Agronomy Update: Fall Burndown, Tillage Conditions & Interpreting Yield Data

NOW IS THE TIME TO APPLY HERBICIDES FOR FALL BURNDOWN!

Fall burndown applications will enhance your weed control for the control of winter annuals, dandelion, perennial weeds and marestail (aka horseweed) for no-till corn and soybeans. Fall burndown treatments are most effective from early October to mid to late November. However, fall burndown will remain effective later if weeds are still green and not killed by a freeze. Keep in mind, weeds will die much slower with cooler temperatures. 2,4-D and Dicamba are less affected than Glyphosate with cooler temperatures and cloudy weather.

For those with stubborn marestail populations, fall germinated marestail start stem elongation much early then spring germinated marestail and are more difficult to control in the spring. Eliminating winter annuals in the fall will not only help with starting next spring cleaner, but will eliminate potential egg laying sites for Black Cutworm, Armyworm and host sites for Soybean Cyst Nematode.

Even if a fall herbicide is applied, it is important to apply another burndown and apply a residual herbicide in the spring. Then follow up, if needed, with a post herbicide.

Many times, a fall applied residual herbicide does not appear to perform better than a fall applied 2,4-D, Dicamba or Glyphosate alone or in combination. It’s probably more economical to save the residual herbicides for spring, where it is needed most and get more bang for the buck. Besides, some fall applied residuals may restrict you next spring with crop choice if you need to change plans.

For tough or hard to control weeds it is important to be relentless and take every opportunity to manage.  Fall treatments are a very important tool in managing weed control concerns.  As always, read and follow the label on products you select and understand any restrictions for planting intentions next spring.

FALL TILLAGE CONDITIONS

Let’s be clear: tillage destroys soil structure. We all know that tillage can loosen poor soil structure and compaction, but it doesn’t really create good soil structure. Good soil structure is formed by the presence of roots and other soil organisms, without disturbance, over extended periods of time. Think about that crumbly soil under long-time CRP, an old hay field, or on farms that are finding success with no-till and cover crop systems. For the most part, poor soil structure is formed by human disturbance. There could even be an all-around lack of soil structure. In these cases, the soil is concrete hard on the surface and is powdery when worked. In a year where you are probably testing the limits of what you should do, what should you watch for?

Too wet: If standing water in the field doesn’t give it away, soil will “ribbon” when squeezed in your hand. Tillage clods are large and the surface of the clods will have a smeared look. These large clods will lock up as they dry and be difficult to break in the future. It’s like a good sear on a steak that locks in the flavor, only we don’t plan to eat these soil clods. This issue could lead to lumpy soil that makes for poor seed to soil contact for many planting seasons to come.

• If you must till: Ask yourself if you really need to be out there… then ask yourself again. Keep it shallow; this probably isn’t the time to break a plow pan, but filling in ruts and light residue incorporation could be possible.

Too dry: Soil will “shatter” with tillage, even in areas with little compaction. The edges of the clods will often appear sharp and ridged. Tillage in dry conditions can pulverize any existing structure and further release needed soil moisture.

• If you must till: play the soil moisture conservation game. Favor more residue on the surface with strategies such as shallower tillage, straight chisel shanks or slower tillage speeds. Or wait until spring altogether.

Just right: Soil will be crumbly off the tillage implement and in your hand. The natural fracture lines of the soil clods will be visible. These are “green light” conditions. Realize that if soil compaction is not root limiting, you are probably just burning more fuel than necessary and creating a risk for more compaction. Of course, things like residue management and manure incorporation are also factors.

INTERPRETING YIELD DATA OF SEED PRODUCTS

This is an exciting time of the year with combines rolling across the Midwest. As we evaluate everything from fertility to seed decisions, it’s fun to see the rewards of good planning and execution in the field. Sorting through the yield data on corn and soybean varieties quickly becomes overwhelming with the barrage of data. Extensive testing networks, both public and private, release results on a daily basis, while we make our own first-hand observations. Hopefully you too have included new seed products on your acres to assist your 2021 decision-making process. Here are some things to ponder as you digest seed data and plan for the future. Remember, help is just a phone call away!

• Balance your analysis with local and regional results. Seek data from environments that are similar to your target environment. There might be something to learn, even if data is not within your exact geography.
• Consistency should be a high priority, possibly more than pure yield. It’s nice to study trial winners, but look for those products which are consistently in the top 1/3, and you won’t be let down. Does your ball club want the player that wins the homerun title one year? Or the career .300 batter hitting all singles and doubles? Of course, a consistent homerun hitter would be nice, but that’s more like a unicorn.
• Find benchmark or check varieties that are entered in many trials to help draw conclusions across testing programs or locations.
• If looking at strip trial results, pay attention to the number of repetitions and also realize that data may not be balanced. Look beyond the average yield data. If Product X averaged 250bu and Product Y averaged 230bu, were they at the same locations? If so, the data is balanced. If not, was one of them planted on more stressed locations than the other? Calculate how each performed as a percentage of the trial mean to cut through this.
• Consider (maturity or moisture) in your evaluations: later maturing varieties bring more yield, so a plot winner may not be as impressive if its 3 points wetter than average at harvest. Compare products of similar maturity
• Small-plot statistics lingo
• Coefficient of Variance (CV): calculated as the ratio of standard deviation: trial mean. Standard deviation is a measure of the dispersion of data points around the mean. Higher CV=more variation.
• Least significant difference (LSD): based on the variation in a trial, this is the minimum difference between products required to call them significantly different. It might be that a corn hybrid yielded 10bu less than the trial winner, but if the inherent variability within the trial is such that the LSD (at a given confidence level) is 12bu, then these two products are not statistically different.

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!