Corn Replanting Guide

NK Corn Replanting Guide


Soybean Replants

Contributed by Robert Moloney, NK Brand Seeds

There are not a lot of soybean replants happening but there are a few fields (mainly planted in the Apr 30-May 2 timeframe) that are being replanted. This appears to be due to a combination of the beans just running out of steam and some level of crusting.

The key factors to look for if you are concerned about your field:
– if your beans have excessive swelling just below the crook of the seedling (i.e. it is swollen significantly just below the crook compared to the rest of the stem down to the root) this can indicate bean is trying to grow, but being stopped by a crust. Once the beans have a lot of this swelling they won’t be able to continue growing up.
– if your beans are starting to leaf out underground or the cotyledons are being snapped off as they try to push through the crust (bald beans) those plants are likely done.
– do you have a minimum 100,000 plants/acre? If you have this many healthy plants emerged you likely won’t increase yield enough by replanting to cover the cost of replanting.

To calculate your plant stand:

For 7” rows: in 7” rows it is easiest to use a hula-hoop and count the number of bean plants inside it. Below the factor to multiply the number of plants you count by to get a number per acre (based on the diameter of your hula-hoop). Make sure you check in a number of spots across the field and get an average population count.

EXAMPLE: if you have a 30” inside diameter hula hoop and you count an average of 12.5 plants inside it over a number of spots in the field, your plant stand is approximately 12.5 X 8,874 = 110,925 plants/acre and you are likely better off to leave the field than replant it.

For 15”, 20” or 30” rows: personally I prefer to count plants per foot of row on wider row spacings. There is too much variation depending where your hula hoop lands on the rows (even in 15” rows) with the hula hoop. You can use the factors below to get a plants per acre number. Make sure you check at least 10-15 feet of row in a number of places over the field.

EXAMPLE: if in your 15” rows beans you average 2.1 plants/foot so your stand is 2.1 X 34,848 = 73,180 plants/acre.  At this population you would want to re-plant or thicken the stand.

Make sure you do an actual plant count rather than just a visual assessment before deciding what to do. On a marginal stand appearances can be quite deceptive. It’s worth getting a 2nd opinion from your NK dealer if you have a field you are concerned with.

Hot Days and Warm Nights

Contributed by Clare Kinlin, Regional Manager, Eastern Ontario

Wow!!! What a spring! Ideal planting conditions, adequate soil moisture with warmer temperatures in the forecast has made this season one to remember. The crop is developing nicely considering the frost and cooler temperatures last week. Lack of soil moisture for soybean planting is starting to be a concern in some areas that have missed a few of the showers lately. .
Soybeans need to be planted into moisture (no deeper than 2.5 inches); Rolling or packing behind will help maintain soil moisture but will not create soil moisture. We only want to plant the field once, it is important to get it right the first time. Picture inserted is April 30th planted soybeans in Eastern Ontario
The corn picture is from a field of corn that was not emerged went the frost occurred, as you can see the first emerged leaf (Plumule) is still intact. However many fields that was emerged before the frost often the plumule and possible the second emerging leaf are destroyed and missing. Although this corn looks UGLY with twisted leaves and struggling due to the stress of the frost there will be little to no impact on yields. Ear size (yield) is not determined to much later in the season. Now is the time to check your stand for emergence.

Early soys: they’re slow, but they’re coming

Contributed by: Robert Moloney, NK Brand Seeds

Some soybeans managed to get planted in the end of April to start of May timeframe before the rain and cold weather set in.  Now a lot of those fields have been in the ground for 3 weeks or more and they still haven’t emerged yet.  Should you be concerned?  The short answer in most cases is “no, you shouldn’t be concerned”.  Based on early planted fields I’ve looked at, the beans are still healthy and coming, they just need some heat to get them out of the ground.

Why aren’t they up yet?  Look to the weather we had in the first part of May.  Our May weather seemed start out as the April weather we never got.  Generally across the southwestern part of the province it was cool and damp (Eastern Ontario was warmer and drier).  Fortunately most of the early beans were planted into good soil conditions and the soil was still warm when they were planted and through early germination.  The cool weather since then seems to have put the germinated seed on ice and kept it from growing much.  The one positive was that it was generally too cold for seedling diseases or much insect activity to cause damage.  The cool weather that slowed plant development is likely most of these fields have been slow emerging.

