2018 Final Yield Grids 2019 Herbicide Strategies  12/13/18 1:25:31 PM

 

 

2018 FINAL YIELD GRIDS

 

 

 

The following is the final 2018 version of the Asgrow and DeKalb yield grids for our general area.  The annual idea of this data set is to provide insight of genetic performance under multiple locations, management styles, planting dates, etc., and test the genetics of the relative maturities of the Asgrow and DeKalb brands against some of the competitive industry standards.  It is also meant to take a look at the new genetic offerings from the respective brands to see how they measure up against some of the tried and true genetics.  We also look at the consistency of the products from year to year—this is found at the bottom of the sheets and gives you the percentages/consistencies of performance for the past three years…..For point of reference and ease of viewing---if performance of a hybrid/variety in a plot is highlighted in yellow—it finished in the top 3 of the plot—if colored in purple—it finished in the top half of the plot.    In summary, if a hybrid/variety finishes in the top 3 or top half of the plot and does that in multiple locations, management styles, planting dates, etc., it tells of it’s consistency of performance this year…..If it does that same performance for the past 3 years, it goes even further in telling it’s story of yield and adaptability to your acre. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2019 HERBICIDE PLANNING

 

 

 

We have talked about herbicide programs many times in the past. This winter will be no different as we discuss what worked and what didn’t work in 2018.   This usually is focused around weed escapes and/or Roundup resistance development of various weed species.  Roundup Ready to Xtend has become more common place in our genetic selections we are currently making for the 2019 season.  If you know you have Roundup Resistant weeds—why use Roundup based products?  Just use a dicamba based program.  You may be considering why you would include any glyphosate compound at all in your 2019 planning process. 

 

 

 

Here are a couple of thoughts to consider. 

 

 

 

Stories about glyphosate (the active ingredient in Roundup, and a host of other compounds) failures and glyphosate resistant weeds promote concern about the use of Roundup based herbicide programs. These concerns have circulated for years since the introduction occurred into row-crop use back in the mid-late 1990’s.  Most of these stories have historically created fear of using beneficial technology and provide use recommendations not based not on scientific data but largely on emotions and assumptions.  This can create grower concern about using technology that has proven to provide many benefits including facilitation of conservation tillage systems, excellent weed control and excellent crop safety.  As the years have gone by, broad spread application have continued to develop, and the incidence of more weeds  (waterhemp/marestail mainly) escaping the treatment have also increased.

 

 

 

 

 

Remember in the early 1990’s when triazine resistance developed?  We had these same questions regarding the value of any triazine/atrazine-based compound on the weeds it couldn’t kill anymore.  We then focused our thought processes on weed species that it did and continues to work well on alone and in combination with other herbicides—This is called a synergy effect in that one active ingredient alone may have only a suppression in weed control on any one weed species, but, combined with additional active ingredients/modes of action, makes other herbicides perform better.   

 

 

 

 

 

Does this mean that if one application of Roundup doesn’t kill the weeds—those weeds are automatically resistant to glyphosate??

 

 

 

Monsanto introduced Roundup herbicide in 1974, providing growers with a new and effective tool for broad-spectrum weed control.  Roundup Ready crops were introduced beginning in 1996, providing growers with additional tools to obtain excellent weed control and crop safety along with greatly improved ease, flexibility, and potential cost savings.  Both of these novel technology introductions have revolutionized weed control practices in crops since then.  It is hard to argue that Roundup agricultural herbicides and Roundup Ready crops are excellent, economical solutions to weed control while offering a relatively low risk of resistance development.  It’s success has also created an attitude over the years that it would ALWAYS work on ANYTHING at ANY Growth Stage..  The thing I think that has been understated is this:  Roundup treatments are no different than any other herbicide in that 1) it’s works better on small actively growing weeds,(less than 6”) in height 2) you can achieve “better” weed spectrum control by using a tank-mix, and 3) a combination of application timings and modes of action will also provide better control.  

 

 

 

Over the past 10 years or so, weed species such as pigweeds (waterhemp, palmer amaranth, redroot pigweed,) ragweed, and marestail, have become routine candidates for weed control escapes from a Roundup treatment—primarily in soybeans.  This past year was no different as we have experienced a number of fields treated with a glyphosate based treatment applied that had marestail/pigweed escapes from the original treatment.

 

 

 

                        WHY?

 

 

 

  1. Why does the treatment kill one waterhemp plant completely and 3 feet away NOT kill another waterhemp plant of the same size?          

  2. Why is there seemingly more escapes occurring every year?

  3. Why do certain fields where tillage was done earlier have more weeds and more escapes?

     

    Weeds have evolved resistance to 23 of the 26 known herbicide sites of action and to 163 different herbicides. Herbicide resistant weeds have been reported in 92 crops in 70 countries.

     

    There are now 18 confirmed weed species resistant to the active ingredient glyphosate in the U.S—6 in Nebraska.  Glyphosate has no soil residual, and is tightly bound to soil organic matter and dust.  These two facts play important roles in why there continues to be weed escapes after application—even with high use rates. These facts also aid in the potential development of resistance.  

     

    I have seen most escapes in the areas that are directly behind where the sprayer traveled in the field.  I have also seen many escapes along roads where excessive dust from the adjacent road has covered the leaves.  Dust/dirt on the weeds leaves will limit/tie up the glyphosate from being absorbed/translocated in the plant.  Areas that incurred tillage this year are saw increased weed pressure—even with the dry weather.  This is likely due to the weed seed dormancy being broken via the tillage practice in the soil.  I won’t argue the justification for the tillage, I just notice that weed pressure is generally greater in areas that have had a tillage pass since that last cropping season.  

