Engenia™ Label Approved (Prostko)

I just received word that BASF's low volatility formulation of dicamba (Engenia™) was approved for use on dicamba-tolerant (DT) cotton and soybean.  You may recall that Monsanto's Xtendimax™ with Vapor Grip™  was registered back in November 2016.  It is important to remember that Engenia™ and Xtendimax™ are not the same formulation and that their labels are slightly different.  I have tried to succinctly summarize their differences in Table 1.  A copy of the supplemental Engenia™ labels can be accessed from the following locations:  soybean  cotton  

Table 1.  Engenia™ vs Xtendimax™.

	Engenia™	Xtendimax™ with Vapor Grip™
dicamba formulation	BAPMA	DGA
dicamba lbs ae/gal	5.0	2.9
Single POST In-Crop Application Rate/A	12.8 oz	22.0 oz
Total POST  In-Crop Rates/A (2 apps)	25.6 oz	44.0 oz
Total Season Rates/A	51.2 oz	88.0 ozs
Time of Application	PPLNT/PRE/POST (R1)	PPLNT/PRE/POST (R1)
Tractor Speed	< 15 MPH	< 15 MPH
Boom Height	24” or less	24” or less
Nozzles	Turbo TeeJet® TTI11004	Turbo TeeJet® TTI11004
Wind Speed	0-3 MPH = confirm temperature inversion 3-10 MPH = optimum 10-15 MPH = do not apply if wind blowing towards sensitive crops > 15 MPH = do not apply	0-3 MPH = do not apply 3-10 MPH = optimum 10-15 MPH = do not apply if wind blowing towards sensitive crops > 15 MPH = do not apply
GPA	10+	10+
Buffers	110 ft	110 ft = 22 oz/A; 220 ft = 44 oz/A
Tank-Mixes	NO herbicides; NO AMS or UAN www.engeniatankmix.com	NO herbicides; NO AMS or UAN www.xtendimaxapplicationrequirements.com

There is also likely to be another low volatility formulation of dicamba from Dupont® sold as FeXapan™ plus Vapor Grip™. I will let you know when that one gets labeled.  Georgia will issue 24-C labels for these new dicamba formulations which may have additional requirements.  

Liquid "Valors" (Flumioxazin) - Prostko

     In 2017, there will be 2 liquid formulations of flumioxazin available for use.  These include Valor EZ (Valent) and Panther SC (NuFarm).  As far as I know, they are the same stuff in a different bottle (4 lbs ai/gal)!  I am still a bit confused on how these will be marketed since it is likely that that Valor SX 51WG (dry) could be cheaper.  Also, it is very unlikely that Culpepper and I will officially recommend these liquid formulations in Georgia since we have almost no efficacy and/or crop tolerance data.  Earlier today, I did some bottle tests with the local Valent folks (John Altom and Hunt Sanders) to see if there might be any potential tank-mixing problems with the new liquid formulation. A few key observations:

1) When compared to the dry formulation, the liquid formulation disperses more quickly and evenly when mixed with water (Figure 1).

2) However, mixing order is extremely important.  The liquid formulations must be added to the tank first before mixing other chemicals.  If other tank-mix partners, such as glyphosate or paraquat, are put into the tank before the liquid flumioxazin, it is very likely that a nozzle/screen clogging precipitate could occur (Figure 2).

3) Agressive tank-agitation will continue to be very important when using liquid formulations of flumioxazin.  

Figure 1.  The equivalent of 3 oz/A in 15 GPA (Panther 4SC - left; Valor SX 51WDG - right) approximately 10 seconds after adding to the bottle (no agitation or shaking).

Figure 2.  NIS (0.25% v/v) followed by Gramoxone 2SL (48 oz/A) followed by Panther 4SC (3 oz/A) after agitation/shaking (rates equivalent for 15 GPA). Notice white precipitates floating around. 

