Bermudagrass Burndowns (Prostko)

     During the last few weeks, I have received a few inquiries about controlling bermudagrass prior to planting various row crops.  An established stand of bermudagrass can be very difficult to manage.  When dealing with bermudagrass burndowns, glyphosate rate and time of application are crucial.  Here are a few points to consider:

1) When applying glyphosate in the spring, when is the best time of application?  Generally, later applications are more effective after the bermudagrass has greened up and is actively growing (Figure 1).

  
2) Can bermudagrass be effectively controlled with 1 application of glyphosate?  What rate of glyphosate should be used?  In previous UGA research, the most effective control of bermudagrass occurred when 3 applications of glyphosate @ 2 lb ai/A were applied (Figure 2).  Obviously, this program would have to be implemented the year before planting a spring row crop.  I hope you notice that a single application of 4 lb ai/A of glyphosate applied in May was not very effective (38% control).

3) Growers who are relying on spring applications of glyphosate only will almost certainly have to follow up in-crop with 1 or 2 applications of a postemergence grass herbicide, such as Select or Poast (only in labeled broadleaf crops), or glyphosate (only in labeled GR-crops).  Consequently, those extra herbicide costs should be included in their budget plans.  Additionally, it might take a few years of fighting before optimum bermudagrass control will be obtained.

Future Paraquat Changes (Prostko)

Paraquat is the active ingredient in several popular herbicide formulations used in Georgia (Firestorm, Gramoxone, Helmquat, and Parazone).  It has multiple uses including preplant burndown applications, early-postemergence weed control in peanut, and as a soybean harvest-aid.  Paraquat registration has been under review by the EPA and many changes will be occurring in the very near future.  The main reason for these changes is that many people have died over the years from ingesting paraquat that was improperly stored in various types of containers (cans, plastic bottles, cups, etc.)   The following table of future changes was provided to me by Syngenta (the purveyors of Gramoxone) and these dates are subject to change:  

Cold Temperatures and Herbicides (Prostko)

     Growers who have sprayed certain POST systemic herbicides (i.e. Roundup, Poast, Select) over the last 15 days are likely to observe slower and/or reduced performance due to the cold weather.  When temperatures drop below 50 F, weird things start to happen because plant growth is stalled and physiological processes such as absorption and translocation are reduced.  In the past 15 days, most areas in Georgia had 10-11 days of temperatures below freezing (Figure 1).  Those temperatures are not very herbicide friendly.  Daily low temperatures are expected to be below freezing through Saturday night (Jan 20).  Growers with ants in their pants might want to wait until Sunday or later to resume any herbicide spraying that is needed. If a grower has already made an herbicide application during this cold snap, I would suggest that he/she evaluate the situation 10-14 days after treatment and re-treat if needed and if the label permits.

Chart Source:  UGA Environmental Network, accessed 01/16/18

Weed Control in Field Pea (Prostko)

      In some areas of our state, the poultry industry is encouraging growers to plant winter field peas for use as chicken feed.  Unfortunately, the UGA Weed Science Group has limited (i.e. no data) on herbicide use in this crop.  I have put together the following table of herbicides that are labeled for use in field pea.  However, there is no UGA research data supporting crop tolerance and/or weed efficacy.   My research counterparts are in the process of setting up field trials right now in Plains and Athens.  Will let you know how they turn out. (click on chart to make it larger).  

     Other herbicides such as Valor (flumioxazin) or Tricor (metribuzin) are registered for field pea use in other states but not in Georgia.  Since these are not labeled and we have no supporting data, it would not be a good idea use these!!!!

Weed Science Update - November 2017 (Prostko)

Just a few weed science items that I thought you might find of interest.  Some may be new or old news?

1) Enlist One, from Dow Agrosciences, is a new 2,4-D choline formulation registered for use on Enlist crops (2,4-D tolerant).  As you may recall, Enlist Duo is a pre-mixture of glyphosate + 2,4-D choline.  According to my secret sources, Enlist cotton varieties were planted on ~2% of the acreage in Georgia.  A copy of the Enlist One label can be viewed or downloaded from the following location:  http://www.cdms.net/ldat/ldE27000.pdf.  I am not  sure yet what the final shakeout is with the Dow/Dupont merger.

2) FMC has acquired the following herbicides from DuPont: Affinity, Agility, Ally, Express, Finesse, FirstShot, Glean, Harmony, Harmony Extra, Panoflex, Sentrallas, Upbeet.

3) Agrium/Crop Production Services (CPS) has acquired 20 Southern States locations in Georgia and Florida.

4) BASF is buying Bayer's seed business (canola, cotton, soybean) and Liberty-Link business.

5) If interested, final results from my 2017 weed control field trials can be found at the following location:  http://gaweed.com/reports.html

6) Annual UGA Weed Science Update for county extension agents is on December 6 in Tifton.  Tentative agenda is as follows:

2017 UGA Weed Science Update Agenda

Date: December 6, 2017

Location:  Tifton Campus Conference Center (RDC)

Times: 9:15 am - 3:30 pm

Agenda

9:15-9:30 am                             Light refreshments

9:30-10:00 am                           Peanut (Prostko)

10:00-11:00 am                         Using Pesticides Wisely – Agent Responsibilities and Update (Culpepper)

11:00-11:30 am                          Field Corn (Prostko)

11:30-12:00 pm                         Cotton (Culpepper)

12:00-12:30 pm                         Lunch on site

12:30-1:00 pm                           Nozzle Demonstrations (Carter)

1:00 -1:30 pm                            Soybeans (Prostko)

1:30- 2:00 pm                            Small Grains (Culpepper)

2:00-2:15 pm                             Break

2:15-2:45 pm                             Miscellaneous Crops (grain sorghum, sunflower) (Prostko)

2:45 pm – 3:30 pm                    Vegetables (Culpepper)

3:30 pm                                     Program Evaluation/Adjourn

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.