2018 Dicamba Label Changes (Prostko and Culpepper)

Due to the recent concerns about off-target movement of dicamba, the EPA has mandated significant label changes for Engenia®, Fexapan™, and Xtendimax® for 2018.  Some of these important label changes are as follows:

1) Engenia®, Fexapan™, and Xtendimax® will now be considered Restricted Use Pesticides.

2) Growers who use Engenia®, Fexapan™, and Xtendimax® will be required to keep the following records for a period of 2 years, records must be generated within 14 days of application, and a record must be kept for every application:

a.     Certified Applicator Name

b.     Applicator Certification Number

c.     Product Name

d.     EPA registration Number

e.     Total Amount Applied

f.      Application Date

g.     Crop or site of application
h.   Location of application

i.       Size of area treated

j.       Training Requirement: Proof of auxin training

k.       Application timing: PRE or number of days after planting

l.       Receipts of Product Purchase

m.    Products Labels
n.   Buffer Requirement: record buffer distance calculation

o.    Sensitive Crop Awareness: Applicator must survey and document neighboring fields for sensitive areas or crops

p.     Spray Systems Cleanout:  Must be documented that applicator complied with label.

q.     Tank-Mix-Products: complete list of all approved products that were tank-mixed

r.     Application Start and Finish Times

s.      Nozzle Selection

t.      Air Temperature:  At boom height for start and finish

u.     Wind Speed/Direction: At boom height for start and finish

     

3) Fexapan™ and Xtendimax® minimum GPA changed to 15 gallons.
4) Can only be applied when wind is between 3 MPH and 10 MPH.
5) Can only be applied from sunrise until sunset.

Most growers will not be happy with these label changes.  However, failure to comply and/or increases in off-target movement of dicamba will likely result in the EPA’s cancellation of these products.  We will do our very best to keep you informed of any other significant changes. 

Weed Science Update - August 10 (Prostko)

A couple of reminders based upon my phone calls and e-mails over the last few days (click on Figures to view in larger format).

1) Revenge spraying large pigweed plants is not a viable option for growers who have been untimely due to rainfall or other circumstances (Figure 1).  Options for escaped weeds include hand-weeding or using a 50% solution of paraquat in a non-selective applicator (NSA) (Figure 2).  A NSA is more effective in peanut than soybean due to the height differential between the crop and weed (i.e. more of the weed gets treated in peanut).  Check out page 215 of 2017 UGA Pest Control Handbook for more information about the use of NSA in peanut.

2) Options for controlling Florida beggarweed in peanut at this time of year include a postemergence application of Classic, paraquat in a NSA, hand-weeding, or mowing.   Our data has shown that when grown under weed-free conditions, Classic can cause 7% to 11% yield reductions when applied to GA-06G.  Thus, growers who want to use Classic must weigh this potential yield loss against the negative effects that large beggarweed plants can have on fungicide deposition and harvest efficiency as the season progresses.  If beggarweed populations are dense enough to impede fungicide deposition and/or cause a digging nightmare, the use of Classic is justifiable.  Check out page 214 of 2017 UGA Pest Control Handbook for more information about the use of Classic in peanut.

3) Field corn producers with pigweed and tropical spiderwort/Benghal dayflower (TSW/BDF) problems need to seriously consider a post-harvest control strategy (Figure 3 and 4).  Post-harvest control programs for field corn are presented on page 86 of 2017 UGA Pest Control Handbook.  Post-harvest control programs for TSW/BDF are discussed on page 73 of 2017 UGA Pest Control Handbook.

What's Up This Week (Prostko)

A couple of interesting things to share with you this week:

1) Check out the following picture sent to me by Dr. Alan York (NCSU).  On day 1, Mr. Peanut Grower mixed 2,4-DB and dry manganese sulfate in 700-800 gallons of water with no problems.  On day 2, Mr. Peanut Grower mixed the same combo with only 100 gals of water and OH NO!!!!.  A great advertisement for pre-slurrying dry formulations prior to mixing in a big tank.

2)  Much ado in the the Mid-South about off-target movement of dicamba.  We have experienced a few problems in GA but nothing compared to what's going on there.  Just recently, I was asked how non-dicamba soybean yields could be affected by off-target movement of dicamba.  Although soybeans are very sensitive to dicamba and low rates will cause leaf cupping and epinasty, vapor drift rates (1/1000th X) and particle drift rates (1/100th X) will likely cause yield losses of < 9% depending upon the soybean stage of growth.

