Angie Peltier, UMN Extension crops educator, Jeff Coulter, UMN Extension corn agronomist and Seth Naeve, UMN Extension soybean agronomist
The following information was provided during a 2025 Strategic Farming: Field Notes session. Use your preferred podcasting platform or listen online to a podcast of this Field Notes session hosted by UMN Extension crops educator Liz Stahl.
Very warm temperatures throughout most of May meant that germinating seeds accumulated enough heat units to emerge very quickly – in as few as 6 days after planting in some instances.
When assessing corn stands, evaluate plant spacing. Within-row plant spacing doesn’t have much of an effect on corn yield, so long as there are not large gaps. Research has shown that gaps of 16 to 33 inches can reduce yield by 2%, while gaps of 4 to 6 feet reduce yield by 5%. These yield reductions need to be deducted from the projected yield potential based on the overall plant population.
When replanting corn between May 22 and 28, shift to planting a hybrid that is 5-7 relative maturity units earlier than what would be considered a full-season maturity for your area. When replanting between May 29 and June 4, shift to a hybrid that is 8-15 relative maturity units earlier. When replanting between June 5 and 10, select a hybrid that is 15 or more relative maturity units earlier than full season.
A full third of Minnesota’s soybean crop got planted in the week before the rainy weather. UMN Extension soybean agronomist Seth Naeve said that the combination of early planted soybeans and unseasonably HOT temperatures have led to his seeing soybeans that are more uniform and farther along, developmentally-speaking, as he has ever seen them at this point in the growing season.
The key to a good soybean crop isn’t just a timely planting date, but also quick seedling emergence after planting. The date of emergence marks the beginning of the effective growth cycle for soybeans. Time spent emerging does not add to a soybean crop’s yield, and has the opportunity to contribute to disease problems later in the season.
For example, research has shown that earlier infections by the pathogen that causes sudden death syndrome in soybean (Fusarium virguliforme) are more likely to reach a plant’s vascular system resulting in greater disease severity and associated yield loss. The likelihood of severe foliar sudden death syndrome symptoms and early maturity due to disease increases the longer the seed is sitting in the soil before emergence.
In some areas of the state, corn crops that have been sandblasted look similar to the aftermath of a frost or hail event. Until the corn crop has developed 5 leaf collars, its growing point remains below ground, meaning that although the crop may have been impacted by sandblasting (or a frost), if one digs down and still encounters living tissue, the crop is very likely to regrow.
In some sandblasted fields as new leaves are formed on the inside of the corn whorl, damage to the outermost leaves can result in that leaf tissue dying while still remaining attached to the plant and wrapped around the younger leaves, creating a ‘buggy whip’ appearance. As temperatures warm and corn continues to develop, the growth of the younger leaves should progress and eventually break through the dead tissue to grow normally. Yield loss from sandblasting should be minimal in corn, and no more than a couple percent.
Soybean stands should also be assessed, particularly if one worries that there may have been sandblasting injury. As the soybean plant’s growing point is above ground, when making stand assessments, if no remaining green tissue is observed at or above the cotyledons, it is safe to assume that the plant is dead. If any area of the field has a soybean stand below 80,000-100,000 plants per acre, those areas of the field have been set up for lower yields. Some consideration should be given to supplementing the existing stand with additional seeding or replanting those areas of the field.
Thanks to the Minnesota Soybean Research and Promotion Council and the Minnesota Corn Research and Promotion Council for their support of this program.
Planting progress
Although the recent rains are delaying field work and -despite going gangbusters before a drop of rain fell- we are feeling behind, we actually aren’t behind! According to USDA’s National Agricultural Statistics Service, as of May 19, 2025 the Minnesota dent corn crop was 92% planted and 58% emerged. This is a full 10 days ahead of the 5-year average for planting progress and 6 days ahead of average emergence. Soybean progress is much the same, with 81% of Minnesota’s soybeans planted and 32% emerged. Soybean planting is 10 days earlier and emergence 6 days earlier than the 5-year average.Minnesota’s 2025 corn crop
Some farmers in southern Minnesota were able to take advantage of warmer temperatures and fit soil conditions to get their corn planted during April 11-16, the earliest planting window available in 2025. However, wet conditions and cold soil temperatures negatively impacted some corn stands and led to some of this earliest planted corn needing to be replanted – especially when following corn with reduced tillage, on fine-textured soils. Farmers weren’t able to get back into fields until ~May 5, with tillage, fertilizer applications, planting and pre-emergence herbicides all taking place at once ever since.Very warm temperatures throughout most of May meant that germinating seeds accumulated enough heat units to emerge very quickly – in as few as 6 days after planting in some instances.
When assessing corn stands, evaluate plant spacing. Within-row plant spacing doesn’t have much of an effect on corn yield, so long as there are not large gaps. Research has shown that gaps of 16 to 33 inches can reduce yield by 2%, while gaps of 4 to 6 feet reduce yield by 5%. These yield reductions need to be deducted from the projected yield potential based on the overall plant population.
