Agronomy Tips: Are My Soybeans Healthy?

Are my Soybeans healthy?

By Maizex Agronomy Team

We have reached the stage in soybean development when nodules are forming.  Every year I customers that are concerned that their soybeans are yellowing.  We received a nice rain in most areas and warm temperatures have boosted crop growth.  In just a few days things have changed.  Soybean plants have used up the native nitrogen in the soil and they are in the transition phase where the nodules can fix atmospheric nitrogen to supply the plants’ needs.  In about 7 days these fields will be a healthy green colour.  We are seeing the early planted fields progressing very well and greening up nicely.  Dig up a few plants and look at the nodule development; if you cut a nodule in half, you should see healthy pinkish color tissue in the center of the nodule.

“Soybeans often go through a period when leaves are light green or even pale yellow. This is the period just before the nodules start to supply adequate nitrogen to the leaves and is an important phase in the development of a healthy crop. Once the nodules have established and start providing nitrogen, the leaves will turn a dark-green colour. If proper nodulation, sufficient nutrients and moisture are present, soybeans will remain yellow for only 7-10 days” (Publication 811 Agronomy Guide).

Why do some fields look worse than others or even within the same field where there are different varieties?  Different varieties display different characteristics.  Varieties that are great emergers and are very vigorous will show these symptoms before a slower, weaker variety.  There are even areas in the field that may have a little more compaction, especially from the heavy rainfalls last season. These areas are also showing these symptoms but may be showing them a little longer than loamy soils.

Be patient.  Get caught up on your paperwork and weed control, and let Mother Nature take over. For more information on nodulation, click here.  As always, if you have any questions, please contact your local Maizex Seed Specialist.

Chuck Belanger, Maizex Seeds Yield Specialist, North Essex and South Chatham-Kent Counties
Twitter: @sprayman63

Soybean Fungicide Timing

As you can see from the chart, economic return on fields with no disease is questionable. It does appear that earlier application timing may be necessary to maximize yield response. More trials are being conducted in 2014 (chart provided by Horst Bohner).

What is the correct timing for Foliar Fungicides to Soybeans?

Many trials have been conducted in Ontario both privately and publicly to assess the yield and quality benefits. Averaged across 5 years of trials, the average response has been an increase of 2.3 bu/ac over untreated beans. Seed size and quality can be improved, especially when there is significant disease pressure. In 2012, Dr. Dave Hooker (University of Guelph, Ridgetown) conducted trials to evaluate the correct timing for maximum economic return. The trial results showed that soybeans responded more when sprayed relatively early. An application at the R2.5 growth stage (full flower) provided more yield than at later growth stages (see chart). This research also correlates well with work done by the crop protection companies. Do not forget to use a minimum water volume of 10 gallons per acre (100 L/ha) to ensure good coverage.

Tim Welbanks, CCA-ON, CCSCP, Maizex Seeds Agronomy Lead
Twitter: @TimWelbanks

Corn – Important Growth Stage Milestones

Understanding what goes on within a corn plant is important to your final yield.  In order to track your corn’s growth progress, we use a standard Developmental Stage Key.  The Vegetative Stage of corn is noted by the letter V. As each leaf unfurls from the whorl, a collar is formed.   These collars are numbered 1, 2, 3, 4, 5, etc.  V6 corn might have 7-9 leaves depending on how you count and how fast the corn is growing - hence the reason to reference collars.  There are 3 main segments to the V staging that are critical in determining what your corn yield will be:
V5 – the number of potential ear shoots is determined.
V6-V8 – the number of potential kernel rows are determined.
V8-V15 (approx.) – the number of potential kernels per row is determined.

Stress, both environmental or farmer inflicted, can cause catastrophic results.  For example, drought stress or an application of herbicide at V7 (approx. 8-9 leaf) that the crop cannot tolerate could cause a reduction in kernel rows.  If the corn moved into V8 before the stress was removed, reduction of the number of kernels per row could also occur.  Reducing 2 kernel rows and 10 kernels in length means a 6.7 bu/ac loss (2 kernel rows x 10 kernels in length x 32000 plants/ac ÷ 95000 kernels/bu).

A great tracking tool that I use can be found here.  Register your fields and track your activities with the corresponding growth milestones!

Kirk Van Will, CCA-ON, Maizex Seeds Yield Specialist, West Middlesex & Lambton Counties
 

For more information on Maizex Seeds visit http://www.maizex.com

For video agronomy tips visit Farms.com Corn Report at http://www.farms.com/corn-report/

Source: Maizex