Wednesday, June 16, 2010

Retarded Beans? Retarded Drills?

Have you seen soybean fields this year that look like this one?  I have, more than once.  Fields of drilled soybeans with good rows beside blank rows.  Seen mostly on conventional tillage, but also on a few reduced tillage fields.  You would swear the drill was starting to run empty.  
What happened?  There is only one answer.  Inconsistent seed depth placement between the seed openers on the drill.  I have not seen this same problem on any field planted with a row unit planter.  Conventional tilled loam and silt loam soils were tricky this spring.  They were extremely mellow and soft, mostly because these soils dried early and had no pounding spring rains to settle them down.  It was easy to get soybeans planted too deep and the drill was an enemy.  It is a real pain in the rear checking seed depth placement behind a drill. 
1.Depth placement is not consistent within the row.
2.Many of us do not have the patience to check every row.
3.Where in the field do you check? 
If you happened to check on a firm headland and thought things were fine, you would be badly fooled in the soft soil off the headland.  In fact, it was a year to pack the soil in front of the drill, not behind it.
Curtis Gartly and Ron Murrell sent me the following photos of soybeans that were planted too deep.  The field looked like the one above.  The customer referred to them as "retarded beans".

I have been in the agronomy arena for many years and 95% of corn emergence and growth problems are created by planting corn too shallow.  With soybeans, there is a much higher probability that the problem is caused by  planting too deep.  We can get away with planting corn 3'" deep in loamy seed beds and not be hurt.  BUT, we cannot get away with planting soybeans 3" deep.  They break their backs and fold up like an accordion.  Pioneer rates all of their varieties by length of hypocotyl.  The hypocotyl is what you see in the picture on the shovel.  It is the part of the bean that pushes the seed up through the soil.  Some varieties have longer hypocotyls than others.
These are the hypocotyl ratings of Pioneer varieties grown in this area.

90M40      Long
91M01      Medium
91Y20       Long
91M41      Short
91Y80       Long
91Y90       Medium

In other words, if you plant 91M41's you need to pay very close attention to seed depth.  90M40's on the other hand are a little more forgiving.  But no soybean variety emerges well from 3" deep.
Fortunately, soybeans do not penalize badly for weak stands and some folks will continue their sloppy practices.
Retarded beans?  Retarded drills?  An agronomist I know referred to drills once as "controlled spill devices".  He was exactly right. 


Tuesday, June 15, 2010

Are your beans yellow?

The most commonly asked question over the last week is "Why are my soybeans yellow? They looked fine the week before".  The first part of the answer to this question is quite simple.  Up until the soybean plant starts to initiate tri-foliates, it uses the reserves of the cotyledons for energy to supplement its needs.  Now those cotyledons are dried up, as in the picture below, and the plant has to get all its nutrition from it's root system.  The roots aren't quite ready to take the full load, so the plant turns yellow.

This yellow condition should only last a few days and if your beans turn dark in a week, there usually is not a big yield impact.  Some people would argue that this stress of losing the cotyledons is necessary for the rhozobia bacteria to start colonizing the roots and making nitrogen.
The second part of the answer to why beans turn yellow is more complicated.  Look closely at the picture below of a stand of soybeans planted the same day, same drill and same variety.

The left side of the picture is wheat stubble, fall chiseled, spring cultivated.  The right side is corn stubble, no fall tillage, 2 passes with a Salford RTS during the last week of April.  Why no yellow beans in the wheat stubble?  Their cotyledons have dried up the same as the beans in the corn stubble. The picture below is of two plants taken from this field.  The plant on the left is bigger with one more tri-foliate.  The nodulation on each plant is about the same.  Why the growth difference?

If we had to put it down to one thing it would be soil temperature.  The soil on the left is warmer because it has less residue covering the surface.  A 170 bushel corn crop leaves a lot of residue and keeps soils in place through the winter. But it also keeps soil from warming in the spring.  The extra tillage following wheat also leaves more air in the soil, which helps it warm quicker.  Will this have a yield impact?  We do know it won't be as great a difference as you may think, but we will let you know.   