Zest™ Approved for Use in Inzen™ Grain Sorghum (Prostko)

I just received word that Zest™ 75WDG (nicosulfuron) has received Georgia approval for use on Inzen™ herbicide-tolerant grain sorghum varieties.  Grain sorghum growers who use this technology will now be able to get better POST control of Texas panicum and other grasses.  I have discussed Zest/Inzen in a previous UGA Weed Science Blog (February 15, 2016) and in our December agent training meetings. Nicosulfuron is the same active ingredient in Accent, which is registered for use on field corn.

A couple of reminders:

1) Zest can only be used on Inzen herbicide-tolerant grain sorghum varieties. The use of Zest on conventional sorghum varieties will result in crop death! Inzen grain sorghum varieties are not GMO's.

2) The current formulation of Zest is a WDG.  I have been testing a liquid formulation so rates would be different in any slides you have previously seen from me.

3) UGA has limited variety performance data (i.e. none).  As far as I know, the only company with Inzen varieties is Advanta/Alta (http://altaseeds.advantaus.com).  Pioneer will likely have some varieties in 2018 or 2019?  Thus, I would suggest Georgia sorghum growers proceed with caution until an adapted variety is identified.  I have not been overly impressed with the varieties that I have been testing up until now.

4) I would still recommend the use of Concep treated seed + a PRE application of Dual or Warrant in this system.  Atrazine should be tank-mixed with Zest to improve the control of broadleaf weeds.

5) A copy of the complete Zest label can be accessed from the following location:
http://www.cdms.net/ldat/ldDEH000.pdf

Dicamba Labels Approved (Prostko)

Yesterday, the EPA approved the first labels of dicamba for use on on dicamba-tolerant cotton and soybeans. A few interesting highlights from the labels include the following:

1) Xtendimax™ with VaporGrip™ Technology can ONLY be tank-mixed with products that have been tested and found not to adversely affect off-site movement potential.  A list of those products can be found at www.xtendimaxapplicationrequirements.com (This site was not yet available for viewing as of 9:24 am today).

2) Only 1 nozzle type is permitted (TTI11004 with 63 PSI max)

3) Must be applied in a minimum of 10 GPA

4) Maximum ground speed is 15 MPH

5) Maximum boom height of 24" above target pest or crop canopy

6) Can only be applied when winds are between 3 MPH and 15 MPH (3 MPH to 10 MPH is optimum).

7) Must maintain a 110 to 220 foot downwind buffer, depending upon rate, between the last treated row and the closest downwind field edge.

8) A copy of the cotton label can be viewed at the following location:

https://www.regulations.gov/document?D=EPA-HQ-OPP-2016-0187-0958

If you are not familiar with VaporGrip™ technology, refer to the following YouTube video:

https://www.youtube.com/watch?v=IWW4scEgpuU

More specific and up-to-date information will be presented at the UGA Weed Science Agent Update on December 7.

Using Pesticides Wisely - 2017 Classroom Trainings (Culpepper)

We are currently planning a final round of trainings for our Using Pesticides Wisely training during February/March of 2017 and would request your input on potential locations.  Our goal continues to be making it as easy as possible for attendance.   To date, we have conducted the training 26 times in Georgia as noted below.  Please e-mail Culpepper at stanley@uga.edu to give us feedback on where we have growers that we have missed and your thoughts on potential locations by November 1, 2016.  A few other thoughts about this training:

*Remember if auxin technologies do get labeled, which is currently unknown, licensed applicators responsible for in-crop applications of dicamba or 2,4-D, in respective technologies, will be required to take this training.

*Our estimates suggest we have trained at least 85% of the growers that would want to use these technologies.

*The small number of people left to train should easily fit in county offices, so our locations will be at Agent facilities if agents are supportive.

*Anticipating 2 or 3 final locations for South Georgia and 2 locations for North GA?

