,

Why am I seeing Tillers in my Corn?

I have been receiving a few calls over the season regarding tillering in corn. So I figured a Crop Chatter post based on an article I wrote back in 2005 would be good to answer some questions. Is it only due to plant populations? What could be other causes? What effect will tillering have on crop growth and yield potential?

What are Tillers? And What Causes Them?  Tillers are lateral branches that form at below ground nodes. Although tiller buds form at each below ground node, the number of tillers that develop is determined by plant population and spacing, soil fertility, early season growing conditions, and the genetic background of the hybrid.

  • Plant Population: Many hybrids will take advantage of available soil nutrients and moisture by forming one or more tillers where stands are thin in the row or at the ends of rows. However, excessive tillering may indicate problems with stand density and distribution. If tillering is associated with row gaps and less than optimal plant populations, these are the conditions which need to be corrected to ensure optimal yields.
  • Soil Fertility: Tillers are most likely to develop when soil fertility and moisture supplies are ample during the first few weeks of the growing season. They are usually visible by the 6-leaf stage of development.
  • Genetics: Hybrids with a strong tillering trait may form one or more tillers on every plant even at relatively high populations if the environment is favorable early in the growing season. If a particular hybrid shows excellent yield potential and also produces extensive tillering under some growing conditions, it should not be avoided.
  • Weather Conditions: Hail, frost, and flooding injury that destroy or damage the growing point early in the growing season can also result in tiller development and non-productive plants.

What is the Effect on Yield Potential? When farmers see extensive tillering in their corn hybrids, they often express concern that the tillering will have a detrimental effect of crop performance (that the tillers will “suck” nutrients from the main plant and thereby reduce yields). As a result, tillers are often referred to a “suckers”. However, research has shown that tillers usually have little influence on grain yields and what effects they do have are generally beneficial. Recent studies have found that there is little movement of plant sugars between the main plant and tillers before tasselling.

After silking and during grain fill, substantial amounts of plant sugars may move from earless tillers to ears on the main plant. When there are ears on both the tiller (often called ‘tassel-ears’) and the main plant, little movement of plant sugars occurs. The main plant and tillers act independently, each receiving sugars from their own leaves. The ‘tassel-ears’ that tillers may produce, therefore have no impact on the ear development of the main plant as was once thought and don’t contribute to yield.

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

Manitoba Agriculture website: www.manitoba.ca/agriculture
Manitoba Agriculture on Twitter: @MBGovAg
Manitoba Agriculture on YouTube: www.youtube.com/ManitobaAgriculture
Respond
Have a follow-up question?
,

Manitoba Insect & Disease Update – Issue 10: July 20, 2016

The Manitoba Insect and Disease Update is now posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/insect-report-2016-07-20.html

Some highlights from the update:

Insects:

  • Pea aphid levels are still a concern in some pea fields, although many fields will be getting to the stage where management would no longer be economical.
  • Aphid levels have dropped in many cereal fields where previously levels had been increasing. High levels of natural enemies have been noted in some of these fields, and some intense rains may have also contributed.
  • In some areas of Central and Southwest Manitoba, greater than 90% of the wheat midge are expected to have emerged. In many areas of Manitoba about 50 to 90% of wheat midge are expected to have emerged. A reminder that wheat that has already produced anthers is no longer susceptible to feeding by wheat midge. Even if adults are still active in these more advanced fields, the larvae will not feed on the grain.
  • Egg masses of European corn corer are starting to be noted in some fields of corn. So far there are no reports of high levels, but now is the time to be checking fields for the egg masses.
european-corn-borer-egg-masses

Figure 1. Egg masses of European corn borer.

Plant Pathogens:

  • Some infections of blackleg in canola and fusarium head blight in cereals have been reported.
  • A few cases of loose smut in barley were also reported.
  • Two positive identifications of Goss’s Wilt in corn were made. The positive identifications were made based on immunostrips and/or polymerase chain reaction (PCR) assays.

