Preplant Burndown Options for Peanut (Prostko)

In the last few days, I have gotten a few questions about preplant burndown options for peanuts.  Here a few thoughts to consider:

1)    Primary burndown herbicides will either be glyphosate or paraquat.  As we get closer to planting, paraquat might be preferred if a quicker burndown is needed.

2) Potential tank-mix partners with either of the above herbicides include the following:

a.    2,4-D (16 oz/A) - will help improve the control of wild radish and primrose.  Plant-back restriction for peanut based upon UGA research is 7 days.

b.    FirstShot (0.5-0.8 oz/A) - will also help improve the control of radish and primrose.  May also be useful in fields were off-target movement of 2,4-D is a concern.  Peanut plant-back restriction for FirstShot is 30 days.

c.    Aim or ET (1-2 oz/A) – either one of these herbicides can be useful in preplant burndown situations where annual morningglory plants (except smallflower) have already emerged. Aim can be applied anytime preplant up until 24 hours after planting. ET can be applied anytime preplant but before peanut emergence.

3) Growers who want to get early residual control of pigweed, especially when there is a potential long delay between application and planting, may want to include Dual Magnum (16 oz/A), Warrant (48 oz/A) or Valor (2 oz/A) in the burndown.  If Valor is used in the preplant burndown at least 30 DBP, an additional 2 oz/A can be used PRE after planting.  Valor will also help improve the POST control of radish and primrose (+10-15%).   I must admit that I would prefer either Dual or Warrant for residual control in this situation to help protect Valor from potential resistance issues.  There are no peanut plant-back restrictions for Dual or Warrant.

Zidua for Morningglory Control in Field Corn (Prostko)

At the last few grower meetings that I attended this winter, I was asked a few questions about the effectiveness of Zidua (pyroxasulfone) for annual morningglory control in field corn.  Most, if not all, of my data with this herbicide is on annual grass and Palmer amaranth control.  Thus, I must rely on my colleagues around the country to see what they have observed.  Figure 1 is a summary of the morningglory control ratings for Zidua as published by different land-grant universities.  It is obvious from these ratings that Zidua is not considered to be an outstanding herbicide for the control of morningglory.  

With that said, I still think that Zidua can be an effective component of a field corn weed control program in Georgia (Figure 2). Growers who are interested in using Zidua in field corn should do so for the following reasons:

a) Zidua is a new herbicide. Its always fun to try something new and sometimes herbicides perform slightly differently on individual farms.  
b) For those concerned about atrazine and PPO resistance, Zidua offers an alternative mode of action.  Zidua is a very-long chain fatty acid inhibitor similar to Dual Magnum or Warrant.
c) Zidua provides good to excellent residual control of pigweed and most annual grasses. Zidua may be slightly more effective than Dual or Warrant on Texas panicum (buffalograss) but is less effective than Prowl or Sonalan.
d) Zidua is a low use rate product (1.5 oz/A).

More information about the use of Zidua in field corn can be obtained on page 140 of the 2014 UGA Commercial Pest Management Handbook.  

Figure 1.  Annual morningglory control ratings for Zidua.

Figure 2.  Weed control in field corn with Zidua (2013).

Reflex Labeled for Georgia Watermelon, Squash, and Pumpkin (Culpepper)

These new herbicidal tools are a result of cooperative efforts involving The University of Georgia, Syngenta, IR-4, The Georgia Department of Agriculture, The Georgia Agricultural Commission for Vegetables, and Industry.  It is critical that agent’s help growers understand that their specific production practices may alter weed and crop responses to recommended herbicides. 

Important Points to Remember:

1.  Growers must have a label in hand when using Reflex in these crops.  These labels are written by Culpepper and Syngenta so if there is any confusion let me know.

2.  Agents MUST NOT give growers any indemnified label.  Growers must follow the steps below to obtain their own label.  The process of growers obtaining labels is actually the method being used to indemnify the use of Reflex in these crops.  If an agent was to provide a grower the label, it may make the agent or even UGA liable if issues were to occur. 

3.  Growers must evaluate these programs on limited acres until gaining experience.  Keep in mind these labels are developed from 10 to 15 studies conducted primarily by my research here in Georgia; most other pesticide labels are developed from over 200 replicated trials conducted by dozens of scientists across the country.

  

4.  I have created a watermelon circular, similar in format to the cotton circular.  The circular should be up on our website at www.gaweed.com by March 12, 2014.  If you would like laminated copies for your growers, e-mail me the number of copies that you would need and a shipping address.

5.  Support Syngenta and use Reflex; no generic company has shown any desire to support such challenging label development!!!!!!!!!!!!

Obtaining the label:

1.  Go to www.farmassist.com

2.  Select products along top bar.

3.  Select indemnified labels (4^th one down).

4.  Login (first time users create login and password).

5.  For state, select Georgia and for product, select Reflex in this scenario (play around and see

our other labels) and then submit.