Off-Label Dicamba Use (Prostko)

     In case you have not heard, there have been numerous problems in certain states, such as Missouri and Arkansas, with off-label applications of dicamba on dicamba-resistant crops.  In Arkansas, things have gotten so out of hand that the Arkansas State Plant Board is proposing numerous restrictions on the use of dicamba in their state.  Some of these potential restrictions include the following:

1) Banning the use of dimethylamine (DMA) salt and acid formulations (i.e. Banvel), except on pastures/rangeland but only if all susceptible crops are at least 1 mile away in all directions.

2) Prohibiting the application of dicamba diglycolamine (DGA) salt and sodium salt formulations (i.e. Clarity) from April 15 through September 15 (except on pastures/rangeland with the 1 mile susceptible crop buffer).

3) When BASF's Engenia formulation (dicamba-BAPMA) is used, a 1/4 mile downward buffer zone and 100' buffer zone in all other directions will be required.  Engenia is less volatile than Banvel or Clarity.

4) New certification training will be required for both the Enlist (2,4-D) and Xtend (dicamba) technologies.  As you already know, we (UGA Extension) have been doing this type of training for 2 years.  

     These restrictions are not final with a 30 day comment period and public hearing scheduled for November 21.  Ultimately, the Governor and state legislature in Arkansas will have the final say.

     As far as I know, Georgia growers have done a good job of not abusing dicamba this year and there has been no talk of restrictions such as those listed above in our state. However, what's going on in Arkansas should serve as a reminder to any Georgia grower or chemical dealer of the potential consequences of off-label uses or violations.  Since Georgia is a large producer of potentially sensitive speciality crops, it will be important for all of us involved in this situation to do the right things and use common sense!!!

Weed Update - August 19, 2016 (Prostko)

It has been a while since my last blog.  In the last 60 days, I was out of commission for at least 27 days for various reasons (vacation time, 3 professional meetings, and 2 college moves).   However, the telephone calls kept rolling in!  Here are a few things to consider based upon recent calls:

1) Glyphosate will not adequately control sicklepod plants that have emerged thru the top of a soybean canopy.  However, glyphosate might have some effect on seed rain depending upon the sicklepod stage of growth at application and how much of the plant actually gets treated (Figure 1).  However, I would not expect as much seed reduction as depicted in this graph if only a few inches of the sicklepod plant actually gets treated with glyphosate. 

Figure 1.  Late-season response of sicklepod to glyphosate @ 0.75 ai ae/A as influenced by application timing.

2) Growers who have planted ultra-late soybeans need to be more conscious of herbicide crop rotation restrictions.  For example, Reflex, Prefix, or Warrant Ultra all have a field corn rotation restriction of 10 months (yes, this is real!!).  Thus, these herbicides should be avoided if field corn will be planted early next spring.  POST soybean herbicides with minimal crop rotation restrictions include Liberty, Cobra, or Ultra Blazer.  

3) At this time of year, there are NO miracle cures or magical silver bullets for escaped morninglory, Texas panicum, or sicklepod in any crop.  Growers will need to rely on harvest aids or non-selective applicators when appropriate and/or labeled.  What's the best strategy for controlling a 12-24" weed?  Treating it when its 3" tall!!!!!!!!!!!!!!  Sometimes a difficult but necessary pill to swallow.

4) Growers need to stay vigilant in their post-harvest (corn) weed control efforts to minimize weed seed-rain back into production fields.  It would only take a few escaped, seed-producing plants to mess up multiple years of good weed control.  Please refer to pages 74 and 87 of the 2016 UGA Pest Control Handbook for more information about post-harvest weed control strategies.

5) As a reminder, I would be more than happy to spend some time in any county at this time of year at your request!  

Weed Science Update - Week of July 4, 2016

1) This is what an IPhone 6 + LifeProof case looks like after mowing with a Massey Ferguson 2615 (50 HP) + 6' rotary mower.  I have a new phone now so please feel free to call me as usual.  

