction, crusting, seed furrow issues, or early root restriction.
  • Replant decisions should be based on surviving stand, uniformity, and realistic replant date, not appearance from the road.

Soybean stand review should be top of mind this week because many early-planted fields are now emerging unevenly after cool conditions, surface crusting, and scattered ponding events. The first question is not whether the stand is perfect, but whether it is uniform, healthy, and above the practical threshold where replanting usually fails to return enough yield to pay for itself. Use stand counts from several representative areas and only count live plants that are likely to continue developing. The same 1/1000-acre method works for soybeans in the chart from the earlier section, but acceptable final stands are often lower because soybeans compensate through branching.

Soybean replant decisions should center on live stand, spacing, and date rather than chasing a perfect-looking field. Early-planted soybean stands can often be left at lower populations than most growers expect, particularly when plants are healthy and gaps are limited.

Final stand

Before May 15

May 15–31

June

100,000+

Keep

Keep

Keep

75,000–99,999

Keep if uniform

Keep

Keep

50,000–74,999

Consider gaps and vigor

Usually keep

Keep

Below 50,000

Replant or fill-in case

Borderline economics

Late replant often loses

Soybean scouting reminders

  • Desired stands may be near 100,000 plants per acre, but uniform stands near 70,000 to 75,000 can still retain most yield potential.
  • Early-planted fields below 75,000 plants per acre deserve closer review, while late-May and June fields often have lower replant thresholds around 50,000 to 60,000 plants per acre.
  • Large dead gaps, seedling disease, ponding, and uneven emergence matter more than cosmetic thinness alone.

References

The Earfull May 11, 2026

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GDUs

Planting progress is rapidly moving forward even with the cold and windy conditions. This week, let’s focus on growing degree unit (GDU) tracking and early nitrogen planning. Corn development does not move by calendar date alone; it moves by heat accumulation, so the best early-season management starts with matching field observations to GDU totals and then using that information to stay ahead of nutrient demand.

The formula for GDUs: take the daily high plus the daily low, divide by two, then subtract 50. For corn, the high is capped at 86°F and the low is floored at 50°F because growth does not keep accelerating above 86°F and development slows sharply below 50°F. A simple example helps. If the high is 64°F and the low is 50°F, the average is 57. This would be a 7 GDUs day. If the high is 92°F and the low is 46°F, the adjusted values become 86 and 50, so the crop gains 18 GDUs rather than 19. That keeps the number tied more closely to how corn develops.

Emergence generally occurs after about 100 to 120 GDUs, and from emergence through about V10, leaf collars typically appear at roughly one new stage every 82 to 85 GDUs. That means GDU tracking can be turned into a practical field forecast: once a field is planted, growers can estimate when it should emerge, when it should reach key vegetative stages, and when management windows such as post herbicide or sidedress nitrogen are approaching.

knife demonstrating soil depth for seed planting

This matters most in uneven springs. Cool nights, dry topsoil, crusting, and variable residue can make neighboring fields look different even when they were planted within a day or two of each other. In those situations, GDU totals help separate true agronomic delay from visual noise. A field that has not yet accumulated enough heat for the next stage may simply be behind thermally, not necessarily in trouble.

A simple way to use GDU tracking this month is to pair three checks together. First, record planting date by field. Second, track cumulative GDUs from planting. Third, confirm actual stage by leaf collar, not plant height. Height can change fast with weather, but collar stage is the more reliable way to line up crop development with input timing. In practical terms, if a field has accumulated around 120 GDUs after planting, emergence should be close. If it has moved well beyond that and stand is still uneven, that is the time to dig, inspect seedling health, and look for moisture, crusting, insect, or disease issues rather than guessing from the road.

The next key point is that early vegetative stages set up later opportunity. Corn progresses rapidly once conditions turn favorable. Under good conditions, a young plant can unfurl a new leaf every 3 to 4 days, and later in vegetative growth leaves can appear every 2 to 3 days. That pace is why weekly scouting needs to become more disciplined in May. Fields can move from emergence to the start of rapid uptake windows in a surprisingly short stretch, especially when temperatures run slightly above average or maybe stretch out with colder than average conditions like we are seeing this year.

Tracking GDUs also improves communication across farms and teams. Saying a field is “just starting” is vague. Saying it was planted April 28, has accumulated roughly 190 GDUs, and is at V1 to V2 gives a clearer read on what should happen next and whether the crop is on pace. That kind of discipline helps prioritize scouting, herbicide timing, replant discussions, and fertility plans.

