Here's A Tip

Tip fill in corn is a debated topic that is filled with more emotion than fact.  As a producer I feel better when my corn crop is filled right to the tip.  It makes me think I have done everything possible to grow a strong crop with maximum yield potential.
And a well filled ear will win 1st prize at the local fair every time.

As an agronomist I have a different attitude because of my understanding how a corn plant works.  A less than perfect tip can be the result of several complicating factors that do not always compromise yield potential.

The number of kernels is set at silking time.  A healthy plant with adequate water and sunshine will fertilize the maximum number of kernels possible.

The tip silks are the last silks to emerge from the ear.  This picture shows tip silks that were not fertilized.
If the plant is under moisture stress it will abort the tip kernels.
If the plant is under severe heat stress, like we had the last week in July, kernel tip abortion can happen because pollen shed occurs too fast and tip silks emerge too slow.  When the tip silks finally emerge, pollen shed is finished.  This is known as missing "nick" in the seed corn production business.
If moisture stress occurs after silking the corn plant will decide to abort fertilized kernels at the tip in favour of saving kernels further down the ear.  This is a self preservation mechanism.

But all is not necessarily lost because genetics can play a major role.   Some hybrids don't have it in their gene pool to give a nice pretty tip.  They routinely will show a little "dirty nose".

Here are a couple of new hybrids, P9910XR and P9760HR, that may not have it in the family tree to fill their tips.  Does this make them inferior?  If you grow corn to win field crop competition at the fair, then the answer may be yes.  But, my experience has taught me that this style of hybrid can yield very well.

The reason is the corn hybrid doesn't care what it's tip looks like.  It carries on by can packing many rows of deep kernels around the cob.  The few tip kernels missing are more than made up for by deeper, heavier kernels lower down the ear.
They may not be the prettiest girls at the fair, but you should take them home anyway.

No Joy Indeed

In a post two weeks ago, I spoke about a field that we suspected to be infested with soybean cyst nematode.  I received the lab report yesterday from samples collected in this field.
Two different poor spots in the field were sampled.  The amount of cyst is reported in 100 gm of soil.

Poor sample #1        Soybean cyst   78
                                 Eggs          14820
Poor sample #2        Soybean cyst   86
                                 Eggs          17200

In the good areas of the field, the soybean cyst and egg numbers were not detectable.

The following chart from OMAFRA's Agronomy Guide outlines the risk level at various populations of eggs and soil types.
 

SCN Population #eggs per 100 grams of Soil	Risk Rating	Potential Yield loss	Rotation
0-500 coarse sand	low	0-20%	4 years
0-1000 Fine textured silt, clay	low	0-20%	4 years
1000 coarse sand	high	20 -50%	6 years
2000 fine textured silt clay	high	20 -50%	6 years
10,000 all soils	Resistant varieties may be damaged	----------	---------

You can see with levels of 14-17000 eggs per 100 gm of soil that our samples are extremely high.  This situation should not be taken lightly.  The field needs to be taken out of soybean production for a long time and when soybeans are grown again a cyst resistant variety will be absolutely necessary.
It certainly has served to be a wake up call that soybean cyst is in our backyard.  Joy!  

Immigrants!!!

When it comes to insects, Canadian Border Services are no help.  Bug trade with the US only goes one way, north.  Last month I showed pictures from some western bean cutworm traps.  There were significant adult moth flights through areas of the province, as demonstrated by this trap at Dresden.

The offspring of this flying menace are starting to show up.  The following two pictures came from a corn plot near Dashwood, courtesy Blair Freeman, Pioneer Area Agronomist.

 

Our local trap has not produced high adult counts, but these devils can make turn an ear of corn into a mess.  Any hybrid using only the  Monsanto YieldGard gene for insect protection is at risk.  Herculex hybrids offer significantly better protection against western bean cutworm.

One more reason to keep Pioneer hybrids in your line-up.

There Is No Joy

Sometimes it seems like agronomists take joy in finding crop pests.  I guess it proves they may actually know something.  I have never been one to get very excited when discovering a pest in a customer's field, particularly one that has a nasty reputation.  The latest villain to show its presence much too close to home is the soybean cyst nematode.

From the road the field looked like this, yellow patches surrounded by healthy plants.

In the patches the plants looked like this.

