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  4. »eUpdate 803 June 5th, 2020»Federal court vacates registration of some dicamba herbicide labels

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Department of Agronomy

Kansas State University

1712 Claflin Rd.

2004 Throckmorton PSC

Manhatan, KS 66506

785-532-6101

agronomy@ksu.edu

Extension Agronomy

Federal court vacates registration of some dicamba herbicide labels


On Wednesday, June 3, the Ninth Circuit Court of Appeals in San Francisco issued a decision that nullifies the current labels for Engenia, FeXapan, and XtendiMax herbicides. The decision was in response to a 2017 lawsuit stating that the EPA understated the risks of using the products. There are a lot of questions about the consequences of this decision and few answers at the moment. We are in a position where we must wait for the legal process to play out and for the EPA to issue clear guidance. What we do know at the present time is that the court order makes applications of Engenia, FeXapan, and XtendiMax illegal. However, the current statement from the Kansas Department of Agriculture is that these products are still available for use in Kansas.

This is a season where weed management activities are essential and decisions must be made quickly. Some of the best alternatives to dicamba will be products containing Group 14 herbicides such as fomesafen (Reflex, FlexStar). A list of these products is presented in Table 1. Weed size and spray coverage will be important factors affecting control by these products. Also, consider that dicamba does have some residual activity that you may want to replace and is important for control of difficult weeds like Palmer amaranth. Group 15 herbicides containing active ingredients such as metolachlor or acetochlor will be the likely candidates for this purpose. These products are also listed in Table 1.

 

Table 1. Herbicide alternatives to dicamba for post-emergence control of broadleaf weeds in dicamba-tolerant soybean.

Herbicide

Group

Active ingredient (s)

Comments

Classic

2

chlorimuron

Many pigweed populations are resistant

Cobra, others

14

lactofen

Expect crop injury

Dual II Magnum, others

15

S-metolachlor, metolachlor

Apply through V3

FirstRate

2

cloransulam

Many pigweed populations are resistant

Flexstar GT

14 + 9

fomesafen + glyphosate

Expect crop injury

10-month rotation to corn

Regional application restrictions

Flexstar, Reflex, others

14

fomesafen

Expect crop injury

10-month rotation to corn

Regional application restrictions

Marvel

14 + 14

fluthiacet + fomesafen

Apply before full flower soybean

Expect crop injury

Outlook

15

dimethenamid-P

Apply before V5

Prefix

14 + 15

fomesafen + S-metolachlor

Expect crop injury

10-month rotation to corn

Regional application restrictions

Pursuit

2

imazethapyr

Many pigweed populations are resistant

Raptor

2

imazamox

Many pigweed populations are resistant

Storm

14 + 6

acifluorifen + bentazon

Expect crop injury

Synchrony

2 + 2

thifensulfuron + chlorimuron

Many pigweed populations are resistant

Tavium

4 + 15

dicamba + S-metolachlor

Apply through V4 or 45 days after planting

Ultra Blazer, others

14

acifluorifen

Expect crop injury

Warrant

15

acetochlor

Apply before R2 soybean

Warrant Ultra

14 + 15

fomesafen + acetochlor

Apply before R2 soybean

10-month rotation to corn

Regional application restrictions

Zidua

15

pyroxasulfone

Apply through V6

 

We will share any updates to this decision as more information and guidance becomes available in the coming days.

 

 

Sarah Lancaster, Extension Weed Science Specialist
slancaster@ksu.edu