Avoid Early-Harvest-Aid Applications in Soybeans (Prostko)

Soybean growers with ants in their pants, who want to use paraquat as a harvest aid, should be warned not to apply too early.  Early applications (>40% seed moisture) will likely result in significant soybean yield loss as a result of reduced seed weights (Figure 1).  The 40% seed moisture content roughly coincides with the R6.5 to R7 stages of growth.  R6.5 = Full Seed = all normal pods on 4 uppermost nodes have pod cavities filled.  R7 = Beginning Maturity = one normal pod on main stem of all plants has reached mature color (Figure 2). Official UGA soybean harvest aid recommendations can be found on page 517 of the 2014 UGA Pest Management Handbook.

Figure 2.  Soybean Reproductive Growth Stages

Fierce Section 24(c) Label For Wheat in GA (Culpepper) - For County Agents Only!

Fierce, active ingredient pyroxasulfone and flumioxazin, just obtained approval for postemergence applications in Georgia wheat as a Section 24(c) Special Local Need Label. 

Valent and I have developed this use to help growers struggling with ryegrass that is resistant to postemergence herbicides.  Our intentions for the 2014/2015 crop are to have a controlled use of Fierce allowing Valent and UGA Cooperative Extension the chance to determine if the herbicide can be used to effectively manage problem weeds while having acceptable crop injury. 

Application of Fierce:

1.  Follow the label exactly; it is listed below.

2.  Wheat must be planted 0.75 to 1 inch deep and cannot be broadcast spread.

3.  Apply Fierce at 1.5 oz/A in ONLY water when wheat is between the spike and 2-leaf stage; ryegrass needs to be spike or smaller.

4.  Apply Fierce only in water.  Notice I just mentioned twice that you cannot have anything in the tank other than clean water and the herbicide; no exceptions so don’t even call and ask!

5.  Must use 10-15 GPA; prefer 15 GPA if weeds are emerged.

6.  Do not apply with airplane.

7.  Only for wheat!!  No need to ask about other grain crops at this time, only wheat.

On-Farm Evaluations:

Several agents have been contacted directly and asked to work with Valent conducting split field comparisons treating half the field with Fierce and half the field with the grower’s standard program to improve our knowledge.  If I have not contacted you but you have a burning desire to take a look, contact your local Valent salesman which should be one of the following: 

John Altom: 352-316-1366; David Yoder 850-377-8137; or Jerry Dowdy: 803-422-6605

Crop Injury:

1. Greatest potential for injury occurs when 1) label recommendations are not followed and 2) when open/cracked seed furrow allows herbicides to directly contact the seed, when seed are planted to shallow, or when seed are planted in a deep furrow that allows herbicide concentration after a rain/irrigation event while wheat is growing. 

2.  Even when following the label, injury will occur in some environments.  This is why we are taking such a conservative approach.  With that said, our research suggests the benefits in weed control far outweigh injury concerns when following the label; you guys need to tell us if the research is accurate or not.

3.  Strongly suggest growers only try a field or two; do not treat the farm!!!!

Limited Product:

1.  We believe there will be enough product to treat about 6000 acres which is limiting but exactly what we need for this season.  

Dual Magnum Label for Georgia Broccoli, Cabbage, Cauliflower, Collards, Onion, Bell Pepper, Beans, Cantaloupe, Watermelon, Carrot, Sweet Potato, and Tomato (Culpepper)

Over the past several years, I have worked with Syngenta to increase Dual Magnum herbicide options for vegetable growers as well as to improve our previously used labels; new labels are now available. A limited amount of this information will be available through the 2015 UGA Pest Control Handbook but a label must be in hand at time of application and the label will provide much more prescriptive information. 

Important Points:

1.  Growers must have a label in hand for these uses.  These labels are written by myself and Syngenta so if there is any confusion let me know.

2.  Agents MUST NOT give growers any indemnified label; agents should obtain their own label for knowledge.  The process of Growers obtaining labels is actually the method being used to indemnify the use of Dual Magnum 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 should 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 in Georgia; most other pesticide labels are developed from over 200 replicated trials conducted by dozens of scientists across the country.  

4.  Support Syngenta and use Dual Magnum; 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 Dual Magnum in this scenario (play around and see our other labels) and then submit.

6.  Select the Dual Magnum 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.

Deep Turning Reduces Annual Ryegrass Populations (Culpepper and Webster)

Georgia wheat production is in jeopardy due to herbicide resistant ryegrass.  Ryegrass resistant to all currently labeled postemergence controlling herbicides has been documented and is becoming very common.  Heavy ryegrass infestations, if uncontrolled by poor management or herbicide resistance, can eliminate production. 

Ryegrass has proven that it is capable of rapidly developing resistance to any and all herbicides used for management; even more so than Palmer amaranth.  A systems approach to management is the only sustainable option and may include rotating herbicide chemistries, rotating crops, and maybe even implementing deep tillage in the more severely infested fields.

Current research is being conducted to determine the potential benefits for deep turning to reduce annual ryegrass emergence.  In our first experiment, we planted ryegrass at 0.5 inch deep and followed with no tillage (our control) or deep tillage. 