If you are concerned about your beans, the key thing to do is to dig up some beans and check them out.  Healthy beans are going to be firm and white.  You can get some green or green/purple/red on the top parts once they are exposed to light.

Healthy soybean seedling

The cotyledons (the 2 halves of the seed) will point downward until the growing stem pulls them out of the ground, then they will flip up and grow on.  Small holes in the cotyledons can be a sign of insect feeding, but unless the growing point (at the end of the cotyledons where they attach to the stems) is affected, the plant will likely survive.  Significant browning (ignore dirt on the root) or a mushy feel to the stem or cotyledons is not a good sign and indicates the seedling likely won’t survive.

Crusting could be a concern in some fields after the rains we’ve had.  Just remember that beans can push through an awful lot (especially in 15” or 30” rows where the plants are closer together and can help each other push out).  If you feel you need to do something about a heavy crust, running an empty no-till drill over the field will probably do more good than a rotary hoe.  If the crust is tough enough to impede the beans, the rotary hoe likely won’t crack it either.  Make sure you check where the beans are at before you try either option though, as beans that are just knuckling through the ground are very susceptible to being snapped off and killed.  There are two common signs that crusting is causing the seedling beans a problem: 1 – if your beans have excessive swelling just below the crook of the seedling (i.e. it is swollen significantly just below the crook compared to the rest of the stem down to the root) this can indicate bean is trying to grow, but being stopped by the crust.  Once the beans have a lot of this swelling they won’t be able to continue growing up.  The 2nd sign is if the beans that are starting to leaf out underground.  This usually follows swelling and at this point the seedling likely won’t survive.

Soybean seedling leafing out underground

So if your bean seedlings are still firm and white, the stems aren’t swelling and you don’t have a severe crust you should be good.  All you can (and should) do is to sit back and wait for the warm (hot) weather to let your beans get growing.

Tips for “later” planted corn

Contributed by Robert Moloney, NK Brand Seeds

It isn’t really “late” by the calendar in most areas yet, but with the amount of corn that has been planted already it feels like it is.  A few things to keep in mind if you’re planting corn in the next couple of weeks:

SWITCHING MATURITY: it’s still too early think about changing in most areas until we get to May 20th -25th depending on what part of the province you are in.  Most years you are going to lose more in yield from shortening maturity than you gain in lowering harvest moisture until you get really late.  After last fall, most growers likely aren’t pushing maturity with the corn they ordered anyway.

SEEDING RATE: don’t drop your seeding rate back just because you’re planting into a warmer seedbed.  The seed treatments we use these days mean we don’t lose many plants in cooler soils anyway, so if you are getting better results from higher seeding rates in early planting, you’re still likely to get a benefit even if it’s later planted.  Check the recommended seeding rate for the hybrid you are planting and keep it to appropriate levels to maximize your yield potential.

PLANTING DEPTH: CHECK IT REGULARY and keep it to a minimum of 1.5” deep.  Planting shallower won’t get it out of the ground much faster and has all kinds of potential to cause you issues.  Planting depth is something that still doesn’t get enough attention paid to it.  Check it in each field and each time soil type or conditions change within a field.

MAKE SURE THE SOIL IS FIT FOR PLANTING: now that we are into a later planting timeframe the temptation is going to be to just get the crop in as soon as you can.  More often than not it will pay to wait the extra day for conditions to improve rather than put it in wet and fight sidewall smearing, compaction and a poor root system all season.

SOIL FERTILITIY: if your soil test levels are low find a way to get the fertilizer on.  You can’t maximize you’re yield potential if you don’t have the nutrients in the ground.  If you have medium to high soil test levels at this point with warmer ground you are less likely to have a response from a banded starter fertilizer, so if time is tight you may not lose much from skipping it.  If soil levels are low you can’t get away with not applying fertilizer if you want to maximize return. 

BURNDOWN: make sure the field is clean before the corn emerges, whether that is through pre-plant tillage or a Touchdown burndown.  Having the field clean before you plant (or at least before the corn emerges) is critical to maximizing yield potential.