Submitted by: John Gavloski, Entomologist & Pratisara Bajracharya, Field Crop Pathologist, Manitoba Agriculture

Manitoba Agriculture website: www.manitoba.ca/agriculture
Manitoba Agriculture on Twitter: @MBGovAg
Manitoba Agriculture on YouTube: www.youtube.com/ManitobaAgriculture

 

Respond
Have a follow-up question?

Hail Damage in Corn & the Impact of Bruising and Stalk Damage

Hail in the recent days have impacted some corn acres in Manitoba.  In an earlier Crop Chatter post (Assessing Hail Damage in Corn), typically yield reduction due to hail damage is a result of leaf loss.

However, there can be an impact if hail injured the stalk (see Figure 1).

Bruising of Corn Stalk from Hail - June 2016 (Photo by P. de Rocquigny)

Figure 1: Bruising of Corn Stalks from Hail (Photo by P. de Rocquigny, June 2016)

The following information is adapted from articles “Recovery From Hail Damage to Young Corn” by R.L. Nielson of Purdue University and “Differentiating Superficial and Deeper Hail Damage” by C. Shapiro of Haskell Ag Lab.

Q: What will be the impact to yield? The eventual yield effects of severe bruising or damage of the stalk tissue itself can be quite difficult to predict. Consequently, it can be difficult to determine whether to count severely bruised plants in assessing plant stands. Observations reported from an Ohio on-farm study suggest that bruising from hail early in the season does NOT typically result in increased stalk lodging or stalk rot development later in the season.

Early season bruising of stem tissue may, however, have other consequences on subsequent plant development; the occurrences of which are hard to predict. If the plant tissue bruising extends as deep as the plant’s growing point, that important meristematic area may die; thus killing the main stalk and encouraging the development of tillers. If the plant tissue bruising extends into the area near, but not into, the growing point; subsequent plant development may be deformed in a fashion similar to any physical damage near the hormonally active growing point.

Q. How can I tell how badly damaged corn may be from bruising? Bruising is difficult to determine. You can make an initial assessment about a week to 10 days after the storm. Peel the sheaths away from the stalk and determine if the damage has actually penetrated the stalk. The outer stalk (rind) is strong and can resist some damage. However, if the stalk has brown areas, that may indicate stand problems later in the season.

Cutting the stalk vertically from node to node will help determine the extent of damage (Figure 2). Brown areas in the pith where the hail hit indicate the potential for problems later in the season. The stalk in Figure 2 does not show any bruising from the pith. These areas will disrupt the movement of fluids in the plant and reduce growth. Bruised plants that show stalk damage in the pith should probably be considered as missing plants in yield calculations.

Split corn stalk

Figure 2. Cut the corn stalk vertically from node to node to help determine the extent of damage. Source: Differentiating Superficial and Deeper Hail Damage

 

Remember that estimating yield loss due to hail is only an estimate, particularly if the damage is not severe and depending upon growth stage of the plant when the hail event occurred.  The remainder of the growing season will help determine final yields.  Please contact your hail insurance provider for their procedures in assessing hail damage as they may be different that what has been provided here.

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

Manitoba Agriculture website: www.manitoba.ca/agriculture
Manitoba Agriculture on Twitter: @MBGovAg
Manitoba Agriculture on YouTube: www.youtube.com/ManitobaAgriculture

 

Respond
Have a follow-up question?

Preplant Banding Ammonia & Urea in Corn

A very efficient placement method for rates of nitrogen that can’t be placed at seeding is the preplant band. Despite the popularity of direct or one-pass seeding this is still used in crops where some pre-plant tillage is done – like for corn.

The past few years, more often in dry springs, I have seen stand thinning using this practice. When the corn row falls directly over the N band (be it ammonia or urea), seedlings are injured, stunted and sometimes killed. This leaves a repeating pattern in an angle across the field.

There are some standard guidelines if using this practice:

  • Stand thinning may occur where the seed row intersects the N band. Band N on an angle so that it intersects just a short length of row.  OR if the injection placement can be controlled with accurate GPS guidance positioning technology, split with the future corn row.  Six inch separation should be sufficient.
  • Place the nitrogen deep. Banding at 3” depth may be sufficient for slot closure and N retention in the soil – but this will only be an inch or so below the seed. The original guideline calls for 4” vertical separation of injection point and seed.
  • The toxicity will be worse under dry conditions and on sandier soils.
  • Waiting a certain period of time offers only a slight increase in safety.  Injury can still occur even if planting is delayed for a considerable period of time.
  • Increasing plant populations to account for such thinning will not eliminate the appearance of gaps in the row.