2) Earlier this week, I had some questions about peanut fungicide tank-mixes with Cobra and Strongarm.  Here is what I know based upon some older data (not much though):

a) Cobra + Fungicides:  Results from a field trial conducted in 2005 suggested no problems with Cobra + Bravo or Folicur.  When Abound was tank-mixed with Cobra, Florida beggarweed control was reduced by 12%. When Headline was tank-mixed with Cobra, annual morningglory control was reduced by 8%. All treatments also included COC @ 1% v/v. Peanut injury was not increased with Cobra + fungicide tank-mixtures. All treatments were applied to Georgia Green at 28 DAP.   

b) Strongarm + Fungicides:  From another field trial conducted in 2005, annual morningglory control was not reduced when Strongarm was tank-mixed with Bravo WS, Abound, Folicur, and Headline.  Florida beggarweed control with POST applications of Strongarm was poor in general (<70%) and control was further reduced by 15% when tank-mixed with Headline.  NIS @ 0.25% v/v was included with all treatments.  Peanut injury was not increased with Strongarm + fungicide tank-mixtures.  All treatments were applied to Georgia Green at 23 DAP.

3) Someone asked me about the tolerance of soybeans to dicamba drift.  As with most drift situations, it all depends upon rate and stage of growth.  Generally, soybeans are less tolerant of dicamba drift at reproductive stages of growth.  

Peanut Tank-Mix Time (Prostko)

Now is the time of year that most of us will get numerous questions about the various tank-mixes that peanut growers would like to try.  Here are a few reminders:

1) With over 90,000 potential peanut tank-mixtures, it is impossible for UGA or anyone else to have all the answers.  If a  grower puts more than 2 chemicals in a spray tank, it is very likely that that specific mixture will not have been adequately tested.

2) Just because a specific tank-mixture may not have caused peanut injury on one day, it does not mean it will not cause injury at another time.  Peanut response to tank-mixtures is a function of many factors including temperature, humidity, leaf wetness, and overall plant health.

2) The following is a good publication to keep handy at this time:  Tank-Mixing Chemicals Applied to Peanut Crops: Are the Chemicals Compatible?.  This publication can be accessed from the web at the following location:

http://www.peanut.ncsu.edu/pdffiles/004993/tank_mixing_chemicals_applied_to_peanut_crops.pdf

3) 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)

4) Here a few slides of some tank-mixtures that I have tried or seen in the field.

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Peanut Tips - Week of May 23 (Prostko)

A few comments based upon some frequent questions that I have received this week:

1) Generally, there should be no major problems mixing Orthene (acephate) with paraquat cracking treatments (Peanut Science 2014 41:58-64).

2) UPI is in a sold out position for Storm 4SL herbicide.  However, Storm is in UPI's production schedule for next year.  No worries though since growers can make their own Storm if need be.  1.5 pt/A of Storm would be equivalent to 1 pt/A of Ultra Blazer 2SL +  1 pt/A of Basagran 4SL.  FYI, when making your own Storm cocktail for mixing with paraquat, I prefer 1 pt/A of Ultra Blazer + 0.5 pt/A of Basagran.  0.5 pt/A of Basagran still helps "safen" the peanuts but this new ratio will be slightly more active on the weeds.  

3) Helena has been actively promoting a product called ENC (Ele-Max Nutrient Concentrate) to be used in combination with paraquat cracking sprays.  According to Helena, the use of ENC will help the peanuts recover faster from paraquat injury.  As far as I can tell, ENC is a fertilizer solution (11-8-5 + various micros).  We are currently evaluating this product and its potential benefits.  Preliminary results from 1 trial in Attapulgus this year would suggest that the use of ENC resulted in less peanut injury (leaf burn) at 3 DAT (Figure 1) but no differences were detected at 7 DAT (Figure 2).  Way too early for a yea or nay recommendation at this point!!!  More to follow as additional data is collected.  

Figure 1.  Influence of ENC on peanut leaf burn - 3 DAT - 2016.

Figure 2.   Influence of ENC on peanut leaf burn - 7 DAT - 2016.