 

And this.





Digging up plants and washing roots exposes the culprit.

Plants infected with soybean cyst are typically stunted, yellowed and dying with decaying outer leaf margins.  The nematode invades the soybean root and produces a nodule that looks something like a rhizobia nitrogen fixing nodule, but is smaller and white in colour.  This nodule is the reproductive stage of the female nematode and is actually the egg sac.  When the female dies the egg sac or "cyst" breaks away.  The eggs inside the sac can survive for several years and emerge to infect a subsequent soybean crop.

 

Soybean cyst is estimated to be the number one yield limiting pest to soybean production in North America.  I have randomly sampled fields in our neighbourhood for cyst nematode over the last 3 years and found either no cyst present or extremely low levels of cyst.  This field has not been previously sampled.

Cyst spreads easily from field to field in the dirt that travels on machinery.

Cyst can be managed, but it requires discipline.  Fields need to be rotated to non-cyst crop hosts like corn and wheat.  The longer the rotation away from soybeans the better. 

There are resistant varieties to cyst, but we have two problems.

1.  There are not many choices of cyst resistance in varieties for our maturity.  Pioneer has one, 90M80, a 2700 heat unit RR variety.  Growers in the fuller season areas of Ontario have more options.

2.  There are only three sources of resistance for soybean breeders to work with.  Cyst nematode populations are composed of many races.  The population can quickly shift races in the field to overcome genetic resistance. 

No joy indeed.

Relax Fellows, Life Is Good

Customers have been asking what my badly dented crystal ball has to say about the corn planted in June. 
They are actually asking two questions.  Will my crop make maturity?  How will it yield?
The first question is easy, because the short answer is yes.  Corn planted in June responds by using less heat to get to tassel than corn planted in May.  It is a built in safety defense mechanism to save itself in shorter growing years.  Using local figures, May 10 corn needed about 1700 heat units to reach tassel and June corn reached tassel with about 1450 heat units.
The normal silking date for corn in our area is the last week in July through the first week in August, so the June corn is pretty much on schedule.
This is one June field that you can see was tasseling last week with silks beginning to emerge.

It has been a week since these pictures were taken, so pollination will be moving along quickly.

After pollination, corn advances through 5 stages of 12 days each, or a total of 60 days, to reach physiological maturity.

1-12. Milky embryo or blister stage

12-24. Young sweet corn stage

24-36. Beginning dent stage

36-48. Half milk line stage

48-60. Hard dent stage

Corn pollinating in early August will be frost hardy by early October. 

The average fall frost date for this part of Ontario is the first week in October.  Problem solved, June corn has an excellent chance to make maturity thanks to the warm June and July.

How will the June corn yield?  Today my crystal ball says very well.  But my crystal ball also predicts the May corn to be a bit better.  This is because early grain fill for May planted corn is done during longer daylight hours.  Yield is a function of turning sun energy into plant energy.  Daylight is a huge factor, along with moisture availablity and plant health.  Heat during grain fill is not as important as it is during early growth. 

Heat becomes more important in the drydown phase, but there will be time to talk about that later.

The Power of Technology

Morris Van De Walle e-mailed this picture to me this morning taken with his smart phone camera. 

He asked if I knew what it was.  I had no clue, but a quick search put me onto the following link.

http://bautebugblog.com/what-is-that-flea-beetle-in-soys-and-other-crops/

Time invested, 15 minutes.  If a grey beard like me can figure out how to do this stuff, anyone can.  

One Twenty Seven Point Eight

I walked through Brian's wheat plot 2 weeks ago and thought "Wow, there is a lot of wheat here".  My thinking was it would make 110 bu easy, maybe 120 bu if I put on some rosy glasses.  I was wrong.  We took it off yesterday and here are the results.

Pioneer      25R56      14.6%     127.8 bu/acre
Hyland      Branson    14.2%     118.0 bu/acre
Pioneer      25R40      14.4%     123.1 bu/acre

This plot was planted on October 9.
N rate - 120 lbs as 28%
Herbicide - Buctril M
Fungicides - Stratego with the Buctril
                  - Prosaro at heading

25R40 is a new variety from Pioneer that is shorter in height, much like 25R47.  This means we may be able to push it even higher with additional management like increased seeding rates, extra N and fungicides.