Plant Stand assessment – improved accuracy with measuring wheel.

If you have ever been frustrated trying to get an accurate plant population for an emergence issue using 1/1000th of an acre count there is a better method. For the last few years I have been using the measuring wheel method and have more confidence in my plant stands. The benefits of using this method are reduced ‘cherry picking’ of visually good or bad areas of the field, speed of count and improved accuracy of the count.

How does it work?

To use this method of population counts you push the measuring wheel and count 150 plants (I count by two’s, if you are really good you can count by three’s). When you reach a count of 150 plants, record the distance traveled in feet. Sorry no metric here record the measurement in feet. Repeat the count/measure three or four more times in the field or affected area. Average the measurement and convert using the following table by dividing the average number of feet for 150 plant count into the conversion factor. Example if I averaged 100 feet in a 30 inch row spacing the population would be 26,613 plants per acre (ppa) (2,613,600 divided by 100 feet = 26,136 ppa).

Also, assess non-emerged seedlings using the checklist in the Replant corn – How to decide article, by recording the population and the emergence issues we can make a good agronomic decisions for this year and future years.

Replant corn – How to decide.

This year we had some fields that were planted early and then went thorugh a very wet, cold period and now the emergence is less than desirable in some areas of the field. Do I replant the poor sections, or the whole field (with the price of corn this would be a very costly option), do I leave it alone, these are all very good questions.

Corn replant decisions are difficult. The following table can be utilized as a guideline when assessing yield potential at various planting dates and populations. In general it doesn’t pay to replant corn where populations of healthy plants are greater than 18,000 plants per acre
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First we need to establish the population that has emerged. You can do this by counting the number of plants in 1/1000 of an acre (see chart). Do this a number of times in the field. Also, assess the cause of reduced emergence using the following checklist.

 Rotted seed or seedlings
 Sprout twisted or leaves expanded underground
 Seeds hollowed out (insect damage)
 Check seed intactness (firmness)
 If seed is watery or “yellowy pus” it is not going to emerge
 Do not worry about crooks or turns of the coleoptile (shoot) as it may be responding to the seed orientation (corn seed does have an up and down side); also, cold soil will often disorient coleoptile growth.

As this is a very difficult decision please contact your NK field representative or seed dealer if you have any questions.

It’s time to switch

I have finally pulled the trigger and it is time to switch in all the Ontario corn growing area’s except maybe Essex County to a hybrid that is 100 – 150 CHU less than your normal maturity that you would plant. With the recent wet weather please work with your corn supplier to get the required seed to your farm. Be aware as this may take a couple of days as we are moving seed all over Quebec and Ontario to make sure you have the best seed option for your farm and situation.

Is it time to drop corn and switch to soybeans? This depends on each individual situation but you need to think about the following:
1) Do I have enough corn at 75% of expected yield to meet your delivery contracts this fall?
2) Do you need the production for feed?
3) Is the current fall delivery price worth the risk of reduced yields?
4) Herbicide or fertilizer is applied for Corn?
5) Do not want to risk changing my rotation?

Do you have other reasons to continue to plant corn, please include in the comments.

Late planted Corn

In Ontario and Quebec in 2011 we will have the majority of the corn planted after the optimum date of May 10th. What does this mean and what should our expectations be?

At the time of writing this (May 18th) it appeared we would be at least a couple of days before we could be back planting. Should we switch hybrids? I would recommend in the shorter growing season areas (<2750 CHU) switching now (drop 100 CHU per week delay but do not go below a 2600 CHU hybrid) and for mid range (2800 – 3000 CHU) switch around May 25th and rest of the area's do not switch until June. (reference: Switching to Earlier Hybrids).

What should we expect for yield this fall due to the delayed planting conditions this spring? First remember many other factors still affect yield other than planting date such as fertility, population, hybrid selection, weather, seed depth, compaction, etc…

Yield : expect to lose one bushel per day delay from May 10th or around 10% if delayed until June.

Harvest Moisture: On average expect one point of moisture increase for every four days delayed from May 10th. If delayed to early June a five point increase or 30% moisture compared to 25% if planted early.

Test Weight: Long term average is one pound of test weight loss for every 10 days delay in planting or 2 lbs if delayed to early June.

What can we expect if delayed to early June? 20 bu per acre ($100.00 per acre) plus on an expected 150 bu/ac crop $0.20/bu drying cost increase (assumed drying $0.04 per point per bu) equals $26.00 per acre. Assuming we do not lose grade due to reduced bushel weight a delay until early June could end up costing $126.00 per acre at $5.00 per bushel corn.

Let’s hope for a break in the weather and get this corn crop into the ground.

Planting Effective Plots

Quality data can only be achieved through quality plots. Establishment of the plot is critical we need to be aware of the following things:

Pre plant preparation

• Stakes, forms, GPS unit, safety equip.
• Check plot seed inventory – do you have the hybrids you want
• Plan ahead– If possible plant the plot early in the season.