Figure 1 is of corn thinning over a preplant urea band.

IMGP5778

Figure 1: Corn thinning over a preplant urea band (Photo by John Heard, Manitoba Agriculture)

Figure 2 is of corn seedling based on their proximity in intersecting the shallow placed preplant ammonia band.

IMGP1929

Figure 2: Impact of shallow placed preplant ammonia band on corn seedlings (Photo by John Heard, Manitoba Agriculture)

Submitted by: John Heard, Crop Nutrition Specialist, Manitoba Agriculture

Follow Manitoba Agriculture on:
Twitter: @MBGovAg
YouTube: www.youtube.com/ManitobaAgriculture

 

Respond
Have a follow-up question?

Safe Liquid Fertilizer Rates for Corn

Much of Manitoba’s corn receives liquid phosphorus as a starter in the seedrow.  But we cannot apply sufficient amounts with the seed to meet full crop removal (about 44 lb P2O5/ac for a 100 bu/ac crop).  The safe amount of seed placed fertilizer depends upon soil type, moisture, row spacing and seed furrow opening.  Ontario guidelines base the safe rates of fertilizer on N and K content of the starter fertilizer.  For 30 inch rows no more than 10 lb N/ac should be seedplaced – enough to provide 34 lb P2O5/ac of 10-34-0 liquid fertilizer or 8.5 US gal per acre.  But based on South Dakota  studies such rates could cause stand thinning of 4-9% depending on soil moisture and texture. Most farmers will not be pushing starter rates this high as they should have the bulk of their P needs met through a safer placement strategy.

More on these safe rates of fertilizer is posted on Manitoba Agriculture’s website at: http://www.gov.mb.ca/agriculture/crops/soil-fertility/print,safe-rates-of-seed-placed-phosphorus-for-manitoba–narrow-row-and-row-crops.html

Submitted by: John Heard, Crop Nutrition Specialist, Manitoba Agriculture

 

Respond
Have a follow-up question?

Safe Rates of Seed Placed Fertilizer – Cereals & Canola

A reminder that if seedbeds turn dry, the safety margin shrinks when applying seed placed fertilizer.  Seedburn can result from ammonia toxicity and/or salt content of fertilizers.

For nitrogen, our Soil Fertility Guide provided safe guidelines for seed placed urea on cereals and canola across a range of soil types and seed-fertilizer configurations.  With the increased popularity of narrow seed and fertilizer spreads with disk drills, the safe rates are reduced.  For example, safe urea rates for cereals vary from 10 to 25 lb N/ac going from sand to clay soil using disk openers on 6” row spacing.  These guidelines are for moist soil and should be reduced by 50% if seedbed moisture is lower when weather is hot and windy.

The safe rates of seed placed phosphorus depends on the crop, with cereals being quite tolerant compared to soybeans, dry beans and canola.  With a disk drill as described above, cereals can tolerate 50 to 60 lb P2O5/ac as mono ammonium phosphate while rates would be 20 lbs/ac for canola and less for beans.   If there greater seedbed utilization (i.e. narrower rows or a wider seedrow with less fertilizer concentration) rates could be more liberal.

More on these safe rates of fertilizer is posted on Manitoba Agriculture’s website at: http://www.gov.mb.ca/agriculture/crops/soil-fertility/print,safe-rates-of-seed-placed-phosphorus-for-manitoba–narrow-row-and-row-crops.html

Submitted by:  John Heard, Crop Nutrition Specialist, Manitoba Agriculture

Respond
Have a follow-up question?

Should I Plant my Corn Now, or Wait for Warmer Soils?

Is it better to plant into cold soils realizing the seed is going to sit there until the soil warms up? Or should corn be planted when soil temperatures are warmer and approaching 10°C?

