Late-Season Peanut Questions (Prostko)

A couple of quick answers to some peanut questions that I have been getting over the past week or so:

1) Can I tank-mix Mn fertilizers with herbicides and/or fungicides?

Recent research from NC State University indicated that manganese did not affect the efficacy of Select, Poast, Cadre, Pursuit, 2,4-DB, Abound, Bravo, Headline, or Folicur.  Common ragweed control with Cobra was reduced 6% by dry Mn sulfate but not liquid Mn.   (Peanut Science 2012 39:1-8)

2) What weeds can be controlled using non-selective applicators (NSA) such as the Weed-Wiper or ropewick?

UGA has data to suggest that Palmer amaranth, Florida beggarweed, and sicklepod can be controlled late-season with NSA using a 50% solution of paraquat.  Please refer to page 452 of the 2014 UGA Pest Control Handbook for additional information.  Remember that the only benefits of this type of application would be improved harvest-efficiency and fungicide spray deposition.  It is way too late to recover any competition related yield losses.

3) Is there anything that can be done to help control Benghal dayflower/tropical spiderwort at this time of the year (i.e. 100+ day old peanuts)?

a) No!!!! Revenge sprays are not practical!!  Dayflower/spiderwort plants at this time of the year are too big to control with herbicides.  Additionally, late-season applications of herbicides such as Strongarm could have a significant impact on 2015 crop rotations.  Although Aim can be used as an harvest-aid, previous research has shown that single applications to 8-10" tall spiderwort plants provided < 45% control.

 

Tank-Mix Update (Prostko)

I recently had the chance to evaluate a few odd tank-mixes on peanuts (GA-12Y) planted on May 14. These included the following:  Cadre @ 4 oz/A + Diamond @ 9 oz/A + Absolute 500 @ 5 oz/A + Induce @ 0.25% v/v; Cadre @ 4 oz/A + 2,4-DB @ 18 oz/A + Acephate @ 6 oz/A + Induce @ 0.25% v/v; and Cadre @ 4 oz/A + 2,4-DB @ 18 oz/A + Dual Magnum @ 16 oz/A + Priaxor @ 8 oz/A.  Here are a few comments regarding these particular mixes:

1) All treatments were applied on June 17 @ 8:50 am (77 F, 92% RH).
2) At 3 DAT, only the Cadre + DB + Dual + Priaxor treatment caused > 10% leaf burn (Figure 1).  All treatments caused the typical Cadre "yellow flash" symptom.
3) At 10 DAT, leaf burn from all treatments was < 10%.
4) Only 91,389 tank-mixtures to go before I have all the answers.
5) FYI, I will be on annual leave next week and unable to return phone calls.  However, I will respond to e-mails early in the AM.  

Figure 1.  Peanut injury caused by Cadre + DB + Dual Magnum + Priaxor (3 DAT).

Preliminary 2014 Peanut Weed Control Results (Prostko)

Someone once said that a picture is worth a 1000 words.  Check out the picture below for a quick review of some peanut weed control plots that were rated earlier today.  I have yet to observe any real differences in weed control between Dual Magnum and Warrant based peanut programs.  Remember that Warrant is not yet labeled for use on peanuts after flowering.

Some Answers to Common Questions (Prostko)

I can tell things are busy right now because my phone has been ringing off the hook.  Here are some quick answers to some common questions that I have gotten recently:

1) Can I spray paraquat + Storm + Dual cracking treatments on peanut at night?

For now, I would say that this might be a bad idea since there is little or no peanut data to support this type of application.  For the past 17 years, all of my cracking treatments have been applied between the hours of 6 am to 9 am.  Perhaps, night applications might be something I should look into for 2015.  Research conducted in Arkansas suggested that volunteer corn control with paraquat would be greater at sunset than at sunrise.  In Texas, cotton dessication/defoliation with paraquat was better when applied at 6:00-6:30 pm compared to earlier in the day.  However, remember that many plants experience diurnal (night) leaf movements which could impact spray coverage which is extremely important for the success of any paraquat treatment.

2) Can I tank-mix Dual Magnum with peanut fungicides to get longer residual control of Palmer amaranth?

Yes.  In 2013, I tank-mixed Dual Magnum with the following fungicides at 52 DAP (R2 stage of growth, 8" tall): Tilt/Bravo; Headline; Abound; Provost; and Fontelis.  These tank-mixtures resulted in approximately 10% peanut leaf burn.  This injury had no effect on final yield.  A similar test is being conducted in 2014.

