Postemergence Field Corn Herbicides (Prostko)

Not sure what happened, but the table below was accidently left out of the 2013 UGA Pest Control Handbook.  It should help you address questions about times of application in field corn.

 

Table 1.  Times of Application/PHI for Postemergence Herbicide Labeled for Use in Field.
 

Herbicide	Field Corn Stage of Growth		PHI (DAYS)	Grazing, Feed, Forage, Hay, Silage Interval (days)
	Earliest	Latest
Accent Q	1-2 leaf	20” or V6 20-36” or V10 - drops		30
Aim	spike	V8 V8-14 leaf collars - drops	14 leaf collars	14
Atrazine	PPI/PRE	12”		grazing = 21 forage = 60
Basagran	1-2 leaf	NL		12
Callisto	pre	30” tall or 8 leaf stage	45	45
Capreno	V1	V6 V6-V7- drops		45
Clarity	1-2 leaf	5th leaf or 8” tall 8-36” tall drops
Dual Magnum	PPI/PRE	40” tall		30
ET	Spike	V4 V4-V8 - drops	90	50
Halex GT	Spike	30” or V8	45	45
Impact/Armezon	spike	??	45	45
Laudis	1-2 leaf	V8		45
Liberty	spike	24” or V7 24-36” - drops	70	60
Prowl H20	spike	30” or V8		21
Realm Q	1-2 leaf	20” or V7	70	45
Resolve Q	1-2 leaf	20” or V7		30
Roundup	spike	30” or V8 30-48” - drops	50	50
Sandea/Permit	spike	layby		30
Status	V2	5th leaf or 8” 8-36” or V10 - drops	72	32
Steadfast Q	1-2 leaf	20” or V6		30
Warrant	spike	24” 24-30” - drops		40
Zidua	spike	V4

¹NL = none specifically listed on the label. 

 

Valor Application Method (Prostko)

Not sure what's going on in some counties so here is a friendly reminder that UGA does not recommend that Valor be applied preplant incorporated (PPI) in peanut for 2 very good reasons: 1) Valor is not labeled for this type of application and 2) PPI applications provide significantly less control of of Palmer amaranth than PRE applications (Figure 1).

Gramoxone/Reflex Tank-Mixtures (Prostko)

Over the last few years, growers have experienced a few problems when tank-mixing Gramoxone (paraquat) + Reflex (fomesafen).  In order to prevent these potential compatibility problems, consider the following recommendations developed by Syngenta:

1) When tank-mixing Gramoxone and Reflex, use a non-ionic surfactant (NIS) that contains a minimum of 80% active ingredient.

2) With spray volumes of 10 GPA or more, use NIS at 2 qt/100 gal (0.5% v/v).  Use 1 gal/100 gal (1% v/v) when spraying less than 10 GPA.

3) Mix chemicals in the following order:

a) Add half of the required amount of clean water to the spray tank.

b) Start the sprayer agitation system and continue agitation throughout mixing and spraying.

c) Add the required amount of non-ionic surfactant to the spray tank.

d) Add the required amount of Reflex to the spray tank.

e) Add the required amount of Gramoxone brands to the spray tank.

f) Add the remaining amount of clean water to the spray tank.

Zidua® Herbicide (Prostko)

Just got through looking at some popular press articles and noticed that there were several advertisements for a new herbicide sold under the trade name of Zidua®.  The UGA Weed Science Team has been evaluating this herbicide for several years so we have some good data for sure.  Here are a few things you might need to know about this new product:

Trade Name: Zidua®

Active Ingredient: pyroxasulfone (It was tested under experimental number KIH-485)

Manufacturer: BASF

Mode of Action:  Inhibits the synthesis of very long chain fatty acids.  Same mode of action as Dual and Warrant. (MOA = 15)

Formulation: 85WDG

Typical Use Rate: 1-2 oz/A

Estimated Cost: $6.50/oz

Current Registrations: Field Corn (Zidua® is listed in Field Corn section of the 2013 UGA Pest Control Handbook)

Future Registrations: soybean, sunflower, wheat, cotton (?), peanut (?)