Planting into cold soils.  Early planting is a component of successful corn production in Manitoba, to maximize yield, obtain high quality and low percent kernel moisture at harvest (which will decrease drying costs), and to ensure the crop is mature before fall frosts.

Cooler soil temperatures can delay the crop’s emergence. Wet conditions added to cold soil temperatures can favor soil pathogen development, increasing seedling disease risks in both germinating seeds and young seedlings. When planting early in the season or when the soil is cold, a planting rate 10% higher than the desired final stand should be considered to compensate for possible increased seedling mortality. As well, when planting into cool soils, other seeding management becomes important, such as good seedbed condition (good soil to seed contact) and planting operations (including planting depth).

For more complete information, visit Manitoba Corn Growers website at http://manitobacorn.ca/plant-corn-wait-warmer-soils/

 

Follow Manitoba Agriculture on:
Twitter: @MBGovAg
YouTube: www.youtube.com/ManitobaAgriculture

 

Respond
Have a follow-up question?

Qn: Where did all the weeds come from in that corn field?

Farmers are usually well advised to “control weeds early and often” in corn fields. Although many of today’s herbicide tolerant crops and herbicides can control weeds at almost any stage, it is early season competition that reduces nitrogen use efficiency. University of Wisconsin researchers compared weed free corn to delayed weed control. Spraying when weeds were 4” and 12” tall, required an additional 20-60 and 65-160 lb nitrogen /ac, respectively, to produce corn yields equal to weed free plots.

In our 2014 Crop Diagnostic School lesson, corn fertilized with 100 lb nitrogen/ac yielded 145 bu/ac with season-long weed control, 15 bu/ac less when spraying 4” tall weeds and 60 bu/ac less when spraying 12” tall weeds (Figure 1). Unsprayed corn yielded 9 bu/ac. Conversely, with no added nitrogen but early and consistent weed control, the corn yielded 95 bu/ac.

John Heard in corn field

Figure 1. Corn to left in background with full, but late, control of weeds suffered extreme nitrogen deficiency.

However, there are warranted exceptions to maintaining all growing vegetation from growing in corn fields. Many corn fields in southern Manitoba are currently seeded with a wheat or oat companion crop (see Figures 2 & 3). These fields tend to be at high risk of wind erosion: sandy textured, following potato or other low residue crops. Cereals seeded at or prior to corn can then establish and produce early season ground cover to minimize soil erosion and sand blasting injury to young corn seedlings.

Figure 2

Figure 2. A nurse crop of wheat emerging in mid-May, ahead of the corn crop in Winkler area.

oats in corn field

Figure 3. A nurse crop of oats emerging in late May, in Carman area corn crop, prior to spraying for removal.

For more information on erosion and cover crops visit MAFRD’s website at: http://www.gov.mb.ca/agriculture/environment/soil-management/soil-management-guide/soil-erosion.html

Answer Submitted by John Heard, Crop Nutrition Specialist, MAFRD

 

Respond
Have a follow-up question?

How to Determine Leaf Stage in Corn

Knowing what leaf stage your corn crop is at is extremely important since post emergent herbicides can only be applied to corn up to the label-specified leaf stage. Therefore both farmers and agronomists need to accurately stage corn plants. Herbicide labels often refer to plant height, crop growth stage (leaves or collars), or both when discussing corn growth stage limits for the application of postemergence herbicides. Below is a review of some common methods for determining growth stage. It is important to know which method the herbicide manufacturer is using to indicate correct herbicide application timing. For each method, the stage of the corn plant in Figure 1 will be determined.

Corn Plant Staging

Figure 1: Corn Plant Staging

 

Corn Height Method.  To determine corn plant height, measure from the soil surface to the highest point of the arch of the uppermost leaf whose tip is pointing down.  Don’t measure to the “highest point” on the plant, which is often the tip of the next emerging leaf above.  Refer to Figure 1 on how to correctly determine the height of a corn plant.

Both environmental and management conditions can have a great impact on the height of a corn plant. In cool, wet springs, corn often grows more slowly from a height standpoint but it is still advancing physiologically. A delayed seeding date, differences in tillage, and differences in soil type can also have a pronounced effect on plant height but relatively little effect on the stage of vegetative development. Hybrid can also have an effect on plant height as shorter-season hybrids tend to produce shorter plants. Because corn height varies a great deal due to growing and crop management conditions, it is not the most accurate way to stage corn plants.