4) Guess what?  When it rains on peanuts that were treated with Valor, especially at cracking, you get crop injury.  It happens all the time, regardless if they were irrigated immediately after application or not.  Unless something funky has happened (i.e. sprayer problems, excessive rates, misapplication, etc.), research results and on-farm experiences since 2001 would suggest that is very likely that the peanut plants will recover from Valor injury with no yield loss.  For more info and injury pictures, refer to my June 3, 2013 blog on this very same issue.

Liquid Flumioxazin Mixing Problems (Prostko)

Panther 4SC (NuFarm) is a new liquid formulation of the active ingredient flumioxazin (i.e. Valor). This week, I have heard a few complaints about some tank-mixes with this new formulation. Growers who use this liquid formulation must follow the mixing order described below in order to minimize potential tank-mix problems:

Check out the following YouTube video for some cool visuals about Panther 4SC.  FYI, I have not sprayed a single drop of Panther 4SC so I have no experience or data at this point with this new formulation.

https://www.youtube.com/watch?v=PvpsOI7C50M

Metribuzin on Soybeans (Prostko)

As many of you know, I have been trying my very best to prevent the overuse of Valor and Reflex in soybeans, especially for growers who also plant cotton and peanuts.  Growers who want to protect Valor and Reflex (PPO's) have many other PRE options including Dual, Warrant, and metribuzin.  For you Roundup babies out there, let me remind you of a few things about metribuzin.

1) Metribuzin used to be sold under the trade names of Sencor (Bayer) or Lexone (DuPont).  Many moons ago, about 20% of the US soybean crop was treated with metribuzin.  

2) Current trade names for metribuzin include the following: Tricor, Metribuzin, Dimetric.

3) Metribuzin is also a component of many soybean pre-mixes including the following: Authority MTZ (metribuzin + Spartan), Boundary (metribuzin + Dual Magnum), Canopy or Canopy Blend (metribuzin + Classic) ), Intimidator (metribuzin + Reflex + Dual Magnum), and Trivence (metribuzin + Valor + Classic). 

4) When using metribuzin in soybeans, soil type, OM and pH are very important.  Metribuzin should not be used on coarse soils (i.e. sandy loam or loamy sand) with less than 1% OM and/or in soils with a pH greater than 7.5.  Refer to the individual product labels for more specific information about use rates, soil types, and organic matter restrictions.

5) Metribuzin should not be used on sensitive soybean varieties.  Check out page 268 of the 2016 UGA Pest Control Handbook for a partial list of soybean varieties that have been screened for tolerance.  Also, check out the following publication from the University of Arkansas ( http://mssoy.org/wp-content/uploads/2014/12/2014-SOYBEAN-VARIETY-METRIBUZIN-SCREENING-UA1.pdf).  

6) Metribuzin is in the same herbicide family as atrazine (triazine). Metribuzin is a PS II inhibitor (WSSA Group 5).

7) Metribuzin injury symptoms on soybeans are presented in Figures 3 and 4.  

Figure 3.  Metribuzin injury on soybeans.

Figure 4.  Metribuzin injury on soybeans.

Prowl vs. Sonalan in Peanuts (Prostko)

Recent price increases in Sonalan 3EC (ethalfluralin) have many growers taking a closer look at the cheaper priced pendimethalin formulations (Generic Prowl 3.3EC and Prowl H2O 3.8ASC) for use in peanuts.  With the exception of use in reduced tillage systems (i.e. Prowl is preferred there), there have been no consistent differences in peanut tolerance and weed efficacy between Sonalan and Prowl in peanut (Table 1).  It has always been my position that I have no preference between these two herbicides and that every peanut acre in Georgia should be treated with one of them.  If a grower is trying to save a few bucks on input costs, there is no reason not to use a cheaper formulation.