Post-frost stand assessment

Contributed by Robert Moloney, NK Brand Seeds

While I don’t expect that there will be a lot of fields with a significant number of plants killed by the May 9/10 frost, there will probably be a few low lying or muck fields with some stand loss. Since it’s still (relatively) early in the planting season some growers may be wondering if it’s worth replanting the field. Here are some points to consider:

1- get an idea of how many plants are dead or so severely damaged that they won’t come back (see previous articles). By now you will likely be able to see some signs of new growth on plants that are recovering. While the dead leaves may cause some leaf trapping, most of the time the plant will push through it given some time.

2 – do you still have an even stand? Moderate damage spread evenly through the stand may have more yield potential than less damage that leaves 3-4 foot gaps in the row. Depending on the field layout it may also make sense to replant only worst damaged part of the field.

3 – what plant population do you have remaining? Count 1/1000th of an acre and multiply by 1,000 in a number of spots to get an average population for the field.

Once you have a population estimate and if the stand is reasonably even over the whole field, the following table will give you an idea of what yield potential to expect with different combinations of planting date and final plant stands. Realize that these numbers are an estimate and will be influenced greatly by a number of factors other than final population and planting date (see below).

As an example if you planted on April 25th expecting a yield of 150 bu/ac and ended up with a final stand of 15,000 evenly spaced plants per acre after the frost, your yield potential is likely 150 bu/ac X 79% = 118.5 bu/ac. If you replant on May 19th and end up with a final stand of 30,000 plants/ac your yield potential is 150 bu/ac X 97% = 145.5 bu/ac. This means that theoretically if you can replant for less than the value of 27 bushels of corn (144.5 – 118.5 = 27 bushels) you should come out ahead.

This chart is a really simplified calculation that doesn’t take into account all the factors involved in replant. Some other things to consider:
– later planting increases the risk of higher moistures/higher drying costs at harvest.
– later planting exposes you to more risk of a fall frost damaging the crop before maturity (potentially resulting in higher drying/lower grades).
– if you move to a shorter maturity hybrid for the replant you will likely give up yield potential versus the longer maturity hybrid you originally planted.
– if the current planting conditions aren’t as good as the original (and this year it would be pretty tough to beat the early conditions), you may give up yield potential because of this.
– if it turns into a dry summer the earlier planted corn will likely have a better root system to deal with drought conditions.
– don’t forget to include the cost of killing the original stand. Thickening won’t work well in corn most of the time due to maturity differences and the fact that the uneven staging between the original plants and the replant plants means both stands become a weed to each other.
– pay attention to any herbicides that may have been applied already. Depending on the product you may end up with crop damage or loss of residual control from any tillage or coulters on the planter from a replant.

Since making a decision on a frosted (or otherwise damaged crop) can be an emotional issue, make sure you get a second opinion from your NK dealer or another competent authority before you do rip up the original stand. While it may look ugly, often the 1st stand will result in you coming out ahead at harvest.

Early Planting, Cold Nights

Contributed by Clare Kinlin, Regional Manager, Eastern Ontario

The ideal planting conditions during the month of April and early May has the crops in Eastern Ontario set-up to be of the highest yield potential ever. These early planting conditions have come with some risk of early season frost and cold temperatures. Over the growing season it will be my attempt to follow the crop from planting to harvest in two particular locations in Eastern Ontario. These two locations are both resourced with Weather Stations, Corn, Soybean plots and lots of photos. I hope to provide you with some insight to crop development and physiological effect that the weather is having on the crops. The frost event on May 10th had an air temperture of -4.1 but a soil temperature of 2.8 C and at Dunvegan.

To assess the impact of freezing temperatures on emerged corn, check plants a few days after freezing temperatures (Corn Tissues Freezes at -2 C). New leaf tissue should be emerging from the whorl. You can also check the growing point (usually located ½ in to ¾ in below the soil surface) by splitting seedlings lengthwise. If the growing point appears white to light yellow and firm a few days after the frost, prognosis for recovery is excellent. In picture below notice the brown tip of the seedling is frost damaged but the growing point is white and alive.

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