Sachin Dhanda, Weed science postdoctoral researcher, Sithin Mathew, Weed science graduate student, and Debalin Sarangi, Extension weed scientist
This season’s erratic weather has resulted in very few good spray days in Minnesota, leaving some corn acres without a postemergence herbicide application. Many fields received postemergence treatments very early in the season, prompting farmers to consider a second application to control problem weeds like waterhemp. Herbicide labels typically specify growth stage or crop height cutoffs (whichever comes first) for herbicide application, and the preharvest intervals (PHI) indicate the minimum time required between the last herbicide application and crop harvest. The restrictions are crucial to prevent potential crop injury, herbicide carryover, environmental or food safety issues, and other potential concerns. When tank mixing herbicides, the most restrictive label determines the cutoff. Always consult herbicide labels before application to ensure compliance. Below is an updated table (as of July 3, 2024) summarizing corn growth stage or height cutoffs and PHI for commonly used postemergence herbicides.
 |
| Figure 1. Corn field planted in mid-May requires postemergence herbicides for weed control. Photo: Debalin Sarangi |
Table 1. Commonly used postemergence herbicides in corn with their application restrictions.
| Herbicide | Active ingredient | Corn height/ growth stage cutoff |
Preharvest interval (PHI) |
|---|---|---|---|
| 2,4-D | 2,4-D | Less than 8"; direct spray to 8" to tasseling |
7 days |
| AAtrex 4L | atrazine | 12" | 60 days for forage |
| Accent Q | nicosulfuron | 20"/V6; use drop nozzle for corn up to 36" tall or V10 stage |
70 days for grain and 45 days for forage |
| Acuron | atrazine +S-metolachlor + mesotrione +bicyclopyrone |
12" | 60 days for forage |
| Acuron Flexi | S-metolachlor + mesotrione + bicyclopyrone |
30"/V8 | 60 days |
| Acuron GT (only Roundup Ready corn |
S-metolachlor + glyphosate + mesotrione + bicyclopyrone |
30"/V8 | 45 days |
| Aim EC | carfentrazone-ethyl | V8; use drop nozzle up to V14 | - |
| Anthem Maxx | fluthiacet methyl + pyroxasulfone |
V4 | 70 days for grain and 30 days for forage |
| Armezon PRO | topramezone + dimethanamid-P |
30"/V8 | 45 days |
| Basis Blend | rimsulfuron + thifensulfuron-methyl |
6"/V2 | 30 days |
| Bicep II Magnum | atrazine + S-metolachlor | 12" | 60 days for forage |
| Cadet | fluthiacet-methyl | Up to 48" but before tasseling | - |
| Callisto | mesotrione | 30"/V8 | 45 days |
| Callisto Xtra | atrazine + mesotrione | 12" | 60 days |
| Capreno | thiencarbazone-methyl + tembotrione |
20"/V7; V5 stage for seed corn | 45 days for forage |
| Clarity, Banvel | dicamba | 8"/V5 stage (1 pt/A rate); 36" or 15 days before tassel emergence (0.5 pt/A rate) |
- |
| DiFlexx | dicamba | 36"/V10 | 45 days for forage and grain harvest can be done when crop reaches milk stage |
| DiFlexx Duo | dicamba + tembotrione | 36" or up to (but not including) V7; directed spray V7 to V10 or up to 36" tall or up to 15 days prior to tassel |
45 days for forage and grain harvest can be done when crop reaches milk stage |
| Dual II Magnum | S-metolachlor | 40" | 30 days for forage |
| Enlist Duo (for Enlist corn) |
2,4-D + glyphosate | 30"/V8; use drop nozzles from 30 to 48" |
50 days for forage |
| Enlist One (for Enlist corn) |
2,4-D | 30"/V8; use drop nozzles from 30 to 48" |
30 days for forage |
| Halex GT (for Roundup Ready corn |
S-metolachlor + glyphosate + mesotrione |
30"/V8 | 45 days |
| Harness Max | acetochlor + mesotrione | 11" | 60 days |
| Hornet | flumetsulam + clorpyralid | 20"/V6; use drop nozzles from 20 to 36" |
85 days for grain and 45 days for forage |
| Impact | topramezone | - | 45 days |
| Impact Z | atrazine + topramezone | 12" | 45 days |
| Katagon | tolpyralate + nicosulfuron | 20"/V5 | 70 days |
| Kyro | acetochlor + clopyralid + topramezone |
24" | 45 days for forage |
| Laudis | tembotrione | V8 | 45 days for forage |
| Liberty 280 SL (for LibertyLink corn) |
glufosinate | V6; Use drop nozzles up to 36" height |
70 days for grain and 60 days for forage |
| Maverick | pyroxasulfone + mesotrione + clopyralid |
18"/V6 | 30 days |
| Outlook | dimethanamid-P | 12"; direct application should be made from 12 to 36" |
40 days for forage |
| Perpetuo | flumiclorac + pyroxasulfone | V6 | 28 days for forage |
| Realm Q | rimsulfuron + mesotrione | 20"/V6 | 70 days for grain and 45 days for forage |
| Resicore XL | acetochlor + mesotrione +clopyralid |
24" | 45 days |
| Resolve Q | rimsulfuron + thifensulfuron | 20"/V7 | 30 days for forage |
| Resource | flumiclorac pentyl | V10 | 28 days for forage |
| Revulin Q | nicosulfuron + mesotrione | 20"/V6; Use drop nozzles from 20 to 30" |
70 days for grain and 45 days for forage |
| Roundup PowerMax3 (for Roundup Ready corn) |
glyphosate | 30"/V8; Use drop nozzles from 30 to 48" tall |
50 days |
| Shieldex 400SC | tolpyralate | 20"/V6 | 45 days for grain and 21 days for forage harvest |
| Sinate (for LibertyLink corn) |
topramezone + glufosinate | 24"/V7; Use drop nozzles from 24 to 36" corn |
70 days for grain and 60 days for forage |
| Status | dicamba + diflufenzopyr | 36"/V8 | 72 days for grain and 32 days for forage |
| Stinger | clopryalid | 24" | 40 days for forage |
| Storen | bicyclopyrone + mesotrione +S-metolachlor + pyroxasulfone |
V8 | 45 days |
| Surestart II | acetochlor + flumetsulam + clopyralid |
11" | 85 days |
| Tough 5EC | pyridate | V8 | 68 days |
| Warrant | acetochlor | 30"; Use drop nozzles for 24 to 30" |
40 days for forage |
| WideMatch | clopyralid + fluroxypyr | V5 | 90 days |
| Yukon | halosulfuron-methyl + dicamba |
20"; Use drop nozzles for 20 to 36" |
30 days for forage |
| Zidua SC | pyroxasulfone | V8 | - |
Comments
Post a Comment