Herbicides Used Preemergence to Weeds

acetochlor (Surpass): REI 12h, Group 15.  Not for use in New Hampshire. Works to inhibit weed seed germination, and will not work on emerged weeds.  Labeled for control of annual grasses and broadleaf weeds.  Can be used early preplant, preplant incorporated, preemergence, postplant-preemergence, and early crop postemergence.    Rates based on both soil texture and tillage system used (conventional, reduced, or no-till).  Read label for proper rate selection. Also see label for herbicides approved as tank-mixing partners. 

dimethenamid (Outlook): PHI 50d, REI 12h, Group 15.  May be applied preplant surface, preplant incorporated, preemergence, or postemergence to corn up to12-inches tall. May be applied in a single application or two split applications.  When used as a single application, apply as a single application (12 to 18 oz/A on coarse-textured soil and 14 to 21 oz/A on finer textured soils.  See label for specific maximum application rates of depending on soil type and organic matter content.  A split application may be used (10 to 14 oz/A per application, not to exceed 21 oz/A total).  Allow a minimum of 14 days between applications. Do not exceed a seasonal total of 24 fl ozs/A.  If two applications are made, apply no more than 8 to 16 oz/A during the first application (applied preplant, preemergence, or postemergence), then apply the remainder (8 to 16 oz/A) of the seasonal maximum rate during the second application (postemergence).  Can be tank ,mixed with many other herbicides, see label for details.  Check with seed supplier for potential varietal susceptibility to injury. Outlook is a selective residual herbicide for controlling many annual grasses, annual broadleaf weeds, and sedges as they germinate. Will not control emerged weeds.

pendimethalin (Prowl H2O): REI 24h, Group 3. Apply before weed germination. Emerged weeds will not be controlled.  Work against annual grasses and some broadleaf weeds.  Can be used after planting but before weeds germinate and crop emerges, or after corn emerges until it is 20 to 24-inches tall or at V8.  Rate based on soil texture, see label for details.  When used after planting, there is potential for crop injury if herbicide is moved into the seed zone.  Minimize the potential for crop injury by preparing a firm seedbed and planting corn seed at least 1.5" deep.  If heavy rains follow an application to dry soil, Prowl can move to the seed zone and cause crop injury. Specific weeds for which this herbicide should be considered include triazine-resistant lambsquarters, and velvetleaf. 

pyroxasulfone (Zidua): PHI 37d, REI 12h, Group 15.  A root-and-shoot growth inhibitor that controls susceptible germinating seedlings before or soon after they emerge from the soil. Application rates vary depending on soil texture, see label for details. May be applied preplant surface, pre-plant incorporated, preemergence, or early postemergence to corn for residual preemergence control of weeds. See label for application instructions for each timing.  Plant corn seed at least 1" deep.  Labeled for use against many annual grasses and broadleaf weeds. Controls most annual grasses including crabgrass, panicum, foxtails, and barnyardgrass.  Weak on common lambsquarters but will control redroot pigweed, carpetweed, nightshade, and common purslane.  Has activity on yellow nutsedge. 

s-metolachlor (Dual Magnum)PHI 30d, REI 12h, Group 15.  Can be used either preplant surface, preplant incorporated, preemergence, or lay-by.  See label for application instructions and rates based on timing and soil type. 

simazine (Princep): PHI 45d, REI 12h, Group 5. Apply up to 2 qt/A preplant incorporated or to the soil surface immediately after planting before corn emerges. Use alone only if annual grasses are not a problem.  Do not apply on highly erodible soils unless there is at least 30% plant residue cover.