Why Sidedress Nitrogen May Deserve a Closer Look in 2026

With fertilizer costs under pressure again in 2026, sidedress nitrogen deserves renewed attention to protect both nitrogen efficiency and crop response.

In years like this, the question is not only how much nitrogen to apply, but when to put the bulk of it at risk. Wisconsin guidance has long shown that interest in sidedress nitrogen rises when fertilizer costs are high because delayed application can improve nitrogen effectiveness and help avoid some losses before the crop needs the full supply. That idea lines up well with how corn grows. Corn begins rapid growth and nitrogen uptake around the V5 to V6 stage, making the V4 to V6 period a practical target for many sidedress operations. University of Minnesota guidance similarly points to V4 to V8 as the best timing window, with sidedress no later than about V8 to V9 when a modest starter or preplant nitrogen program has already carried the crop.

The value of sidedressing is straightforward. Nitrogen placed months ahead of peak use can be vulnerable to loss from wet soils, denitrification, leaching, or surface volatilization, depending on source and conditions. By moving a meaningful share of total nitrogen closer to the crop’s demand curve, growers may reduce exposure to those loss pathways and keep more applied nitrogen available when the plant is entering rapid uptake.

This strategy is not a fit for every acre or every operation. It requires labor, equipment, timeliness, and a willingness to scout. But it can make sense where springs are wet, where soils are more prone to losses, where planting windows compress fertilizer decisions, or where a grower wants flexibility to adjust rates after seeing stand establishment and yield potential.

Source and placement still matter. Urea and UAN (28% or 32%) are common sidedress sources, but surface-applied materials can be exposed to volatilization, especially when hot and dry conditions follow application without rainfall. Where UAN is knifed in and the slot closes, a urease inhibitor is often less necessary; where urea or UAN remains on the surface, rainfall timing and inhibitor use become more important considerations. That means sidedress is not automatically efficient just because it is later. It works best when timing, source, placement, and weather are all considered together.

The 2026 takeaway is practical. If fertilizer is expensive, every pound needs a job. Tracking corn by GDU and leaf collar stage helps identify when the crop is approaching rapid nitrogen demand, and sidedressing can be one of the better tools for matching supply with that demand. Done well, it can improve efficiency, preserve flexibility, and reduce the amount of nitrogen exposed to early-season loss before the crop is ready to use it.

References

The Earfull May 4, 2026

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Cold Soils, Slow GDUs, and Frost

seed in hand

The last week has not given us many GDUs, and that changes the conversation for a lot of fields. Instead of focusing only on frost burn to emerged plants, the bigger concern in many acres is seed and seedlings sitting in cold soils, waiting for heat. Corn emergence is strongly tied to temperature, and Extension guidance shows that corn typically needs about 90 to 120 GDUs from planting to emergence, with around 125 GDUs often used as a practical benchmark in the Upper Midwest. Residue, fine-textured soils, deeper planting depth, crusting, and cool seed-zone conditions can all stretch that window further.

That matters this spring because many planted fields likely are not far enough along to have much exposed tissue yet. A lot of the risk is still below ground. Fields planted earliest, fields on lighter ground, or fields with warmer seedbeds may have some emerged corn or soybeans, but broad acres are more likely sitting in a delayed emergence pattern than in a true frost-leaf-burn situation. That is why this week is a good time to remind us that a slow start does not automatically equal a failed start.

For fields that have not emerged, the first step is to dig, not guess. Check seed and seedlings in several spots across the field, especially where soils differ. Healthy seedlings should still be firm, light colored, and progressing normally. Trouble signs include seed that is soft, discolored, or leaking; mesocotyls or hypocotyls that are brown, water-soaked, or collapsed; and seedlings that are twisted, leafed out underground, or simply not progressing toward emergence. Cold conditions do not always kill a stand, but they do raise the odds of uneven emergence, wider variation in plant size, and more plant-to-plant competition later in the season.

For acres that emerged, crop stage is everything. In corn, leaf tissue may turn brown or black after a frost and still not mean the plant is dead. Corn’s growing point stays below ground until about V5, which gives the crop a level of protection from simple frost. If temperatures fall to truly lethal levels, around 28 degrees or lower for several hours, injury can move beyond leaf tissue and affect the growing point even though it remains below the soil surface. That is the difference between cosmetic injury and real stand loss.

