Agronomy Update: Impact of a Mild Winter, Nitrogen Considerations & Key Alfalfa Reminders

Outlook on the Heels of a Mild Winter

With the generally mild temperatures and relatively low snowfall this winter, what might we expect going into spring?

Diseases:  What does the mild winter suggest for disease potential in our crops this year? 

• Probably not much.  Most of our diseases are fungi, most of them overwinter as spores in the soil or on plant residue, and most of them are well adapted to cool or cold and wet or dry.  So, I would not expect much, if any, impact on disease pressure.
• For the soil borne seed and seedling diseases that attack both corn and soybeans (pythium, phytophthora, fusarium, and others):  These diseases generally prefer wet soils and low oxygen conditions.  Thus, soil compaction, resulting in low oxygen in the soil will favor these diseases.  Wet, especially saturated or near-saturated soils, favor these diseases. 
• Disease pressure is largely a result of weather.  In general, higher moisture's favor most of our diseases.
• Management strategy:  Same as always:  Don’t work soils and plant when they are too wet.  Scout normally for diseases.

Insects:  What does the mild winter suggest for insect potential in our crops this year? 

• Probably not much, with perhaps an exception or two
• Many insects overwinter here; many others “fly in” from the south.  For those that overwinter here, most are well adapted and can manage just fine in mild or very cold temperatures.  Corn borer overwinters as larva in corn stalks – I expect no impact of the weather on corn borer populations.  Corn rootworm overwinter as eggs – no impact on this population.  Seed and seedling insect feeders – wireworms, white grubs, seed corn maggots, Asiatic garden beetle – no impact on these insects.  Stinkbugs overwinter as adults – the mild winter may have improved their overwintering survival, so we will need to keep an eye on this insect.  Flea beetle – this is one insect whose overwintering is improved significantly by warmer temperatures.  I would expect higher than normal infestation of flea beetle on seedling corn.  However, it is rarely, if ever, an issue in hybrid field corn (may be a problem in sweet corn or seed corn production).  Flea beetles are also capable of vectoring stewarts bacterial leaf blight in corn.  Bean leaf beetle overwintering is affected significantly by cold – given the warmer than normal winter, the potential exists for higher than normal bean leaf beetle numbers and increased potential for pod mottle virus in soybeans later in the growing season.
• Management strategy:  Same as always for insects.  Scout early and more intensively for flea beetle and bean leaf beetles, and later on for stink bugs.

Nitrogen Management Considerations

Nitrogen is one of the highest input costs yet one of the most important inputs in corn production. How nitrogen is managed can make or break a farm operation. There are many concepts and ideas on managing nitrogen. Frankly, I think some have made managing nitrogen too complicated. The constant fluidity of nitrogen availability is based on many factors and, the environment in the soil is critical.        

Soil microbes that regulate nitrogen availability are reliant on proper soil pH, temperature, moisture, oxygen levels and a food source (carbon and nitrogen). The bottom line is, that what is good for the crop is also good for microbes that regulate the availability of nitrogen made available to the crop.    

Since nitrogen is so highly controlled by the environment and costly, nitrogen applications should be applied as close as possible to when the crop will need it the most. Therefore, not over exposing the nitrogen to the environment any longer than necessary and risk nitrogen loss.          

Best Nitrogen Management Practices:

• Choose the right source of nitrogen for the timing and placement.
• Choose the right placement for the nitrogen source used.
• Choose the right timing for the source and placement.
• Choose the right rate of nitrogen.

The chart below demonstrates how various choices in nitrogen management may affect the results.

3 Year Nitrogen Study, Dairyland Seed Research Farm - Wabash, Indiana * (4 Reps)

*Corn Soybean Rotation.  Total 180#N each Treatment. No N Stabilizer used in this trial.  Take note of number of applications per treatment.

Please feel free to contact a member of the agronomy team if you have any questions or concerns, we will be glad to assist you.

Key Reminders for Planting Alfalfa

Plant Quality Seed: Plant the best alfalfa you can afford with great yields and disease package. Hint…contact your local Dairyland Seed dealer, District Sales Manager or Agronomist to help with this.

Soil pH: Alfalfa is described as the “Queen of Forages/Legumes”. Remember, most legumes prefer a soil pH of 6.8-7.0, and, in most instances, if you need to add lime or other soil amendments to correct this, it works best to do so a year in advance.

Soil Fertility: Alfalfa produces best with higher fertility levels.

• Phosphorous (P) soil test levels should be 15 ppm or higher. 20 ppm or more helps in higher yielding environments.
• Potassium (K) soil tests levels should be 200 ppm or more; 170 ppm is a minimum.
• Due to their mobile nature, Sulfur (S) and Boron (B) will more than likely need to be applied every year and should be correlated with a tissue sample/soil test and yield goals for proper rates.
• Nitrogen (N) lighter soils may need 10-20 units of Nitrogen in the seedling year. Prior to the alfalfa plants’ nodulation kicking in to supply the plants’ needs.

Seeding Depth: Alfalfa seeds need to be planted 1/4- to 1/2-inch deep with the sweet spot of 3/8 of an inch. Alfalfa has to have good to excellent seed-to-soil contact for stand establishment. Rule of thumb is that your footprint should not be more than 1/4 of an inch deep when stepping in worked soil. A Brillion packer does a great job of firming up the soil and, in many instances, this is done prior to and after seeding.

Soil Temperature: Alfalfa can start to germinate with soil temperatures of 40°F or more.

Seeding Rate: 15-22 lbs. for a direct seeding and 12-18 lbs. with a companion crop.

Check herbicide history for carryover: Prior to seeding, check your herbicide use history for the last two growing seasons on the intended field to be planted. Certain herbicide residue can reduce plants stands or kill alfalfa seedlings.

For information about alfalfa stand assessments coming out of winter, please see the March 24, 2020, newsletter here:

https://www.dairylandseed.com/about-us/news/agronomy-update-kicking-off-our-2020-agronomy-updates/

Corteva Technology Use Agreements

All growers with orders for any Corteva Agriscience brand seed product, regardless of crop or trait (including non-GM products) need to have a signed Corteva Technology Use Agreement in place by September 1. Growers should sign the Corteva Technology Use Agreement electronically at www.agcelerate.com. Signing electronically is preferable, however, paper copies are available at www.traitstewardship.com.

Brian Weller Western Region 507.456.3034	Dan Ritter Central Region 219.863.0583	Branden Furseth Northern Region 608.513.4265	Rod King Eastern Region 574.596.6721	Terry Jones Eastern Region 419.630.3115

enjoying our Agronomy Updates?  suggestions for topics you'd like us to weigh in on?  Drop us an email at dairylandseed@dairylandseed.com.  We'd love to hear from you!