3) Current list of dicamba tolerances (i.e. how much residue in a crop is legal) can be obtained at the following web-site:

https://www.law.cornell.edu/cfr/text/40/180.227

Recent Tank-Mix Issues (Prostko)

Last week, I received a few calls and pictures from some folks about tank-mixes and peanut injury (Figures 1 and 2).  I will remind you that there is nobody on the planet that can assure any peanut grower that a tank-mix will be 100% safe and 100% effective all the time. There are too many variables to consider including the number of products in the spray tank, GPA, air temperature, humidity, leaf wetness, overall peanut plant health, and time of day.   I think part of the problem last week was our higher than normal temperatures (Figure 3).  A few tips for growers considering spraying untested tank-mixes:

a) Limit the number of products that are put in a spray tank.  Bite the bullet and make separate applications when practical.
b) Spray early in the morning when air temperatures are lower and the peanut plants have not been baking in the sun all day.
c) Increase water volumes from 10 GPA  to 15 GPA (less concentrated spray droplets).

Figure 1.  Peanut response to Convoy + Alto + Bifenthrin fb Select + COC
 1 hour later (i.e. really a 5 way tank-mix)

Figure 2.  Peanut response to Propulse + 2,4-DB (i.e. really a 3 way tank-mix)

Figure 3.  Maximum air temperatures, Attapulgus (GA), June 30 to July 7, 2015, 2016, 2017
(Source:  UGA Automated Weather Network)

Weed Science Update - June 16 (Prostko)

Just got done rating some of my soybean weed control plots.  Thought I would pass along these few thoughts.

1) Not sure what to say when someone asks me "When are you guys going to figure out how to control pigweed?"  I am pretty confident that we have but not everyone listens or can get it done! (Figure 1).

  

Figure 1.  General overview of 2017 soybean weed control plots in Ty Ty, GA.   Notice weedy-checks in comparison to other plots (started clean + activated residual + timely POST).

2) I fear that some are thinking that the new auxin technologies are the greatest thing since sliced bread.  That would be very stale sliced bread since 2,4-D has been around since the 1940's and dicamba since the 1960's.  I am still getting great results with other chemistries (Figure 2).

Figure 2.  Soybean weed control in 2017 with Tricor (metribuzin) followed by Roundup PowerMax (glyphosate)+ Reflex (fomesafen).

3) If growers decide that they must use the auxin weed control systems, I cannot over emphasize the need for residual herbicides in these programs (Figure 3).

Figure 3.  Weed regrowth/emergence (1 sq. ft.) 25 days after a single application of Roundup PowerMax (28 oz/A) + Xtendimax with VaporGrip (22 oz/A).

  

Valor Injury or The Sky Is Falling (Prostko)

My right ear is currently bleeding due to the numerous telephone calls that I have received over the last few days about Valor injury in peanuts.  Peanuts that were planted approximately 10 days ago or so were in a great place to get hammered from Valor because of the recent rainfall events (Figure 1).   Everyone seems to be panicking as though this was a surprise??????  If it rains on Valor treated peanuts when they are cracking and small (~2 weeks after cracking), injury will occur.  Peanuts typically recover from this injury without a yield penalty.  Check out Figures 2 and 3 from some of my research back in 2009.  In this trial, more than 5" of rainfall occurred in the 30 day period after peanut planting.  Peanut injury was significant but yields were not reduced even at a 2X rate.  Not sure what else I can say or do at this point???

Zidua Peanut Label (Prostko)

On Friday afternoon, May 19, I received word from BASF that Zidua (pyroxasulfone) was labeled for use in peanut.  I have been conducting peanut research with pyroxasulfone for more than 10 years (over 47 field trials).  In a nutshell (no pun intended), Zidua will compete with Dual Magnum or Warrant in our POST peanut herbicide programs for the residual control of Palmer amaranth and a few other weeds (Figure 1). Some advantages for Zidua include its lower use rate (1.5 oz/A-2.1 oz/A) and improved control of other broadleaf weeds such as Florida beggarweed.  Generally, I have observed no real differences in performance/yield between Zidua, Dual Magnum, and Warrant when used in a complete peanut weed control program (Table 1). A copy of the supplmental peanut label can be obtained at the following web-address: http://www.cdms.net/ldat/ldAMK017.pdf

Figure 1.  Zidua vs. Dual Magnum Programs in Peanut - 2016.

Table 1.  Dual Magnum/Warrant/Zidua Peanut Weed Control Programs - 2014.