Our objectives were to determine the following:

1) Could deep turning effectively invert seed on the soil surface?

2) Could inverted seed placed 10-12 inches deep in the soil profile germinate?

Results showed a reduction in ryegrass emergence by over 99% with deep turning (figure/picture below).  Although this experiment does not address ryegrass seed spread throughout the soil profile as is the case in grower fields, it does suggest ryegrass emergence is greatly reduced when it is placed deep in the soil profile.  The next step is to better understand how long the seed will live when buried in our soils under our environmental conditions.  

Rarely will any cultural or mechanical practice effectively control ryegrass by itself.  Thus, an herbicide program will usually be needed.  See the wheat production guide or pest control handbook for herbicidal options.

Zidua Use in Wheat (Culpepper)

Zidua (pyroxasulfone), can be applied as a delayed preemergence or early postemergence application in wheat that is planted between 0.5 and 1.25 inch deep.  Zidua CANNOT BE APPLIED AS A TRUE PREEMERGENCE!

Delayed preemergence applications can occur when 80% of the germinated wheat seeds have a shoot at least ½ inch long up until spiking; applications of 0.7 to 1.0 oz/A (coarse soils) are appropriate for most Georgia fields while the rate can be increased to 1.25 oz/A on medium to fine soils.  Do not irrigate fields treated with a delayed preemergence application until wheat spiking and DO NOT apply delayed preemergence applications to broadcast-seeded wheat.

Early postemergence Zidua applications can be applied to wheat at spiking up to the fourth-tiller growth stage at a rate of 1.0 to 2.0 oz/A. 

Sequential applications may also be applied as long as the total use rate does not exceed 2.5 oz/A.

Ryegrass Control: If Zidua is activated prior to ryegrass emergence, excellent control is expected; however, if ryegrass is up at time of Zidua application then control of the emerged plants will likely be poor.  The label allows for mixtures with Axial which should control small emerged ryegrass plants that are not resistant to Axial.  Suppression of some broadleaf weeds will occur but control will not be good enough to replace broadleaf herbicide applications, especially for wild radish.

Crop Injury: Greatest potential for injury occurs when open/cracked seed furrow allows herbicides to directly contact the seed, when seed are planted to shallow, or when seed are planted in a deep furrow that allows herbicide concentration after a rain/irrigation event during wheat germination.  

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.

Excessive Injury with Liberty in WideStrike Cotton Currently Being Noted (Culpepper) - For Your Eyes Only

Early last week, I applied Liberty to WideStrike cotton throughout the state and I am now observing the highest level of injury that I have ever observed with Liberty in WideStrike cotton.  The increased level of injury is likely a response to our excessively moist environment.

Things to consider:

1. Try to avoid spraying Liberty on Widestrike cotton during our current extremely moist environment.  The best way to avoid the need for Liberty is overlapping residual herbicides as defined on the laminated handout you were given.  There are NO preemergence herbicide mixtures lasting longer than about 18 days and don’t forget you have to get the POST residual herbicide out and activated prior to the prememergence herbicide breaking.

2.  If spraying Liberty on WideStrike cotton, don’t overdo the rate.

3.  If spraying Liberty on WideStrike cotton, do not add any adjuvant.

4.  If spraying Liberty on WideStrike cotton avoid mixtures with Dual, Warrant or Staple at this current time.

5.  Remember neither Dow nor Bayer support the use of Liberty in WideStrike cotton.

6.  I would expect to return to normal injury levels once we are not swimming.

7.  No concerns spraying Liberty on GlyTol/LL cotton.

Reflex Issues in Vegetables (Culpepper) (For Your Eyes Only)

Agents, over the last couple of days we have had several serious mistakes made with Reflex in vegetables.  These mistakes are not related to UGA Extension and are not in accordance with the label. We must help our growers avoid these issues if possible. The objective of these labels is to provide new helpful weed management tools; however, these incidences could challenge our ability to continue using/developing third party labels (we have 28 now) such as Reflex in watermelon, squash, and/or pumpkin.

A few thoughts regarding current injury mistakes:

1.  Below is the newsletter I sent out a month or so ago; please review it once again.

2. Reflex will destroy most vegetables with ANY foliar contact; SO DON’T SPRAY IT OVERTOP (exception is snap bean, see 2014 UGA Pest Control Handbook).

3. Reflex can kill cucumber twice and can kill cantaloupe at least once regardless of application method; thus, there is no Reflex label for cucumber or cantaloupe and there will not be a label.  Therefore, make sure your growers understand that herbicides are not like many fungicides or insecticides that can be applied across crop groupings. 

4.  Please remind your growers about these labels and how these labels will help avoid serious issues.  Agents MUST NOT give growers any indemnified label.  Additionally, I would suggest agents not make any recommendation to a grower until that grower has printed and reviewed the label. 

----------------------------------------------------------------------------------------------------------------------------

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:

1.  Growers must have a label in hand when using Reflex in these crops.  These labels are written by myself 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 scientist 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 gaweed.com by March 12, 2014 or if you would like laminated copies for your growers, email me the number you would like 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.