Soybeans are more exposed once emerged because their growing points are above ground much earlier. Frost injury to cotyledons and upper tissue can be more serious in beans than in corn, but soybean recovery is still possible if living buds remain at nodes above the point of fatal injury. If freeze damage extends below the cotyledons, that plant usually will not recover. This is why soybeans often require more careful plant-by-plant inspection after a cold event instead of a quick visual estimate from the field edge.

The main message for this week is straightforward. A lot of fields have not had enough heat to be judged from the road. Dig seedlings, know your stage, and give frosted acres a few days before deciding. Slow emergence is frustrating, but slow does not always mean dead. In many cases, the best management choice is not speed, but patience and accurate scouting.

Pre-Emerge Weed Control

In a spring with slow GDUs and uneven crop emergence, pre-emergence (PRE) herbicides become even more important. Weeds do not need a fully developed crop to create problems, and they often take advantage of slow-starting corn and soybeans before the crop can compete. A strong PRE herbicide program remains one of the most important tools for managing weeds and protecting soybean yield potential, especially as resistance to key post-emergence chemistries continues to spread.

The weather forecast is a major part of whether a PRE program performs the way it should. PRE herbicides generally need rainfall for activation so the active ingredient can move into the soil zone where weed seeds germinate. Most need about 0.25 to 1 inch of rainfall to activate soil-applied herbicides. Many products can remain effective on the soil surface for about 7 to 10 days, with some lasting up to 14 days before activation.

On the other side, too much rain can also create issues. Heavy rainfall near crop emergence can increase the chance of crop response, especially in soybeans and with products or soil conditions already prone to temporary injury. Cool, wet conditions can increase the chance of early-season soybean response from some PRE herbicides, particularly on coarse-textured soils with low organic matter or higher pH. Even though soybeans often recover from minor injury without lasting yield loss, this is still a good reminder that product choice, soil type, and timing all matter.

That is why PRE timing should be connected to both planting date and the short-term forecast. In a cool spring like this one, there may be a little more flexibility in some fields because the crop is moving slowly. But that flexibility can disappear quickly once a warmer stretch arrives. A field that looked several days away from emergence can move faster than expected once soils warm, and that changes both crop safety considerations and the value of getting the herbicide applied before the next activating rain.

In a year like this, good weed control will come from matching the PRE program to the field by field forecast. Put the strongest focus on fields most likely to emerge quickly or fields with the toughest weed history. Then follow with a timely post pass rather than expecting the PRE to solve the entire season by itself. In short, a slow spring does not reduce the importance of pre-emerge herbicides. It probably increases it.

tractor spraying field

Sources

The Earfull April 27, 2026

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Planting Into Marginal Conditions

soil in hand

The planting window always tempts growers to push. The best risks are the ones that preserve stand establishment, not the ones that simply move the calendar ahead. University extension guidance consistently points to soil fit, short-term temperature trend, and emergence uniformity as the main factors that separate a smart early push from a preventable stand.

Corn can justify some early-planted risk when:

  • Seed-zone soil temperature is at or near 50°F.
  • The forecast is warming.
  • The field is fit enough to avoid sidewall smearing or cloddy seedbeds.

In dry conditions, moving seed a bit deeper to reach uniform moisture can be worthwhile.

The risk is usually not worth planting into wet soils, planting just ahead of a cold rain, or planting in rough conditions causing variable seed depth. Corn is especially vulnerable during the first 24 to 48 hours after planting because cold water uptake can trigger imbibitional chilling, leading to weak or abnormal seedlings before the crop ever reaches the surface.

A practical way to frame corn decisions is simple:

  • Take the risk when soils are fit, moisture is uniform, and temperatures are expected to hold or rise.
  • Don’t take the risk when the field is tacky, sidewalls smear, or a cold rain is likely right after planting.
  • Protect yield by chasing uniform emergence more than by chasing the earliest possible date.

Soybeans often reward timely early planting, but only when the first day after planting favors warm water uptake rather than cold shock. Iowa State still recommends planting soybeans into warm soils when temperatures are not expected to decrease during the first 24 hours. This is because the seed is most vulnerable during the first 12 to 24 hours of water uptake.

seedhandlers

The risk potentially worth taking in soybeans is planting early into a fit field with a stable forecast, even if the calendar date feels aggressive. The risk typically not worth taking is planting into cool, wet, or saturated ground where crusting and oxygen stress can nearly wipe out emergence, especially in low areas or fields with uneven drying.