A couple of other comments about this issue:

1) The Weed Science Group at UGA has not been able to detect any major differences in the performance between Prowl 3.3EC and Prowl H20 3.8ASC.
2) 2016 estimated costs for 1 qt/A are as follows:  Sonalan 3EC = $10.50; Generic Prowl 3.3EC = $6.75; and Prowl H2O 3.8ASC = $8.75.
3) The lb ai/A for each formulation are slightly different at the 1 qt/A typical use rate as follows:  Sonalan 3EC = 0.75 lb ai/A; Generic Prowl 3.3EC = 0.83 lb ai/A; and Prowl H2O 3.8ASC = 0.95 lb ai/A.  This might need to be considered when figuring the true cost differences per acre.  

Indemnified Label Allows Dual Magnum Overtop of Summer Squash – Yellow and Zucchini (Culpepper)

Our new label allowing Dual Magnum over-the-top of emerged seeded and transplant squash grown on bare-ground or in a mulch system has been approved for use in Georgia.  The label should be self-explanatory….if not let me know as I was one of the authors.  

Getting Label: See steps below on obtaining the label (this information has been provided several times).

Grower Must Obtain His/her Label: For years we have stressed the importance of growers having a copy of our state local need (SLN) indemnified labels when making applications. This is getting more serious as the Department of Agriculture has started asking to see these labels doing routine visits; this is simply a response to the sheer volume of state local need labels we now have for Georgia growers.  To drive the point home here is an e-mail from GDA a few weeks ago “Dr. Culpepper, If you talk to any grower groups regarding any SLN approvals, please remind them that they must keep or present the SLN label for our inspectors during an audit or it is a label violation. Our inspectors find many individuals that cannot produce an SLN label during farm inspections.”

Thanks,

Eric Olsen

GDA”

OBTAINING LABELS FOR DUAL MAGNUM OR REFLEX:

Consider helping your growers by asking them to come in and visit with you to get their label. This is a great opportunity for young/new agents to obtain face time with our clientele!!

Agents MUST NOT give growers any indemnified label or make any verbal recommendations until the grower has the label.  Agents can help growers through the process but must make sure the grower clicks the “I ACCEPT” liability waver when obtaining the label.

Obtaining the label for First Time (first time takes a couple minutes, thereafter very simple):

1.  Go to www.farmassist.com

2.  Register the grower (or if you want a label register yourself); “register” is located on the 2nd tool bar in top middle of page.  After filling in information; click I accept at bottom.

3.  The next page that pops up asks about you; you do not have to fill this out if you do not want.

4.  Select products along top bar.

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

6.  For state, select Georgia and for product, select Dual Magnum or Reflex (play around and see our other labels) and then submit.

7.  Select the Dual Magnum or Reflex crop of interest and submit.

8.  Accept waiver; this is the process making the label an indemnified label.  GROWER MUST CLICK THE  I ACCEPT KEY TO GET THEIR LABEL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

9.  Print label and have present during application.

Sweet Potatoes and Cadre (Culpepper and Prostko)

Over the last several years, many county agents have asked about carryover concerns of Cadre applied in a peanut crop to sweet potato the following season.  The Cadre label restricts planting potatoes to 40 months after a Cadre application but the label does not specifically mention sweet potato.  Many have wondered is it really this serious?

According to the 2014 edition of the WSSA's Herbicide Handbook (page 256), the half-life of Cadre or the time in which about half of the Cadre would be gone is approximately 120 days.  In theory then, a June application of Cadre at 4 oz/A in peanut should be down to a rate somewhere between ½-1 oz/A approximately 8-12 months later when one would plant sweet potato.  

During 2015, a study was conducted where we applied ½ and 1 oz/A of Cadre prior to transplanting sweet potato.  Cadre at ½ oz/A caused 55% visual injury (stunting and discoloration) and reduced U.S. Number 1 fruit yield by 59%.  For Cadre at 1 oz/A, sweet potato injury reached 77% and reduced U.S. Number 1 fruit by 96%.  Simply, applications of Cadre in peanut should be avoided if you plan to rotate to sweet potato!!!!!.