8.  Print label and have present during application.

Warrant + Valor for Weed Control in Peanut (Prostko)

As I sit in my office watching yet another rain event (April 29), I am wondering why most GA growers seem to have a passion/obsession for using Warrant in every row crop possible.   It must have something to do with the Monsanto Rewards Program.  Anyway, I have been getting a lot of questions about mixing Warrant + Valor for PRE weed control in peanut.  Here are a few random thoughts:

1) The combination of Valor + Warrant is a perfectly legal/labeled option for GA peanut growers.

2)  Using Warrant PRE (except when planting later in May in fields with a history of tropical spiderwort/Benghal dayflower) in my opinion is a waste of its residual power.  There is not a lot of evidence in peanut to suggest that Warrant + Valor is significantly better on Palmer amaranth than Valor alone (i.e. assuming starting clean and rainfall/irrigation activation).

3) Warrant is not very effective on Texas panicum. That is why I always recommend either Prowl or Sonalan in combination with Valor.   You can probably count on 1 hand the number of fields in GA that do not have Texas panicum????? OK, there might actually be more than 5 fields???

4) I believe a better fit for Warrant in early planted peanut fields is to use it in combination with POST herbicides such as Gramoxone or Cadre.  However, the current Warrant label prohibits the use of Warrant on peanuts that are flowering.  A big mistake on Monsanto’s part which I hope will be corrected in the future.

5)  Early planted peanut fields are usually subject to cooler and wetter conditions which can lead to greater injury from PRE applied residual herbicides.   Although I have not yet observed this phenomenon in the field, Valor + Warrant or Dual could be more injurious to peanut than either applied alone in the wrong situation (low vigor/germ seed, improper planting depth, heavy rainfall, high rates, etc.).

6) As indicated in a previous blog, I have not observed any real differences between Warrant and Dual Magnum when used in a peanut weed management program.  As far as I am concerned at this point, flip a coin on these two!!!  FYI, Dual is more effective on yellow nutsedge than Warrant.

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.).

Atrazine-Resistant Palmer Amaranth Confirmed in Berrien County (Prostko and Vencill)

Plants from a recently collected Palmer amaranth seed sample, submitted by Berrien County Extension Agent Eddie Beasley, have been confirmed to be resistant to atrazine (Figure 1). This population was also resistant to glyphosate but not Staple (pyrithiobac).  The discovery of atrazine-resistance (AR) in Berrien County is potentially very important since this seed sample was collected from a row-crop production region (i.e. not a dairy production region).  As far as we can tell at this point, the field in question was continuous corn for at least 10 years.  This would suggest that the AR evolved via selection pressure rather than pollen flow or physical seed movement.  

There are a couple of positives here.  Firstly, 5 lbs/A of atrazine controlled these plants which would indicate that the level of resistance is low (2X) in comparison to what we have observed with glyphosate (6-8X).  Secondly, this population was controlled with Evik (ametryn), another member of the triazine herbicide family.  This confirms results from our previous research which suggested that AR in Georgia is metabolism based rather than target-site based.   

How do we plan to address this issue?  In 2013, Dr. Vencill and several County Extension Agents collected various weed seeds from numerous locations across Georgia (Figure 2). These weeds are now being screened for resistance to multiple herbicides, including atrazine. Also, we are planning to collect additional Palmer amaranth seed this summer in the major corn growing counties.  The plants grown from these seed samples will be screened by Dr. Vencill for resistance to atrazine.     

Although this recent discovery is alarming, we do not think that it necessarily means that AR is widespread.  Results from the above mentioned surveys will answer this question.  At this point in time, growers using normal crop rotations likely need not worry about AR.  Fortunately, numerous other herbicides can be used in field corn to effectively control Palmer amaranth (Armezon, Callisto, Capreno, Dual Magnum, Impact, Laudis, Liberty, Realm Q, Status, Warrant, and Zidua).   Refer to page 155 of the 2014 UGA Pest Control Handbook for specific recommendations regarding the control of GR-ALS-AR-Palmer amaranth in Georgia field corn (http://www.ent.uga.edu/pmh/Comm-Field-Corn.pdf).

Figure 1.  2013 Berrien County Palmer Amaranth Population Treated with 1, 2, and 5 lbs ai/A of Atrazine.

Figure 2.  2013 Herbicide-Resistant Weed Survey (Dr. Bill Vencill).

Liberty-Link Soybean Varieties (Prostko)

Growers searching for Liberty-Link (LL) soybeans varieties that perform well in Georgia may find that this list is rather short at this time.  This is typical for new technologies as varieties tend to get better as the technology becomes more widely adopted over time and space.  Just think back to the 1st generation of RR soybean varieties.  These early RR varieties were not the racehorses of today.  The chart listed below is a summary of the rankings for LL soybean varieties grown in the official 2013 UGA OVT tests (irrigated).

You will note that only 3 LL soybean varieties were ranked in the top 10 (yield) at 3 of 6 locations.  These include HBK LL4950 (indeterminate), HBK LL5350, and Halo 5:45.  Our recently hired UGA soybean breeder, Dr. Zenglu Li, is also incorporating the LL technology into his breeding program.  Thus, it is very likely that Georgia-bred LL varieties will be available in the near future.