Agronomy Zone 4

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• Jeff Anderson (12)
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• Todd Schomburg (6)
• Doug Score (2)
• Stine Seed (21)
• Trevor Stockstad (3)
• Louis Sutton (18)
• Kenneth Wolf (3)

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Every year there is an outbreak of Green Stem Syndrome (GSS) somewhere in the United States. Many people think it is a varietal problem, when it really is not. 

There are two major causes of GSS. The first is a virus with the Stink Bug, the insect that causes GSS.  Treating for this is rarely beneficial due to the fact that normally the damage is done before the Stink bug is found.  The main cause of GSS is actually high stress during the reproductive stage of the soybean. Heat or drought stresses that cause the plant to abort pods allow the plant to build up too much sugar, starch or other nutrients. The nutrients are then put into the leaves and stems of the plant. With these extra nutrients it does not allow the plant to mature correctly. That is usually the leading cause of GSS.

Most farmers want to wait to harvest the fields with GSS, and unfortunately this just leads to lower yields due to shattering. The green stems are definitely harder to cut and work the combine more, but this is really a minor expense compared to the loss of bushels due to shattering because the soybeans are ready to cut and the soybeans keep losing weight from the loss of moisture in the seed. 

Agronomist Louis Sutton suggests growers add LibertyLink to their planting rotation to fight glyphosate resistance and protect the Roundup Ready technology.

In the Field with Louis Sutton - Southern Growers Switching to LibertyLink

In parts of Missouri we are finding some very confused corn in the fields lately. I have seen corn that is either not emerging correctly or, in some cases, not emerging at all. We have found cases of corn that is literally growing upside down, as the growing point is headed deeper into the soil and the roots are rising to the surface; in addition, seedling blights are attacking the seedlings. 

The reason for this unusual growth pattern is due to a cold, heavy rain followed by prolonged cold weather after planting. In this case, the rains cooled the soil above the seed to a colder temperature then the soil below. As a result the growing point, which tends to grow toward warmer temps, actually turned and went deeper, and alternately the roots started growing up toward the surface. As temparatures rebounded and soil temps normalized, then the plant tried to change the direction of growth. The picture above shows some example of corn seedlings with these malformed mesocotyls. In these situations, the mesocotyl will develop an S curve or sharp bend in it. If you look closely you can see the roots that started growing up and not down at the 45 degree angle that it should have. This is a very rare thing to happen, and (fortunately) most people will not ever see this.

Meanwhile, as all of this was happening, the cool wet soils allowed the seedling blights to attack the seed and plants. This has led to some replant situations. We are also seeing seeds sitting in cold soils and getting attacked before they could even germinate. 

One more thing, we also are seeing western bean leaf beetle adults already feeding on the volunteer soybeans, so an insecticide with your burn down spray could pay big returns for you this year.

The University of Illinois conducted research where corn was planted at a depth of 2 inches on a silt loam soil on top of NH3 injection bands. In this study, there were three NH3 injection depths (4, 7, and 10 inches), three dates of planting (0, 1, and 2 weeks after NH3 application), and two nitrogen (N) application rates (100 and 200 lb N/a). There was also a control treatment where no NH3 was applied.

The 100 lb N/a rate showed no reduction in stand compared to the control 27 days after planting for any injection depth or date of planting. The 200 lb N/a rate showed significant stand reduction at a 4-inch NH3 injection depth, but no stand reduction at the deeper depths when planted the day of NH3 injection.

Depth of injection more important than days

Plant height was slightly stunted 41 days after planting when 100 lb N/a was injected the same day as planting at a 4- or 7-inch depth; if injected at 10 inches there was no stunting apparent. While, the 200 lb N/a showed severe, slight, and no stunting for the 4, 7, and 10 inch NH3 injection depths, respectively.

Overall, depth of NH3 injection was more important in reducing injury than was the amount of time between NH3 application and planting.

Follow these guidelines to minimize corn injury

To prevent or minimize injury when planting corn a few hours after NH3 application, Lang advises farmers to: 

• Inject NH3 at least 7 inches deep and perhaps as deep as 10 inches if possible. 
• Do not plant the corn row directly on top of the injection bands. If possible, apply NH3 at an angle relative to the corn rows. 
• Lower N application rates will minimize risk of injury (e.g. typical N rates in corn-soybeans vs. corn-corn situations).
• Ensure that the soil closes behind the knife openings to limit N loss and movement upwards towards the seed.