For both crops, the main question is not “Can the planter run?” but “Will the stand emerge evenly?” Corn pays a bigger penalty for uneven emergence, while soybeans generally tolerate stand variability better — unless gaps become large or emergence failures are severe.

Early Emergence Expectations

Once seed is in the ground, the next job is to separate patience from problems. Cool conditions slow emergence naturally. Scouting should focus on whether plants are progressing normally, uniformity of delays, and if symptoms point to crusting, chilling, disease, or seed-zone variability.

In corn, early emergence should be judged on both timing and uniformity. Purdue’s work shows yield loss grows when emergence spreads out. Full stands containing plants delayed by about 1.5 weeks lose roughly 6 to 8 percent, and delays of about 3 weeks become much more costly, especially when many plants are late.

Scout corn fields for:

corn stalks with roots

  • Uneven height or leaf stage across the row, which often points to variable moisture, temperature, or seed placement.
  • Corkscrewed mesocotyls or underground leafing out after cold stress.
  • Plants trapped below a crusted surface, especially after hard rain on worked ground.
  • Open seed furrows, sidewall compaction, or clod-related skips that trace back to planting into wet soils.
  • A useful rule in corn is that uniform, slower emergence is usually less damaging than patchy emergence. If the whole field is slow because temperatures stayed cool, patience is often warranted; if neighboring plants are emerging far apart in stage, competition begins early and yield risk rises.

Soybeans deserve a different lens. Iowa State notes soybean cold injury can reduce vigor or kill seed before emergence, but soybean stands often tolerate some unevenness better than corn unless plant loss creates large holes.

Scout soybean fields for:

  • Missing plants tied to seed death before emergence in cold, wet soils.
  • Pale seedlings, slow hypocotyl pull, or emergence blocked by crusting.
  • Swollen, weak, or rotted seedlings that suggest disease pressure in saturated conditions.
  • Large gaps, especially those greater than about 2 feet, as this could lead to higher pressure later in the year.

Soybean emergence evaluation should emphasize surviving stand and gap pattern more than perfect visual uniformity. Iowa State notes soybean emergence uniformity very rarely causes enough yield loss by itself to justify replanting. Instead, the key is to confirm that enough healthy plants are present and the stand can canopy and compete.

Scouting priority for both crops:

Dig plants rather than guessing from the road. The first pass should check seed depth, moisture pattern, mesocotyl or hypocotyl condition, crusting, and whether the problem is random or tied to a soil type, tillage pass, residue band, or low spot.

Sources

The Earfull April 20, 2026

PDF Version

Early Season Insects—What to Look For

Planting season moves fast. By the time a stand problem is obvious, the window to act — or to explain it — has already closed. Early-season insects are one of the most common causes of uneven emergence, skips, and replant decisions, and they’re easy to miss if you’re not scouting at the right time.

Risk isn’t tied to one type of spring. Cool, wet soils slow germination and leave seeds in the ground longer, giving soil-dwelling pests more time to feed. But warm soils with heavy crop residue, manure applications, or recently terminated cover crops create their own risk by drawing egg-laying insects and supporting larval populations. Both scenarios show up regularly across the Renk sales area. Walking fields at or shortly after emergence — not just at canopy closure — is when these problems are catchable and explainable. Let’s review the key pest offenders:

Seedcorn Maggot (Corn and Soybeans)

seedcorn maggot injury on soybean plant

Seedcorn maggot is the larva of a small fly — pale yellow-white, legless, about ¼ inch long. Larvae feed directly on germinating seeds and young shoots before the plant ever breaks ground. Fresh organic matter is the main attractant. Fields with heavy residue, recent manure, incorporated cover crops, or freshly tilled green material carry the highest risk. Cool, wet soils compound the problem by slowing germination and extending the window larvae have to feed.

In the field, look for seeds that are hollowed out or show no viable shoot or root development. You’ll often find seedlings that started to emerge and then died at or just below the soil surface. Gaps and skips that don’t match planter performance data are a telltale sign, particularly in low-lying areas, field edges near manure application zones, or anywhere a cover crop was terminated late.

Wireworm (Corn and Soybeans)

wireworm

Wireworms are the larvae of click beetles — hard, shiny, orange-brown, and cylindrical, almost wire-like to the touch. They spend multiple years in the soil and feed on seeds and below-ground plant tissue. Sod ground is the classic red flag: former pasture, fields following small grains or perennial grasses, or any ground that’s been in long-term grass cover. First-year corn or soybeans after sod is the highest-risk scenario you’ll encounter.