Successful Plot establishment

• Site is level and of one soil type
• Watch for dead furrows
• Identifications stakes – 2 per variety in the corn row
• Documentation – fully completed (includes soil type, tillage, previous crop etc.)
• GPS location or map to find site
• Correct planting depth
• Population – watch seed size and changes in population
• Leave documentation with dealer or NK rep.

In season Assessment

Monitor that the stakes are correct
Trim fronts or make a path to and along the front of the plot for easier access.

Assessments

• Spring Vigour
• Flowering/pollination
• Pest pressure – insect/weed/disease
• Maturity – milk line or black layer

Harvest assessment

• Population
• Lodging
• Pest pressure – insect/weed/disease
• Stalk integrity – push test
• Moisture
• Test weight
• Yield

Remember using your plot information and information of other plots in the area and throughout North America as the best way to get the ‘right hybrid on the right field for the highest yield’.

Is it better in the bag or in the field?

It is hard to be patient at this time of year. We all know that the sooner we can get started planted the better or is it? Yes and only if the conditions are right for quick emergence is this true. It takes approximately 100 – 150 CHU to emerge corn and with the daytime temperatures to date we have accumulated nothing in the way of heat units. If you have corn planted you are playing the waiting game to see when (if?) it is going to emerge. With our current genetics, quality standards and seed treatments seed can survive delayed emergence significantly better than 10 – 15 years ago, but if three to four weeks go by and we still have not seen the corn it will be hard to be patient and wish that you left it in the bag. So what should you do? Plant as soon as the soil is fit.

Should I start changing my hybrids to lower heat units? No. Prior to May 10, Syngenta Agronomy Research shows only a one bushel (or 0.11 bu/day) of corn yield loss with a ten day delay in planting. If you did not get finished planting until May 7th this year compared to April 28th last your expected yield loss is one bushel per acre. What about after May 10th? You may want to consider switching your very long heat unit corn to a shorter day hybrid and plant the rest. Our research has shown a one bushel per day for every day of delayed planting. What about May 24th? This topic will be discussed if delay occurs.

In the meantime we need to practice patience. Our elders were correct – patience is a virtue.

Corn planting tip – Watch maturities

It is a funny time of year to discuss corn maturity but as we make our final plans for spring it is important that we realize the factors that go into assessing corn maturity and the difference between physiological maturity and dry-down. Corn maturity starts after pollination and is complete at physiological maturity (black layer). Imagine the kernel as a glass and at pollination the glass is full of water. For the next 55 – 60 days we keep adding pebbles (starch and protein) to the glass (kernel) displacing water till the kernel is full. When the kernel is full of starch and protein and the maximum amount of water is displaced (there is still water between the pebbles (starch)). The kernel then full forms a layer of cells (bottom of the kernel) that turn black/brown forming what is called the black layer. The moisture of the kernel at this point is approximately 28 – 35 %.
What factors affect the rate of water displacement in the kernel?– Heat and sunlight
– Insects and disease – European corn borer, stalk rots, crown rots, rust
– Frost
– Cold weather – 4 to 5 days where maximum temperature does not exceed 130 C.
How do we get the rest of the water out of the kernel? Evaporation. The measure of moisture at harvest is a measure of dry down or the rate of evaporation of the remaining water from the kernel. Factors affecting the evaporation are: Thickness of pericarp (thin skin on the kernel), Kernel type (flint vs. dent), starch density (bu. weight) environmental (humidity), husk type/amount and ear orientation (by hanging down the ear sheds rain/dew accumulation)
How do we assess corn maturity?
Many factors are considered such as flowering (pollination) date to black layer formation and dry down. The most important is black layer compared to similar maturing products. Moisture is used to predict maturity but is more relevant when the harvest moisture is over 28 % moisture.
Taking it to the field A excellent corn year, such as 2010, often will skew corn maturities. It is important to not get caught planting too many late day varieties the following year. Maximum yield is produced with early planting dates for all the corn hybrid maturity groups (short, mid and full season). However, the yield reduction with delayed planting is the greatest with the full season hybrids compared to earlier maturing varieties.
At NK Brand we feel it is important to select a risk-free seed portfolio allowing you to manage the environmental risk of the growing season. By planting a 20:60:20 (short:mid:full season) maturity portfolio manages risk. When planting this type of portfolio, plant the full season varieties first, then the mid season and lastly the short season varieties. For maximum corn yield, all groups of hybrids should be planted as early as possible. Full season variety selection should include varieties that exhibit early flower and fast dry down traits. It is also important to have a late planted short season variety with the same characteristics.
Work with your seed specialist or NK Brand representative to build your corn portfolio.

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