7.  Select the Reflex label and crop of interest and submit.

8.  Accept waiver; this is the process making the label an indemnified label.

9.  Print label and have present during application.

Brake F2 Labeled for Georgia Cotton (Culpepper)

The Section 18 Emergency Use Exemption for Brake F2 in cotton has been approved by the EPA and GDA.  Thus, the product is labeled for use during 2014.  

Important Things to Remember:

1.  Apply preemergence behind the press wheel at 16 oz/A; do not apply over cotton.  It is also labeled preplant but Valor and/or diuron are better options.

2.  Brake F2 is a mixture of fluridone and fomesafen; the fluridone will require at least 0.6” of rainfall or irrigation for activation.  Both active ingredients are effective on pigweed.

3.  Suggest rotating only to cotton or peanut in 2015.  If the crop is lost, must replant back to cotton.

4.  The product is quite pricey.

5. A Brake F2 system should provide control similar to that achieved with current recommended programs; although, less injury from Brake F2 may be noted when compared to alternative preemergence herbicide options.

6.  Slides that I used this winter should be up on our UGA Weed Science web site by March 10, 2014 (www.gaweed.com).

7.  Brake F2 Label was attached to the original e-mail that was sent to you.

Warrant Receives Peanut Label (Prostko)

Warrant recently received both federal (January) and state (February) approvals for use on peanuts in Georgia. Here are a few of my thoughts regarding its potential use in 2014:

1) The current supplemental label only permits PRE and/or EPOST applications (before flowering).  

2) Of these 2 timings, I would prefer to see EPOST applications of Warrant tank-mixed with Gramoxone + Storm + NIS.  

3) At this point in time, I have NOT observed any real differences in weed control between Dual Magnum and Warrant based peanut weed control programs (Figure 1).  However, there is some data that suggests that Warrant might be a better choice for non-irrigated fields.

Figure 1.  Dual Magnum vs. Warrant Based Weed Control Programs

4)  A copy of the current supplemental Warrant peanut label can be viewed at the following location:

http://www.cdms.net/LDat/ld9KA011.pdf

5)  I have made some suggestions to Monsanto that hopefully will result in a better and more usable label in the near future.

Peanut Yields and Cobra + 2,4-DB (Prostko)

Frequently, peanut growers get concerned when they make herbicide applications that "burn" their crop.  One of the herbicides that can cause this type of injury is Cobra (Figure 1).   Recent results from tests conducted in Florida reconfirm that the injury caused by Cobra or Cobra + 2,4-DB is cosmetic in nature and does not negatively impact peanut yields (Figure 2).  In these tests, Cobra or Cobra + 2,4-DB treated plots yielded 97-105% of the non-treated check plots. Cobra or Ultra Blazer + 2,4-DB is recommended for the control of Palmer amaranth in peanut fields when Cadre is not a viable option due to ALS-resistance or crop rotation concerns (page 460 of 2014 UGA Pest Control Handbook). 

Figure 1.  Peanut leaf burn caused by Cobra.  

Berrien County Atrazine Resistance - Part 2 (Prostko)

In my last blog, I informed you of the recent discovery of atrazine-resistant (AR) Palmer amaranth in Berrien County.  After a more thorough investigation by Berrien County Agent Fast Eddie Beasley, it was discovered that the corn rotation in this field was shorter than expected (Figure 1).  Because this rotation is different from the fields where AR-Palmer was first confirmed in Georgia, there is some concern about how the resistance occurred.  Here are a few things that you might want to consider before thinking that the sky has fallen:

1) AR is not a brand new phenomenon.  The first (ever) reported case of herbicide resistance was AR-groundsel (Senecio vulgaris) way back in 1970 in the Pacific Northwest.

2) AR-Palmer was confirmed in Georgia in 2008 (Macon County).  Thus, the UGA Weed Group has had 6 years to work on this problem.  As indicated in the previous blog, numerous other herbicides are available for use in field corn that will provide outstanding pigweed control (page 155 of 2014 UGA Pest Control Handbook). However, atrazine is still very much needed in our corn weed control programs for troublesome weeds such as sicklepod and morningglory.

3) It is possible that AR-Palmer evolved in this field via pollen movement or physical seed movement (birds, equipment, animals, gnomes, etc.).

4) It might also be possible that AR-Palmer evolved in this field due to the fact that the resistance is metabolism-based rather than target-site based.  It has been documented in other weeds species with metabolism-based resistance that cross-resistance can occur in the absence of selection pressure.  This has been confirmed in some ACC-ase resistant Rigid ryegrass (Lolium rigidum) populations that were also cross-resistant to ALS herbicides that were never used in the field.  Mother Nature at its finest (i.e. genetics and evolution)!!!!

5) Herbicide resistance is a complicated issue for sure.  Consequently,  it is very important for our growers to be proactive and make every effort to delay the evolution of herbicide resistance in all of our crop production systems (tillage, cover crops, crop rotations, mode of action rotations, hand-weeding, soil seed-bank management, etc.).