Corn stand assessments and replanting decisions
As soon as you can row a corn crop from the road, it would be time well-spent to go out and assess your crop’s stand from multiple spots in the field. An insufficient stand can reduce yield potential by resulting in fewer ears in the end due to fewer plants, not maximizing the area of the field covered with green, photosynthesizing tissue and by not shading out weed seedlings that will eventually compete with the crop for limited resources. The UMN Extension website has information about how best to assess a corn stand and how to consider replanting decisions. One needs to consider the yield potential of the current crop given its plant population and planting date and then compare it to the yield potential given a better stand but later planting date. In general, when corn plant populations are below ~20,000 plants per acre, one should consider replanting the crop. However, each Minnesota corn producer knows their own cost of production and so should make any replant decision using their own economic reality.Adjusting corn maturities
A replanted crop will be behind in growth and development compared to a crop that has already emerged. Therefore, it is important to adjust relative maturity when replanting to increase the likelihood of the crop being able to reach physiological maturity naturally and not risk dockage due to poor test weight. Running a corn drier is also a costly endeavor and so it is important to best take advantage of warm fall temperatures to allow some in-field grain drying to take place.When replanting corn between May 22 and 28, shift to planting a hybrid that is 5-7 relative maturity units earlier than what would be considered a full-season maturity for your area. When replanting between May 29 and June 4, shift to a hybrid that is 8-15 relative maturity units earlier. When replanting between June 5 and 10, select a hybrid that is 15 or more relative maturity units earlier than full season.
Minnesota’s 2025 soybean crop
Work at the Southwest Research and Outreach Center in Lamberton by IPM specialist emeritus Bruce Potter looking at soybean planting date over a 25 year period showed lost yield potential of only about 0.2% per day, or 2% for each 10-day delay in planting. This is for a full-season maturity variety adapted to the region and equates to a 1 to 1.5 bushel advantage to planting earlier compared to 10 days later, meaning that overall there is not much of an advantage to early planting. Early planting of a shorter season variety than is adapted to the area will reduce the yield advantage conferred to early planting. Other crop production challenges that the crop experiences throughout the growing season can also erase any early-planting yield advantage.A full third of Minnesota’s soybean crop got planted in the week before the rainy weather. UMN Extension soybean agronomist Seth Naeve said that the combination of early planted soybeans and unseasonably HOT temperatures have led to his seeing soybeans that are more uniform and farther along, developmentally-speaking, as he has ever seen them at this point in the growing season.
The key to a good soybean crop isn’t just a timely planting date, but also quick seedling emergence after planting. The date of emergence marks the beginning of the effective growth cycle for soybeans. Time spent emerging does not add to a soybean crop’s yield, and has the opportunity to contribute to disease problems later in the season.
For example, research has shown that earlier infections by the pathogen that causes sudden death syndrome in soybean (Fusarium virguliforme) are more likely to reach a plant’s vascular system resulting in greater disease severity and associated yield loss. The likelihood of severe foliar sudden death syndrome symptoms and early maturity due to disease increases the longer the seed is sitting in the soil before emergence.
How have recent high winds impacted the crop?
The dry fall 2024 through spring 2025 and recent very windy weather have led to crop injury due to sandblasting. In general, the drier the soil conditions, the higher the wind speed, the smoother the soil surface and the less residue left from previous crops, the greater the risk of sandblasting injury or sandblasting leading to crop failure and a need to replant.In some areas of the state, corn crops that have been sandblasted look similar to the aftermath of a frost or hail event. Until the corn crop has developed 5 leaf collars, its growing point remains below ground, meaning that although the crop may have been impacted by sandblasting (or a frost), if one digs down and still encounters living tissue, the crop is very likely to regrow.
In some sandblasted fields as new leaves are formed on the inside of the corn whorl, damage to the outermost leaves can result in that leaf tissue dying while still remaining attached to the plant and wrapped around the younger leaves, creating a ‘buggy whip’ appearance. As temperatures warm and corn continues to develop, the growth of the younger leaves should progress and eventually break through the dead tissue to grow normally. Yield loss from sandblasting should be minimal in corn, and no more than a couple percent.
Soybean stands should also be assessed, particularly if one worries that there may have been sandblasting injury. As the soybean plant’s growing point is above ground, when making stand assessments, if no remaining green tissue is observed at or above the cotyledons, it is safe to assume that the plant is dead. If any area of the field has a soybean stand below 80,000-100,000 plants per acre, those areas of the field have been set up for lower yields. Some consideration should be given to supplementing the existing stand with additional seeding or replanting those areas of the field.
How to protect future crops from sandblasting
In future years, there are many things that can be done to reduce the probability that a crop will be sandblasted. Perhaps rethinking whether your 2025 soybean field needs to be tilled this fall or whether one can wait until next spring to prepare the seedbed. Tillage in dry conditions can result in soil becoming powdery and susceptible to wind erosion. A lot of the disk-ripper and field cultivator implements have rolling baskets, also referred to as “crumblers”. These crumble the soil into smaller particles, thereby destroying the soil structure that acts to keep soil from being lost to wind erosion. This can be especially problematic in fields with low amounts surface residue. Additionally, some of the soils in western Minnesota that have a high calcium carbonate content do not form soil aggregates as easily as other soils and are therefore more inherently susceptible to wind erosion. In these situations, reducing tillage and leaving as much residue as your planter can handle are particularly important steps to reduce the risk of wind erosion.Wind erosion can also cause loss of fertilizer and pre-emergence herbicides applied to the soil
Audience questions
Naeve and Coulter answered numerous audience questions including, “How large can gaps be in the corn or soybean stand without resulting in lost yield potential?”, “In a year like 2025 when warm temperatures allowed crops to emerge very quickly, was the value of a fungicidal seed treatment diminished?”, “With daylength-sensitive plants, how early can we expect soybean harvest to start?”, “Tar spot showed up early last year in many states. Any thoughts about watching and treatments this year?”, “Isn’t surface roughness also a factor that can impact wind erosion?.Thanks to the Minnesota Soybean Research and Promotion Council and the Minnesota Corn Research and Promotion Council for their support of this program.
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