Leaf Over Method.  The leaf over method is a common way of measuring leaf number. The leaf over method counts the number of leaves, starting from the lowest one (the coleoptile leaf which has a rounded tip) up to the last leaf that is arched over (tip is pointing down). Do not count leaves younger (inside) than this one, even though they are present in the whorl. In Figure 1, the corn plant would be at the 4 leaf stage.

Leaf Collar Method (V-stage).  The leaf collar method is generally the easiest to use. It also relates better to the physiological stage of the plant and thus to the effects of herbicides. Staging by the leaf collar method is done by counting the number of leaves with visible collars, beginning with the lowermost, short, rounded-tip true leaf and ending with the uppermost leaf with a visible leaf collar . Collars are not visible until the leaves are developed enough to emerge from the whorl. In Figure 1, the corn plant would be at 3 leaf stage (V3).

Staging Corn with Severe Leaf Damage.  Dead leaf tissue will not resurrect itself and will eventually slough off as the plants continue to grow. The question is whether the leaf stage of a recovered plant begins anew with the healthy leaves or whether the dead leaves (which may no longer be visible) should be counted. In other words, should a 3-leaf plant that has lost 2 leaves to frost injury now be considered a 1-leaf plant?

The simple answer is: If corn was a 3-leaf plant prior to the frost, physiologically it still is a 3-leaf corn plant after the frost, no matter how many lower leaves are damaged, dead, or otherwise missing.

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD

For additional information on how a corn plant develops, please visit MAFRD’s website at http://www.gov.mb.ca/agriculture/crops/production/grain-corn/how-a-corn-plant-grows.html
For the Guide to Crop Protection:  http://www.gov.mb.ca/agriculture/crops/guides-and-publications/index.html#gfcp
Respond
Have a follow-up question?

Can recent cold temperatures & snow impact corn emergence?

Cold temperatures, combined with excessive rainfall in some areas and even snowfall, has created conditions not ideal for the germination and emergence of corn planted recently in Manitoba. Research has shown that temperatures at or below 10°C are most damaging to the germination and emergence process, especially if the cold temperatures persist long after planting.

What is Imbibitional Chilling Injury? Firstly, imbibition is the process by which seeds absorb water for the initiation of germination. In corn, kernels must absorb (imbibe) about 30 % of their weight in water before germination begins (by comparison, soybeans must imbibe about 50 % of their weight in water).

Imbibitional chilling injury may result when water colder than 10°C is imbibed, and effects can be particularly severe in situations where seeds were planted into cool soils (10°C or colder), combined with cold rain or melting snow after planting (the most critical time for imbibition is within 24 hours of planting). The absorption of cold water can disrupt the reorganization of cells during rehydration and can result in the loss of seed vigor or seed death.  Note: A cold, heavy rain after planting seems to increase the chances of imbibitional injury, probably because it overwhelms the ability of the soil to warm the water before it reaches the seed (Source: Joel Ransom, NDSU). 

Symptoms of imbibitional chilling injury include swollen kernels that swell but fail to exhibit further signs of germination or arrested growth of the radicle root and/or coleoptile following the initiation of the germination process.

Instances of non-imbibitional chilling injury following germination during the emergence process can also occur, often causing stunting or death of the seminal root system, deformed elongation of the mesocotyl (the so-called “corkscrew” symptom) and either delayed emergence or complete failure of emergence (i.e., leafing out underground). This type of chilling injury is more closely related to physical damage to the outer cell tissues that literally cause death of the plant part or inhibit further elongation of the affected area. Thus, chilling injury to only part of the circumference of the mesocotyl results in the “corkscrew” symptom as the undamaged sections of the mesocotyl continue to elongate.

The Result of Cold Injury? If germination is impacted, poor stands could result impacting yield potential.  Plants that also develop from injured seedlings may be stunted and develop more slowly than normal plants.  This can result in unevenness in the growth stages of plants within the field.

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD 

Respond
Have a follow-up question?