Stand loss from wireworm tends to be patchy and irregular — not clean row skips, but odd sections or scattered holes in the field. Seeds will show entry holes or be hollowed out with the shoot or radicle chewed off. To confirm, dig 6 to 12 inches deep in problem areas; early in the season when soils are still cool, wireworms concentrate in the top few inches. Stunted, wilted, or dead seedlings where the underground stem is damaged, but the plant never fully emerged are a reliable indicator.

Black Cutworm (Primarily Corn; Occasionally Soybeans)

black cutworm

Black cutworm moths don’t overwinter in most of the Renk sales area — they migrate north on spring storm systems. Fields with winter annual weeds, heavy surface residue, or recently terminated cover crops are higher risk because they attract egg-laying moths. Corn from VE through V5 is the primary target. Soybeans can occasionally be clipped in a heavy year, but this is mainly a corn problem.

Watch for wilted or cut-off plants at or just below the soil surface, often in the first few rows from field edges or in weedy areas. Damage shows up in clusters or patches, not uniformly across the field. Before full cutting begins, you may see small, round feeding holes in leaves — that’s your early warning. When you find damage, dig in moist soil near the affected plants and look for the caterpillar itself: dark gray to black, curls into a C-shape when disturbed.

In soybeans, if pressure is unusually high, check for clipped stems or leaf feeding on early-emerged plants along field edges or in areas with residue. It’s uncommon, but worth a look in high-pressure years.

Quick Risk Overview:

No single field type has zero risk. The combination of field history — sod, cover crops, manure — residue levels, weed pressure, and spring weather determines where problems concentrate. Cool springs push seedcorn maggot and wireworm risk up. Warm springs with weedy fields and migrating storm fronts elevate black cutworm. Many fields carry more than one risk factor.

Take Home:

  • Walk fields at emergence. Target fields with manure, high residue, cover crop history, sod ground, or known weed pressure first — these are your highest-risk acres.
  • Dig before you diagnose. Skips and uneven emergence have many causes. Pull seeds and seedlings from problem areas and look for physical damage before attributing stand loss to cold stress or planter issues.
  • Document what you find. Note field history, soil conditions, pest species observed, and estimated stand loss.

Early planting into cold soils increases seedcorn maggot and wireworm exposure. Late cover crop termination increases all three pest risks.

Sources:

The Earfull April 13, 2026

PDF Version

Corn Seedling Diseases: When Mother Nature Overwhelms Even the Best Treatments

row of corn seedlings

Renk Seed corn comes standard with industry-leading multi-mode seed treatment packages Metalaxyl, Fluoxastrobin, and Prothioconazole working together to protect your seedling from the moment it hits the soil. But some springs, Mother Nature tips the scales. Extended cold and wet soils after planting, or a warm saturated stretch right after emergence, can push disease pressure beyond what the seed treatment alone can fully hold back. That’s exactly why we introduced Resilient™ AP,
a planter box biological treatment designed to layer additional protection right at seeding, reinforcing root health and early vigor when conditions get tough.

The Three Main Corn Seedling Diseases

Pythium — The most common early-season threat. Thrives in cool, saturated soils (below 55°F) with standing or pooled moisture. Produces swimming spores that move through wet soil directly to the root. Infected seedlings have dark, slimy roots where the outer cortex peels away, leaving a white inner core. Seed that never emerged will be soft and rotted. Concentrated in low spots and poorly drained areas.

Fusarium — The opportunist. Covers a wider range of temperature and moisture conditions and follows plant stress, compaction, herbicide injury, temperature swings, or saturated soils. Shows up as tan to reddish-brown lesions on the mesocotyl and roots, sometimes with pink or salmon sporulation. Stressed plants invite it in; a clean planting environment keeps it at bay.

Rhizoctonia — The dry-side problem. Unlike the others, Rhizoctonia favors warmer, drier conditions and hits hardest in sandy or well-drained loam soils. Infected seedlings have firm, dry, reddish-brown lesions on the mesocotyl near the soil line, not mushy, not water-soaked. Often no obvious above-ground symptoms until the plant is stunted or chlorotic.