Quick Responses (Prostko)

Here are a few answers to some questions that I have been receiving over the last few weeks or so:

1) How long do I have to wait to plant field corn if I use 1 pt/A of 2,4-D amine in my pre-plant burndown?

I usually recommend that growers wait at least 7-10 days after an application of 2,4-D amine to plant field corn.  If they need to plant sooner than that, the 2,4-D should be replaced with atrazine (1 qt/A).  When atrazine is used in a pre-plant burndown, field corn can be planted immediately.  However, I would still prefer planting into dead stuff. 

2) How long do I have to wait to plant peanuts if I use 1 pt/A of 2,4-D amine in my pre-plant burndown.

UGA research has shown that peanut planting can occur 7 days after an application of 2,4-D amine.

3) When tank-mixing glyphosate with atrazine or other herbicides for POST applications in field corn, is an adjuvant still needed?

If the formulation of glyphosate is "loaded" (i.e. already contains surfactants) then additional adjuvants (NIS or COC) are not really needed and may increase potential crop injury. Rather than re-invent the wheel, my weed science colleagues at Penn State University have put together an up-to-date list of the different formulations of glyphosate.  Check out the following link:

http://extension.psu.edu/agronomy-guide/pm/tables/table-2-4-1a

Ammonium sulfate (AMS) should always be used with any glyphosate treatment in situations where hard water (higher amounts of Ca, K, Mg, Na, etc.) is a problem.  The AMS must be added to the spray tank before the glyphosate.

4) What are some potential causes of "white" or off-color field corn seedlings?

a) stress inhibiting chlorophyll accumulation (i.e. compaction, cold temperatures)
b) low temperature sunscald & cold banding (cool, clear dewy nights followed by sunny mornings)
c) genetics
d) herbicide injury (Halex GT, Capreno, Laudis, glyphosate, others?)

5) What is the potential for Strongarm carryover in field corn in Georgia?

a) The labeled rotation restriction for field corn is 18 months.
b) Research and experience over the past 17 years would suggest that the risk of Strongarm carryover (irrigated fields only) would be low.  However, I will never say never! It would not be a good idea to plant field corn in a dryland field where Strongarm was used in peanuts the previous year!
c) If you suspect herbicide carryover in early-season field corn, I would strongly suggest that you collect both a soil pH and nematode sample because both of these problems are much more common than herbicide carryover.  Soil pH and nematode problems cause corn injury symptoms that look very similar to herbicide injury.

A Hose is a Hose? (Prostko)

Despite 15 years of on-farm use, I continue to receive frequent questions at winter grower meetings about cleaning sprayers of Valor residues.  The Valor label has very specific instructions about the correct method for sprayer clean-out.  These instructions are very labor/time intensive thus I am not sure if growers are willing to follow all the required steps, especially when in a hurry? Check out the June 3, 2013 UGA Weed Science Blog for the labeled instructions.  Valent also sells their own tank cleaner, creatively named Valent Tank Cleaner, to help with this problem.  Since the degree of tank-cleaning success seems to vary by grower, it might just be more of an art than science?

If you have a grower that continues to struggle with Valor clean-out issues, you might want to find out what kind of hoses are on the sprayer.  Although naked to the human eye, rubber hoses, especially older ones, often have cracks and crevices that can trap Valor residues which can then be released at a later date (Figures 1 and 2).  Valor-challenged growers might want to consider replacing older rubber hoses with new polyethylene hoses. Although they can be more expensive (~$3/ft), there is some evidence to suggest that this type of hose is less likely to hold on to herbicide residues.    

Figure 1.  Scanning electron micrograph of a brand new Goodyear rubber spray hose (black, Versigard, synthetic).  Photo courtesy of Drs. Gary Cundiff and Dan Reynolds, Mississippi State University, 2016. 

Figure 2.  Scanning electron micrograph of Goodyear rubber spray hose (black, Versigard, synthetic) used 8 times.  Photo courtesy of Drs. Gary Cundiff and Dan Reynolds, Mississippi State University, 2016.