EPA Proposes New Safety Measures for Paraquat (Culpepper)

Extension Agents, below is a summary of additional measures that our U.S. EPA has proposed for paraquat (full details at https://www.epa.gov/pesticides/epa-proposes-new-safety-measures-paraquat). If any of these potential requirements challenge the sustainability of our family farms please let me know by January 6, 2021.    

“As outlined in the proposed interim decision for paraquat, the agency is proposing new measures to reduce risks associated with paraquat in order to better to protect human health and the environment. These measures include:

• Prohibiting aerial application for all uses and use sites except cotton desiccation;
• Prohibiting pressurized handgun and backpack sprayer application methods on the label;
• Limiting the maximum application rate for alfalfa to one pound of active ingredient per acre;
• Requiring enclosed cabs if area treated in 24-hour period is more than 80 acres;
• Requiring enclosed cabs or PF10 respirators if area treated in 24-hour period is 80 acres or less;
• Requiring a residential area drift buffer and 7-day restricted entry interval (REI) for cotton desiccation;
• Requiring a 48-hour REI for all crops and uses except cotton desiccation; and
• Adding mandatory spray drift management label language.

In addition, EPA is proposing to allow truck drivers who are not certified applicators to transport paraquat when certain conditions are met.”

Excalia/Herbicide Tank-Mixes (Prostko)

At the recent UGA Peanut Agent Training on December 9, Dr. K. mentioned a new peanut fungicide from Valent sold under the trade name of Excalia (inpyrfluxam). Lately, all my industry friends seem to have forgotten that the crop safety/efficacy of peanut herbicide/fungicide tank-mixtures is one of my most common questions. Thus, I do not have a ton of data for this one in regards to tank-mixtures.  In 2020, I did some quick and dirty strip-trials with tank-mixes of Excalia with either Cadre or Cobra or Ultra Blazer + 2,4-DB + Dual Magnum. In those trials, I did not observe any physical compatibility problems or significant increases in peanut injury (Figure 1, 2, 3),  But, I really need to collect more replicated data.

 

Agent Training Follow Up (Prostko)

Just a few things to follow up on after our recent weed science training on December 2:

1) If you are looking for something to help you better understand herbicide modes of action (MOA), check out the Herbicide Resistance Action Committee's (HRAC) 2020 MOA Classification Chart.  A good one for your pickup truck library.

https://hracglobal.com/files/HRAC_Revised_MOA_Classification_Herbicides_Poster.pdf

2) We had some discussion about the potential residual effects of glyphosate on crops and some of the research that we are conducting.  It's a very complicated issue influenced by many factors (soil type, OM, pH, other soil cations, application rate, timing, species sensitivity).  However, I am not really worried about the residual effects of glyphosate on most major row crops grown in Georgia.  

I was asked specifically about the effects of soil pH on the adsorption of glyphosate.  In general, as soil pH increases, soil adsorption of glyphosate decreases (Figure 1).  This also happens with herbicides in other families such as the triazines (atrazine) and sulfonylureas (chlorimuron).  But, just because glyphosate adsorption is decreased as soil pH increases, it does not automatically mean it will cause excessive crop injury. 

 

Wheat Weed Management Circular for 2020-2021 (Culpepper and Vance).

Agents, our wheat weed control circular is finalized. For the most part, it remains very similar to last seasons except that we have added Axial Bold and updated our recommendations in regards to a large amount of research with Quelex.

If you would like a copy, e-mail Jenna Vance at jcsmith3@uga.edu and ask for one of the following options:

Option 1: Request laminated circulars to be mailed to you. Provide the number of circulars that you would like and provide and address to send them.

Option 2: Request a pdf version.  An email response will provide the PDF as an attachment.

Dicamba Update (Culpepper)

Extension agents, I am optimistic that we are nearing a decision by our U.S. EPA regarding registrations for XtendiMax, Engenia, FeXapan, and Tavium and their potential uses for 2021. We certainly need to thank the EPA for the tremendous effort that they have invested in this challenging process. As I have shared several times, I am optimistic that labels will be approved for use in dicamba-tolerant cotton and soybean but I am also concerned about additional restrictions that may be added to labels challenging our farmers……….of course, that is just my guess. We will have in-depth discussions regarding this topic at our Using Pesticide Wisely training platform for 2021 and at our annual extension weed training on Dec 2………….make sure you attend! Of course, Prostko is organizing the training so send him an e-mail if you have questions or thoughts.

"New" Field Corn Herbicides for 2021 (Prostko)

In the last few weeks, I have seen some publicity about potential “new” herbicides in field corn.  In many cases, these “new” herbicides are not really new just a new pre-mix of older active ingredients.  The following table summarizes a few of these “new” field corn herbicides that growers might be asking you about for use in 2021.  FYI, none of these herbicides will appear in 2021 UGA Pest Control Handbook because I currently do not have enough data to support their widespread use.  It is the general practice of the UGA Weed Science Team to collect at least 2-3 years of solid data before a new product in "officially" recommended in the Pest Control Handbook.   

Company	Trade Name	Active Ingredients	WSSA MOA	Label
AMVAC	Sinate™	glufosinate + topramezone	10 + 27	https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Sinate_Label1.pdf
	Impact Core™	topramezone + acetochlor	27 + 15	https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Impact_CORE_Label.pdf
Summit Agro USA	Shieldex®	topyralate	27	https://www.summitagro-usa.com/wp-content/uploads/2019/09/SHIELDEX-400SC-Herbicide-Label.pdf
Syngenta	Acuron GT	bicyclopyrone + s-metolachlor + mesotrione + glyphosate	27 + 15 + 9	Not yet labeled

Here are few pictures of these products from my field research in 2020 (click on pictures to make them larger):

 

Late-Season Applications of Glyphosate and Weed Seed Production (Prostko)

Now that many growers are finishing up with field corn harvest, I have been getting lots of questions about the potential effects of late-season applications of glyphosate on the production of weed seed. Very glad to see that growers/agents are thinking about this issue.  Preventing weed seed-rain back into a field is a great long-term strategy for improving future weed control programs.  

Bottom line on this issue is that late-season applications of glyphosate can be very helpful in reducing weed seed production BUT ONLY IF APPLIED AT THE RIGHT TIME!  

Check out Figures 1 & 2.  You will note that glyphosate applications only reduced weed seed production when applied early.  Generally, glyphosate applications made to plants with maturing seed were not as effective and would likely be a waste of time and money.  

Many weeds in Georgia fields after corn harvest might already have maturing or mature seed.  Thus, growers (with the help of their local county extension agent) should look very closely before blindly applying glyphosate with the sole hope of reducing weed-seed rain.