Resilient™ AP: Our planter box biological treatment adds beneficial microorganisms directly at seeding, colonizing the rhizosphere to compete with soilborne pathogens and support root development, extending your protection window beyond what the fungicide chemistry alone covers. In its launch year we will not have any additional supply for in-season needs.

How to Scout Corn Seedlings

Scout at emergence through V2, that’s your window before the plant either recovers or the evidence disappears. Walk problem areas and pull 10–15 plants where healthy plants transition into gaps or stunted ones.

  • Examine the mesocotyl (stem between seed and soil surface) and root system after a light rinse.
  • Healthy tissue is white and firm, any tan, brown, reddish, or black coloration is a red flag.
  • Try peeling the outer cortex of the root. If it slides off leaving a white center, that’s Pythium.
  • Firm, dry, reddish lesion at the soil line = Rhizoctonia. Mushy dark tissue = Pythium or Fusarium.
  • Pythium concentrates in wet low spots. Rhizoctonia is more common on lighter, sandier soils.

Soybean Seedling Diseases: Why We Built the Defender Treatment Program

Soybeans can compensate for a lot, but they can’t compensate for plants that never made it. Soybean seedling diseases are one of the most common causes of stand loss in the Midwest, and the pathogen complex is more diverse than corn. That diversity is exactly why Renk offers the Defender treatment program. A single active ingredient isn’t enough when your field can throw Pythium, Phytophthora, Rhizoctonia, or Fusarium at you depending on soil temperature, drainage, and field history. Defender brings together the right chemistries to address these diseases.

The Four Soybean Seedling Diseases to Know

Pythium — Most common in the northern Corn Belt. Favors cool, saturated soils (50–77°F) and attacks quickly, before germination or right after emergence. Infected seeds are soft and rotted. Emerged seedlings have water-soaked lesions on the hypocotyl and cotyledons, pull from the soil with almost no resistance, and show poorly developed roots. Follows the wet spots in a field.

Phytophthora — Field-history-specific and warm-weather driven (>60°F soils + wet). Once it’s in a field, it comes back to the same low spots and high-clay areas when conditions repeat. The tell is a chocolate-brown discoloration that runs from the root up the stem, sometimes 6+ inches above the soil line, while the interior stays firm. After V2, this stem signature separates it cleanly from Pythium.

Rhizoctonia — Warm, drier conditions and sandy or south-facing soils. The lesions are firm, dry, and reddish-brown on the hypocotyl near the soil line, never mushy. Worth noting: a Rhizoctonia seedling infection that goes unnoticed in May can resurface as plant snap-off during summer wind events when the cortical rot weakens the stem base.

Fusarium — Follows stress, compaction, flooding, temperature swings, herbicide pressure. Causes brown to black root discoloration, but plants often stay standing with reduced vigor rather than dying outright. That makes it easy to miss and easy to blame on something else.

Quick Diagnostic Guide: Mushy, water-soaked tissue = Pythium or Phytophthora. Brown running up the stem above soil = Phytophthora specifically. Firm, dry reddish lesion on hypocotyl = Rhizoctonia. Brown-black root staining, plant still standing = Fusarium.

How to Scout Soybean Seedlings

Your scouting window is emergence through V2. After that, surviving plants are largely past the worst of the seedling disease risk, but the evidence of what happened is fading fast.

  • Pull 10–15 plants from the edge of a problem area and examine the hypocotyl and roots.
  • Check the soil line first, the classic Phytophthora brown line moves up the stem from the root.
  • Mushy roots with no structure = oomycete. Firm reddish lesion on hypocotyl = Rhizoctonia. Brown-black lower root staining = Fusarium.
  • After V2: Phytophthora shows stem discoloration above the soil line; Pythium damage stays at the hypocotyl and below.
  • Count your stand, a final stand below 80,000 plants/acre (narrow rows) or 100,000 plants/acre (wide rows) costs yield. Run the math before replanting into June.
  • Use a hand lens: Fusarium often shows pink-salmon tissue coloration. Phytophthora does not, it stays brown to tan.

Sources

  • Crop Protection Network. “An Overview of Soybean Seedling Diseases.” cropprotectionnetwork.org (2026).
  • University of Nebraska–Lincoln CropWatch. “Conditions Favor Seedling Diseases in Early Planted Corn and Soybeans.” cropwatch.unl.edu (2022).
  • University of Wisconsin Extension. “Seed Treatment Fungicides — Corn and Soybean.” fyi.extension.wisc.edu (2010).

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