Soybean Desiccation/Harvest Aid Reminders (Prostko)

Recently, I have been getting a few inquiries about soybean desiccation and harvest aids.  A few reminders.

1) Official soybean harvest aid rec's from from the 2024 UGA Pest Control Handbook (pages 263-264);

https://secure.caes.uga.edu/extension/publications/files/pdf/SB%2028-28_2.PDF

2) Check out these previous UGA Weed Science Blogs where I addressed this topic:

October 13, 2014:

https://ugaweedscience.blogspot.com/2014/10/avoid-early-harvest-aid-applications-in.html

October 28, 2018: 

https://ugaweedscience.blogspot.com/2018/10/do-harvest-aid-applications-of-paraquat.html

3) Check out these newer publications from LA and MS. In 2024, these two states collectively planted ~3.42 million acres of soybeans and my colleagues in these states have done a significant amount of research on this topic. Thus, they might know what they are talking about.  

    Louisiana State University: 

https://www.lsuagcenter.com/~/media/system/5/f/c/e/5fce06f97b891599afaab6b0d6fc3963/p3885_desiccatingsoybean_rh723pdf.pdf

    Mississippi State University

https://extension.msstate.edu/sites/default/files/publications/publications/P3916_web.pdf

4) Friendly reminder that I am more than happy to spend a day in any county looking at problems and/or teaching/coaching weed science.  Just give me a call (229-392-1034).  Out of town this week at a weed science meeting but after that my schedule is very flexible.

Peanut Weed Control Update - July 22 (Prostko)

 I thought you might be interested in a few pictures from our peanut weed control plots taken earlier today.

A few comments: 

1) UGA's recommended weed control program [a) starting clean, b) planting in twin rows, c) using multiple residuals at planting that get activated by irrigation and/or rainfall, and d) making timely (34 DAP) POST applications] looks very good as usual.  This location has received 14.12" of rainfall since May 1 (3.56" above average) and the residual herbicides have lasted longer than anticipated.  

2) Once again, I see no significant differences in weed control between Prowl or Sonalan-based weed control programs.

3) The only tweeks to this program would be the addition of either Cobra or Ultra Blazer to the Cadre + 2,4-DB + Dual Magnum POST treatment.  Also, could use other Group 15 herbicides depending upon grower preference (Anthem Flex, Outlook, Warrant, Zidua).  Remember, Cobra has performed better on larger pigweeds than Ultra Blazer.

4) Generally, peanut growers have all the tools that they need for weed control (except for perennial broadleaf weeds).  Just have to figure out a better way for them to be more timely?  

Carpetweed in Peanut (Prostko)

I have been getting lots of questions recently about the control of carpetweed (Mollugo verticillata) in peanut.  Check out these pictures from Ben Reeves (Berrien Co.) who sent them to me earlier today. 

A few things to chew on:

1) Carpetweed is summer annual weed native to the U.S.

2) Other common names for this weed include green carpetweed, Indian chickweed, whorled chickweed, and devil's grip. 

3) Carpetweed is listed as a controlled weed on EVERY peanut herbicide label except for Basagran (bentazon), Butyrac (2,4-DB), Classic (chlorimuron), Strongarm (diclosulam), and the POST grass herbicides [Fusilade (fluazifop), Poast (sethoxydim), and Select (clethodim)]. So...?

4) No confirmed cases of herbicide-resistance in carpetweed have been reported worldwide. (https://www.weedscience.org/summary/species.aspx)

5) Carpetweed has been in my research plots for 15+ years.  I have never failed to control it with my recommended peanut weed control programs (http://www.gaweed.com/newest-prostko-2024-control-peanut-corn-soy.pdf).

6) Possible reasons for lack of carpetweed control in 2024 are as follows:

a) Too wet?  Residual herbicides do not last as long; growers cannot get into fields on timely basis; unexpected pop-up showers occur before rain-free period is reached. 

b) Too dry? Residual herbicides do not get activated on a timely basis; big weeds + dry weather are a POST herbicide's Achilles heel.

c) Reduced herbicide rates?  Many growers are not using full labeled rates of herbicides such as Cadre (imazapic) to help prevent carryover in 2025.  We proved many years ago that this strategy does not really work.  Cotton will find Cadre in the soil when a lab analysis will not.  More importantly, when reduced rates are used and less than 100% weed control is obtained, the evolution of herbicide-resistance is greatly increased.  Yes, we can control some weeds with reduced herbicide rates (i.e. bristly starbur/Strongarm) but this tactic does not work for every weed and every herbicide. 

An Interesting Exchange (Prostko)

Thought everyone might benefit from this recent text conversation that I had with one of the best peanut/cotton growers in the state of Georgia.  Here it is. 

Grower Question?

Do you think I can apply this product [Ag-Min (30% Mn + 15% S)] with 2,4-DB?

.  

Prostko Response:

There have been some issues in the past with Mn + DB.  See below.   Also, my colleague at NC State University (Dr. David Jordan) has seen some problems as well. Last few years some weird stuff has happened.  Might be better to co-apply with fungicide.

 

Recent NC State Blog (07/03/24): 

https://peanut.ces.ncsu.edu/2024/07/manganese-and-24-db-peanut-notes-no-135-2024/

Grower Response 1 Day Later:

So I rolled the dice.  I have the ability to circulate my mixing vat to fully dissolve dry matter.  Also, my sprayer has good agitation.  I am running 15 GPA, so probably a more diluted spray solution that most.  I still made polyester.  I am telling you, not to admit that I am an idiot for not heeding your warning, but so that you can tell others that ask.  It's absolutely a no go!

Prostko Response 1 Day Later:

At least you were wearing PPE! 