3) Why do I not want Georgia soybean growers to use Valor, Prefix, or Reflex PRE?

A) Georgia growers are already over-using the PPO herbicides in cotton and peanut.
B) Almost every acre of soybean in Georgia will need a POST treatment for Palmer amaranth control.  The only soybean herbicide that will provide both PRE (residual) and POST control of Palmer amaranth is Reflex.  Thus, Valor, Prefix, or Reflex PRE followed by Reflex POST is a very bad idea!!!!!!!!!
C) Georgia soybean growers should seriously consider using alternative PRE herbicides such as Dual Magnum, Warrant, or Boundary.

Replanting Cotton after Using Warrant (Culpepper)

1. Label: There are no preplant restrictions on the label for cotton which means you could apply Warrant anytime prior to planting……or replanting.

2.  Culpepper thoughts:

A. I strongly discourage you from following Monsanto’s preplant label recommendation for Warrant; our data suggests injury from Warrant can be significant if planting to quickly behind a Warrant application.

B. Our data and experiences suggest the following:

No-till into 3 pt Warrant	Strip-till in to 3 pt of Warrant
7 days = 30 to 50% stunting	7 days = 0 to 20% stunting
14 days = 0 to 30% stunting	14 days = no stunting
21 days = no stunting	21 days = no stunting

C.  Things to Consider:

1.  I have no clue how much Warrant is in the planting zone after 4 inches of rain.  If the Warrant is gone then these suggestions are conservative but these results have been consistent over the past 3 years. 

2.  We are developing an irrigation system to help us use research to better understand where herbicides are located in the soil profile and how active they are after varying amounts of rainfall/irrigation have occurred.  This system should be operational for next season’s crop.

3.  I have gotten so many calls about Warrant, I will have several different demos available for viewing on our June 26 tour.

**For Agents Eyes Only!

Counter in Cotton (Culpepper)

1. Label: The Counter label prohibits the use of Diuron, Cotoran, Caparol, Cotton Pro, Staple, Pyrimax, and Envoke from use when using Counter.

2.  DuPont:  Does not support or recommend the use of Staple following Counter use in cotton.

3.  Culpepper:

A.  I am clueless why this label was brought forward without any real understanding for potential interactions with Counter and several of the most commonly used herbicides in cotton.

B.  I have one study in progress including all of these herbicides; no injury issues so far.

 

C.  Follow the label.

D.  If you have questions call Bob Kemerait (229-392-0498) or Gerald Harrison (229-392-2590) or better yet, give them both a call.

E.  Do not call me about this issue because I really cannot add anything.  Anytime we talk I share data results; however in this case, I have no data so I don’t have anything to say. 

F.  If you are obtaining experiences this season please share those with me so we can begin generating the data that should have been developed before the label was released. 

** For Agents Eyes Only!

Peanut Injury Update (Prostko)

In the past 2 days, I have received numerous phone calls, texts, smoke signals, homing pigeons, and e-mails about peanut injury caused by Valor.  Peanut fields planted the week of May 5 that were hit by the heavy rains on May 14-15 are likely to have some level of injury (Figure 1).  Here are a few thoughts to consider:

1) Valor injury should not be a surprise to anybody since this phenomenon has been observed for 13 years.  Cracking peanuts (+1-2 weeks) treated with Valor that receive heavy rainfall will be injured almost all the time!!!

2) There is a good amount of UGA data to suggest that, in most cases, the peanuts will recover from this injury without yield loss even at a 2X rate (i. e. 6 oz/A) (Figure 2 + 3).

3) Recent UGA research conducted by Drs. Jason Sarver and Scott Tubbs would suggest that there is no yield or economic benefit to replanting a peanut field if populations are at least 2.5 plants/ft (single row) or 3.0 plants/ft (twin row).  Thus, I would not worry too much about Valor injury unless plant populations fall below these levels (assuming the stand is uniform and not skippy).  

4) Contrary to older dogma, peanut j-rooting is not always caused by herbicides such as Dual or Warrant.  Today, I found numerous peanut plants in my untreated plots (i.e. no herbicides) that are exhibiting this symptom (Figure 4).  Many other factors can cause j-rooting including individual seedling vigor, environmental conditions (cold/wet), and soil compaction. 

Figure 1.  Valor Injury in Peanut

Figure 2. Peanut Yield Response to Valor - 2009

Figure 3.  Peanut Yield Response to Valor - 2013

Figure 4.  J-rooted peanuts not treated with any herbicide.