Field Corn Application Methods:  PPI, PRE, or POST but does not have POST activity.  Only provides residual control.

Weeds Controlled:  Small seeded broadleaf weeds and annual grasses.  In UGA tests, it has provided excellent control of Palmer amaranth

General Comments:

Zidua will compete for market share against similar herbicides such as Dual Magnum or Warrant.  The one big advantage that this herbicide has over these is that its use rate in much lower.  I am not expecting Zidua to change the world but it does give growers another residual herbicide option to choose from.  The active ingredient, pyroxasulfone, will also be available in the following herbicide pre-mixes:

Anthem = pyroxasulfone + Cadet (FMC)

Anthem ATZ = pyroxasulfone + Cadet + Atrazine (FMC)

Fierce = pyroxasulfone + Valor (Valent)

Registrations for the above herbicides are pending.  For a copy of the current Zidua label, please refer to the following link:

http://www.cdms.net/LDat/ldAMK000.pdf

Check out the following Zidua® pictures from my 2012 field research:

Managing Weeds in Wheat (A. Stanley Culpepper)

With a warm December, numerous winter weeds are up and growing aggressively.  For wheat that was planted timely, herbicide applications are usually needed around Christmas.

Broadleaf weeds are common in wheat but can be managed effectively if herbicide applications are timely. Numerous herbicide options exist and six of these options are shown below.

Herbicide Option	Wheat Stage of Growth	Weeds
Harmony Extra1 + MCPA2 or Harmony Extra1 + 2,4-D2	Fully tillered	Wild radish, henbit, chickweed, primrose, and most other broadleaf weeds.
Harmony Extra1 followed by MCPA or 2,4-D	After 2 leaf & before flag leaf followed by fully tillered
Harmony Extra1	After 2 leaf & before flag leaf	Henbit, chickweed, most other broadleaf weeds EXCEPT primrose and radish larger than 1”.
2,4-D or MCPA	Fully tillered	Wild radish and primrose.
PowerFlex	Three leaf but before jointing	Wild radish, ryegrass and less than 1.5” henbit or chickweed
Osprey	Emerged but before jointing	Ryegrass, annual bluegrass, and less than 2” henbit or chickweed

¹Harmony Extra, Harmony Extra Total (Sol) and generic products are available, use correct rate.

²MCPA or 2,4-D can be applied at 12-16 oz/A; MCPA is “softer” on wheat.

Annual ryegrass is a serious pest of wheat, especially in middle and North Georgia, primarily due to herbicide resistance.  Growers must rotate herbicide chemistry. Osprey and PowerFlex have the same mode of action thus rotating these herbicides is not an effective approach in rotating herbicide chemistry.  Osprey/PowerFlex should be rotated with Axial; a piece of land should never be treated two years in a row with PowerFlex/Osprey OR Axial.  In addition to rotating herbicides, one must implement cultural practices such as tillage (deep tillage helps considerably) and crop rotation (allowing use of other herbicides such as Roundup) in a ryegrass management program.  There are Georgia growers with ryegrass resistant to Axial, PowerFlex, Osprey, and Hoelon and the production of small grains is no longer economically feasible.  Ryegrass will develop resistance to herbicides more quickly than any other known plant.

All “ryegrass” herbicides should be applied prior to 2 tiller ryegrass!  Mixtures with Harmony will improve broadleaf weed control; however, do not mix these products with 2,4-D or MCPA.

Herbicide Option	Wheat Stage of Growth	Weeds in Addition to Ryegrass
Axial XL	Two leaf up to pre-boot.	None
PowerFlex	Three leaf up to before jointing.	Wild radish < 6”, henbit and chickweed < 1.5”
Osprey	Before jointing.	Annual bluegrass; wild radish < 4”, henbit or chickweed < 2”