Strongarm/Cadre/Cobra - Prostko

 A few quick comments based upon texts, e-mails, and phone calls this week:

1) Clethodim + Strongarm + Crop Oil + AMS Tank-Mixes????  Nothing better than good data.  See chart below.  Anywhere from 0% to 17% less grass control when Strongarm was mixed with Select.  You may recall that grass control is often reduced when POST grass herbicides are tank-mixed with certain fungicides and herbicides (i.e. antagonism).  Antagonism can be avoided by applying the POST grass herbicide first then applying the other agri-chemicals ~3 days later.

2) Cadre Programs?  Check out this picture from my peanut plots earlier this morning.  Further proof of the need for Cobra (or Ultra Blazer) + any Group 15 herbicide (Dual Magnum, Outlook, Warrant, Zidua) applied in combination with Cadre + 2,4-DB.  Most or all of the Palmer amaranth populations in Georgia have some level of resistance to the ALS-inhibiting herbicides.  

3) Is there a Cobra shortage?  According to my contacts as Valent, there are about 20,000 gallons of Cobra sitting in a warehouse in Albany, GA.  My contacts at Triangle tell me there is at least 1 pallet (180 gallons) of Cobra at their facility in Leesburg.  Not sure why some dealers are reluctant to procure some Cobra?????

4) My schedule over the next few weeks:

a) July 8-July 11: APRES (Oklahoma City, OK).  Still available via e-mail, phone, text, smoke signal, 24/7.  

b) July 12-21: I will be on vacation.  Please try to reach me via e-mail. I will be looking at my e-mails at least once/day in the early AM.  If you have an emergency (i.e. a WTF moment), shoot me a text and I will try to call you back ASAP.  Herbicide application rates, timings, rain-free periods, PHI, etc. are NOT an emergency.  All of this type of information can be found in 2024 UGA Pest Control Handbook.  However, more than happy to take those types of questions when I am in town.        

Cadre (imazapic) Review - Prostko

Lately, I have been getting a lot of calls about the use of Cadre (imazapic) in peanut.  Since we have many new county extension agents and us old folks have fading memories, I thought it might be a good time for a quick review.  Here are 10 things about Cadre you may or may not have known.   

1) The active ingredient in Cadre was first discovered in 1981 by American Cyanamid Company.  

2) Cadre was first registered for use in peanut in 1996.

3) Cadre was tested under the code number AC-263,222.  Much of the foundation research on AC-263,222 was conducted in Georgia [Drs. John Wilcut (former VT, UGA and NCSU Research Weed Scientist) and John Richburg (Corteva)].

4) Cadre was first formulated as a 70DG but is now sold a 2AS.

5) Although most peanut growers usually apply Cadre around 30-45 days after planting (DAP), it can be applied earlier.  Peanuts have excellent tolerance to Cadre.  Check out this older Georgia yield data. 

6) In some other countries (i.e. Australia), imazapic is applied preemergence (PRE).  Cadre is not labeled for PRE applications in Georgia peanuts because PRE applications are more likely to result in cotton carryover problems (and other sensitive crops) and also can be less effective on Florida beggarweed.

7) Cadre can occasionally cause "yellow flash" injury when used in peanut.

8) ALS-resistant Palmer amaranth was first confirmed in Georgia in 2000 after collecting seed from a peanut field where Cadre treated plants survived the application.

9) ALS-resistance in yellow nutsedge was confirmed in Georgia in 2021.  In this field, peanuts were grown continuously for 4 years where ~18 oz/A of  Cadre was applied during that time period.  Not the normal use pattern or rotation sequence for most of Georgia.     

10) Imazapic is sold under many trade names including Impose, Plateau, and Comrade.

"Georgia" Storm for Peanut/Soybean Tank-Mixes (Prostko)

1) Since the agent training in Tifton on June 6, I have had numerous questions about the "Georgia" Storm that I talked about in peanuts.  The commercial formulation of Storm 4SL from UPL is a pre-mixture (i.e. 1 jug) of acifluorfen (1.33 lbs ai/gal) + bentazon (2.67 lbs ai/gal).  The normal recommended use rate (by me) of commercial Storm is 16 oz/A when combined with Gramoxone (paraquat) in an early-post or "cracking" spray.  Storm @ 16 oz/A is equivalent to rates of ~11 oz/A of Ultra Blazer 2LC (acifluorfen) + ~11 oz/A of Basagran/Broadloom 4LC (bentazon). In my opinion, 11 oz/A of Basagran/Broadloom is sometimes too much in this mix.  At this rate, Basagran/Broadloom will reduce peanut leaf burn but could also reduce efficacy on some weeds in certain scenarios (i.e. larger Florida beggarweed and sicklepod). 

I use the term "Georgia" Storm when growers choose to make their own by tank-mixing Ultra Blazer 2LC @ 16 oz/A and Basagran/Broadloom 4LC @ 8 oz/A (i.e. 2 separate jugs).  These application rates are more ideal for the general weed complex that growers have in most Georgia peanut fields.  Based upon some recent price estimates, "Georgia" Storm is ~$1.75/A cheaper than the commercial Storm.  But, many growers prefer the convenience of only having to deal with 1 jug. Both Storm and "Georgia" Storm have performed very well in my 2024 research plots.  See below.    

    

2) I have had a a bunch of questions about the following tank-mixes in soybean.  When I was conducting my original on-farm tropical spiderwort research in the early 2000's, Liberty-Link soybeans were not yet commercialized (2009) and dicamba-tolerant soybeans were a pipe dream. Please note that Basagran is not labeled for use in combination with Engenia according to the latest tank-mix information (https://www.engeniaherbicide.com/tank-mix.html).  However, Basagran is labeled for use with Xtendimax (https://www.xtendimaxapplicationrequirements.com/#/intro).