Friday, June 11, 2010

My Neighbours Have Some Nice Crops

The growing season to date has been pretty good in the St Marys area, unless you are trying to make dry hay.  It does need to stop raining to allow field work to catch up and Cathy's gardening keeps getting interupted.  More rain forecasted for the weekend.  In the meantime, check out these stands from the area.  This Pioneer corn is good stuff.

These soybeans don't look too bad as well.

Tuesday, June 8, 2010

Are we smarter?

Dennis Berglund, a crop consultant from Minnesota recently reported on a weed survey conducted by University of Minnesota and North Dakota State University extension specialists.  They surveyed fields in Minnesota and eastern North Dakota.  In 10-40% of all fields they identified some form of glyphosate resistance within the weed spectrum that was present in these fields.

The three weeds most often identified were common ragweed, giant ragweed and waterhemp.

Common Ragweed
The lowest area had 10-30% of the fields with resistance, in the mid-Red River Valley
The highest area had 30-60% of the fields with resistance, in central MN
Giant Ragweed

30-95% of the fields showed resistance, in south-central MN
Waterhemp (a member of the pigweed family)
5-20% of the fields showed resistance near the corner of ND, SD and MN.
Scary numbers caused by
1. high concentration of RR crops
2. over reliance of glyphosate alone for weed control
In Ontario we have been through similar situations before. 
Triazine resistant lambsquarter and pigweed exploded in the 70's because we grew too much continuous corn and relied on atrazine for weed control. 
Group 2 resistant foxtail, ragweed, lambsquarter, pigweed, waterhemp and others showed up in the last decade where we relied too much on group 2 products such as Pursuit and Accent.  
Interestingly, atrazine and Pursuit are still effective herbicides when combined with other products, so all is not lost.  I think the Ontario farmer is smart enough to realize the way to keep glyphosate as an effective herbicide is to rotate crops and tank mix other herbicides with glyphosate to keep resistance from developing.
On the other hand we do have confirmed glyphosate resistant giant ragweed in Essex County. 
And a few growers are still lulled into thinking that glyphosate alone will solve all their troubles like the one below that Brian was asked to spray recently.

And I still hear too many of my chemical retailer friends talking about customers coming in after the crop is emerged with no herbicide applied, looking for the one cheap fix to take care of all their weeds.  We can do better.

Wednesday, June 2, 2010

A Return to"Beans Beans"

On Thursday May 6, I published a photo of an emerging soybean field.  I have had some requests for an update to the status of this field, given how the frost on Monday May 10 was so widespread and damaging to the emerged corn crop.  Farmers would generally agree those beans should be toast. 
Here is the same picture from May 6.

Here are the same plants on May 17, one week after the frost.  Looks like the top two would live, but the growing point between the cotelydons on the bottom plant looks badly wounded.

The next shot was taken on May 24, two weeks after the frost.  Plants are alive, but not growing quite like a normal soybean.  A normal soybean produces two single leaves before it starts producing tri-foliate leaves.  The single leaves are missing and it is straining to produce tri-foliates.  We also see more branching, elongated stems and cupped leaves.  New growth is appearing from the auxiliary buds at the base of the cotelydon.  It is truly amazing to see such small plants fight for survival. 

On May 31, we see plants that look like the one below.  Older leaves are beat up and wrinkled, but the plant is growing.  The newest tri-foliates are looking normal.


This is a picture of the whole field.

Six random stand counts revealed a surviving plant population of 123,000 to 180,000 plants per acre, with the average of the six counts at 151,000 plants. The field is definitely a keeper and a vivid demonstration of the toughness of a soybean plant.

As a further follow up, I compared the April soybeans to some of our own planted on May 19, exactly one month later.  The April beans on the left have begun to form nodules.

We will continue to monitor the differences.