Soybean growth stage cutoffs for postemergence herbicide application

Sachin Dhanda, Weed science postdoctoral researcher, Sithin Mathew, Weed science graduate student, and Debalin Sarangi, Extension weed scientist

Soybean field treated with postemergence Cobra
 herbicide (within the label cutoff) showing
 temporary leaf injury. Photo: Sithin Mathew)

The erratic rainfall pattern this cropping season has led to disjointed soybean planting across Minnesota, with some farmers needing to replant their crops. As a result, soybean fields are currently at varying growth stages. Many acres are either receiving postemergence herbicides this week or have not yet been treated. It is essential to adhere to the growth stage cutoffs specified on herbicide labels for postemergence applications and to comply with the preharvest interval (PHI) which is legally required. The PHI represents the minimum time between the last herbicide application and the crop harvest. The restrictions are in place to prevent potential crop injury, herbicide carryover, environmental or food safety issues, and other concerns. If tank mixing two or more herbicides, the cutoff is determined by the most restrictive labels. Always consult herbicide labels prior to application to ensure compliance. Below is an updated table (as of July 3, 2024) summarizing soybean growth stage cutoffs and PHI for commonly used postemergence herbicides.

Table 1. Commonly used postemergence herbicides in soybean with their application restrictions.

Herbicide	Active ingredient	Soybean growth  stage cutoff	Preharvest  interval (PHI)
Anthem Maxx	fluthiacet-methyl +  pyroxasulfone	Through the V6 stage	60 days
Arrow 2EC	clethodim	-	60 days
Assure II, Targa	quizalofop-P-ethyl	-	80 days
Basagran	bentazon	-	30 days for forage or hay
Cadet	fluthiacet-methyl	through full flowering	60 days
Classic	clorimuron ethyl	-	60 days
Cobra	lactofen	R6 (full seed)	45 days
Dual II Magnum	S-metolachlor	-	75 days
Enlist Duo/ Enlist One (for  Enlist soybean	2,4-D + glyphosate / 2,4-D	Through R1	50 days
FirstRate	cloransulam-methyl	Prior to R2 (full flower)	25 days for forage or hay 70 days for grain
FlexStar	fomesafen	-	45 days
Fusilade DX	fluazifol-P-butyl	V5 (not more than 24 fl oz/A; from R1 onwards,  not more than 6 fl oz/A	60 days
Harmony SG	thifensulfuron methyl	Bloom stage	60 days
Liberty 280 SL (only for LibertyLink soybean)	glufosinate	R1	70 days
Outlook	dimethenamid-P	V5	-
Perpetuo/Resource	flumiclorac pentyl + pyroxasulfone / flumiclorac pentyl	V6	60 days
Poast	sethoxydim	-	75 days
Pursuit	imazethapyr	Prior to bloom stage	85 days
Raptor	imazamox	Prior to bloom stage	-
Resource	flumiclorac pentyl	-	60 days
Roundup PowerMax3 (for Roundup Ready soybean)	glyphosate	Through R2	14 days
Scepter 70DG	imazaquin	-	90 days
Select MAX	clethodim	-	60 days
Ultra Blazer	acifluorfen	-	50 days
Varisto	imazamox + bentazon	Prior to bloom stage	30 days for forage or hay
Warrant	acetochlor	Prior to R2	-
Warrant Ultra	acetochlor + fomesafen	Prior to R2	45 days
XtendiMax (for XtendFlex soybean)	dicamba	R1; state and national restrictions applied regarding cutoff dates and temperature	7 days
Zidua SC	pyroxasulfone	V6	-