     

    I don’t think that every waterhemp/marestail plant is resistant to glyphosate.  I don’t think that just because a certain weed species doesn’t immediately die after a Roundup application, it is automatically Roundup resistant.  The inconsistency of the weed control is LIKELY a matter of really all of the following:

     

    --late application timing with no increased rate change for larger weeds

    --the non-use of an additional tank-mix herbicide for control of these weeds in the treatment

    --hot, dry, dusty dirty conditions at application time—actively growing non “dirty” weeds are easier to kill.

     

    As in the past, I encourage you to consider the use of pre-emergence applications along with tank-mixed post-emergence applications if you are having problems controlling weeds postemergence with a single application.   Here are some reasons why:

     

 

  1. Weed populations pose a universal soil water, nutrient use, and weed competition situation.  
  2. Many times contact/burn down/non-residual treatments are made when the targeted weeds are too large in size for the treatment to effectively work.
  3. The time of weed emergence influences which species will be the most serious weeds in a given crop production practice and allows you to predict what application is priority given the weed species present. It also determines which weeds will be most susceptible to certain control measures.  Multiple mode and multiple application combinations reduces that chances of most species escapes and/or development of resistance to any one herbicide mode of action.

 

 

 

The wide range of species present in corn and soybean complicates prediction of weed emergence patterns. Many factors, such as tillage system, crop rotation, weed control history and weather patterns regulate the weed population of a given field. However, general emergence trends among species are predictable. See the table below, which details the emergence sequence of problem weed species of crop production in our geography.

 

Lambsquarters, velvetleaf, and foxtail species are relatively early emergers, while tall waterhemp, common cocklebur, morninglory, and crabgrass generally emerge later in the growing season.  As the crop canopies, germination of new weeds will be limited. This usually reduces competition from later-emerging weeds.

 

Table 1. Weed seed germination and emergence characteristics

 

of several weeds of row crops in the north-central United States1.

 

 

Weed Species

Season of Emergence2

Emergence Period (wk)

Emergence Depth3

Half-life4 (yr)

Germination Stimuli5

 

Horseweed

Fall/early spring

 

 

 

L

 

Shepherds-purse

Fall/early spring

S

 

2.8

C, L, N, T±

 

Field pennycress

Fall/early spring

 

M

5.7

L, T±, A

 

Giant ragweed

GDD <150

03-Feb

 

0.3

 

 

Common lambsquarters

GDD <150

07-Mar

S

7.6

L, T±, N

 

PA smartweed

GDD <150

07-Mar

 

4

 

 

Annual sunflower

GDD <150

07-Mar

 

0.3

 

 

Redroot pigweed

GDD 150-300

10-Aug

S

2.2

L, H, T±, N

 

Common ragweed

GDD 150-300

07-Mar

M

1.4

C, L, T±

 

Velvetleaf

GDD 150-300

10-Aug

D

2.3

A

 

Giant foxtail

GDD 150-300

10-Aug

 

0.8

 

 

Yellow foxtail

GDD 250-400

07-Mar

D

4.5

C, N

 

Black nightshade

GDD 250-400

07-Mar

M-D

L, T±, N

 

 

Common cocklebur

GDD 250-400

07-Mar

D

5.6

C, T±, (D)

 

Wild proso millet

GDD 250-400

07-Mar

 

 

 

 

Large crabgrass

GDD >350

07-Mar

M

1.2

C, (D)

 

Fall panicum

GDD >350

07-Mar

 

 

 

Waterhemp

GDD >350

10-Aug

 

2.4

 

 

Morningglory

GDD>350

10-Aug

 

 

 

 

1 The information in this table is based on Tables 1 and 3 in Davis (2004), and an extensive literature review

 

 review of weed seed ecology research by Charles A. Mohler.

 

 

2 GDD = growing degree-days F (base temperature 48°F).

                                          GDD<150 – emerge several weeks before corn planting

 

GDD 150-300 – emerge shortly before or during corn planting  

 

GDD 250-400 – emerge near the end of corn planting; GDD>350 – emerge after corn emergence.

3 S = shallow, most seeds emerge from surface or top 0.5 in of soil profile;

M = medium, most seeds emerge from top inch;

D = deep--most seeds emerge from top 2 inches, and a few can emerge from greater depths.

     

4 About 6 to 7 half lives required to eliminate 99% of seed from the weed seedbank.

 

5 A = aeration; C = chilling period; H = high soil temperature; L = light; (D) = not responsive to light; N = nitrate; T± = fluctuating soil temperatures.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table adapted from: Manipulated Weed Seed Banks to Promote their Decline. March 2010

 

 

 

All post-emergence herbicides are suspect to failure when weeds present are too large for the treatment use rates.  Herbicides will most always control weeds the best when the applications are made to smaller, actively growing weeds prior to them getting out of the application window.  If you have had prior problems with some of the listed weeds, it might be time to consider the products which you are using, your ability to get the treatment applied in a timely manner, and your satisfaction/convenience with your current programs.  There are many  “look-a-like programs” from various companies, which may promise weed control, however they may fall short with your particular weed problems.

 

 

 

 
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