Category Archives: Soybean

Application Time of Day Affects Gramoxone Performance on Some Weeds

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With the planting season started, many people are thinking about using Gramoxone (paraquat) as a burndown for many weeds present at planting.  Gramoxone is a very good broad-spectrum herbicide that has been the go to for burndown of many winter and summer annual broadleaf weeds. With Palmer amaranth starting to emerge, Gramoxone is the only sure thing that will control it. However, it is less consistent controlling some weeds like horseweed (marestail). Continue reading

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Early Burndown Results

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Picture 1. Left Untreated – Right 40 ozs Roundup Power Max 3 Applied March 17, 2023

We have had the opportunity to observe field and demo burndowns around West Tennessee.  In general, going back “old school” and applying glyphosate alone provided very effective burndown.  This includes applications made back in mid-March when night time temperatures were below freezing (Picture 1). Continue reading

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Early Planting and Growing Degree Days

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As warmer temperatures creep into the forecast each spring, farmers and researchers alike begin to consider just how soon to pull the trigger and put seed into the ground. While these early planting dates may fall slightly outside of what is considered nominal for corn and soybean, certain situations may still provide growers a window of opportunity for early planting. Continue reading

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Importance of Using Effective Residual Herbicides in Soybean and Cotton

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2022 Palmer amaranth escape Engenia + glyphoste PRE/ followed by Engenia + Glyphosate applied POST. (Picture 1)

Increase in input costs and lower relative commodity prices compared to last year may tempt some to forgo using a PRE this spring.  Since glyphosate and dicamba have actually gone down in price, it may be tempting to try this combination near planting, then hope that dicamba will provide enough residual weed control to hold until those herbicides can be applied again early POST.   Continue reading

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Breaking the Green Bridge

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As general rule, no-till production increases the risks from pests including slugs, cutworm, threecornered alfalfa hopper and several below ground pests such as wireworm and southern corn rootworm. Tillage is not an option in most of Tennessee’s agricultural landscape. This leads entomologists to recommend spring “burndown” applications 4 weeks in advance of planting. The goal is to “break the green bridge” or eliminate alternative hosts (weeds, cover crops) well before planting the cash crop.

However, making burndown applications 4 weeks prior to planting isn’t always possible or it doesn’t align with the goals of having cover crops. One way to help mitigate potential insect issues in late burndown is to add a pyrethroid insecticide with your herbicide application or within 7 days of planting. Beware blooming and pollinator attractive cover crops (vetch, brassica species) may have foraging honey bees and pyrethroids should not be utilized until the plants are not longer attractive to pollinators (desiccated or senescing from herbicides).

Utilizing insecticide seed treatments will offer protection against pest insects that may feed on your cash crop. If you are planting green (not burning down cover crops until after planting) I highly recommend a robust insecticide seed treatment and a pyrethroid insecticide that is included with the burndown herbicide. In corn this would be Poncho 500 or 1250, in soybeans Gaucho or Cruiser treated seed and in cotton Gaucho or Aeris based treatments will offer adequate protection from most below ground and some above ground pests. Keep in mind, seed treatment residual activity is strongly influenced by environmental factors, plant growth and amount of AI on the seed.

Cutworm and cut corn plant
Cutworm and cut corn plant

Cutworms in corn and cotton are uncommon but can be a serious pest. Pyrethroid applications within a week of planting will significantly reduce the risks of cutworm issues at low cost. Insecticide seed treatments are normally not enough to control cutworms and Bt traits in corn and cotton can offer mixed results depending on the traits. Three gene corn and cotton (those that include the Vip trait) provide better cutworm control than dual gene corn and cotton (V2TP, BG2 etc).

Overall, I like to see farmers planting in grave yard dead fields of weeds or cover crops but that isn’t always the case. Providing protection for your cash crop, at a relatively low expense, may help avoid the painful and costly decision to replant.


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PRE and POST Options for Prickly Sida (Tea Weed) Control in Soybean

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Prickly sida or tea weed has increasingly become more of an issue in soybeans.   There are two reasons for this.  First, the Group 15 herbicides (Dual Mag, Warrant, Zidua) are the most common PRE-applied herbicides utilized.  Though that group of herbicides provides good residual control of pigweed and grasses, it provides no help on sida.  Second, is that glyphosate nor dicamba has ever been very effective on this weed.  The only POST option that can give some control is Liberty.  However, even Liberty is limited to controlling only very small (<3”) prickly sida. Continue reading

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It is “Burndown Time in Tennessee.”

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Failed glyphosate + dicamba burndown on ryegrass before corn planting in 2022

The combination of some lingering supply chain issues, most notably Sharpen and Verdict are in tight supply, with the ever-increasing presence of herbicide resistant weeds has made burndown time more of a challenge. On a positive note, glyphosate is in great supply and down in price about 40% compared to last year. Continue reading

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2022 Soybean Variety Trials in TN – Now Available

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Results from the 2022 TN soybean variety trials are now available as pdf and excel files and will be posted at Seventy-five varieties were evaluated in small plot replicated trials (REC) at nine locations and fifty-seven varieties were evaluated in three to nine locations as non-replicated large strip plots (CST).  Quality and agronomic traits are reported for the REC trials and disease data are reported for CST trials.  A summary of varieties that were in the yield “A group” (not statistically different from the top yield within each test) in either the REC or CST trial can be viewed here 2022 Soybean A Table.

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