Taking an environmentally sensitive approach to pest management
With the wet conditions throughout most of the state, I have already received a few calls about producers sacrificing their preemergence corn herbicide applications in order to try to get as much corn planted as possible. It seems likely that this situation will only get worse and that many growers will not be able to get back on these fields until well after the corn has emerged. Luckily, many of our preemergence corn herbicides have labels that allow them to be applied to emerged corn fields. One notable exception to this is Balance Pro, which cannot be applied to emerged corn or injury will occur. Table 1 provides a list of the preemergence herbicides that can be applied to emerged corn, as well as information about the maximum corn height and/or stage in which these applications should be made.
| Table 1: Preemergence herbicides that can be applied to emerged corn | |||
| Herbicide Trade Name |
Active Ingredient(s) | Maximum Corn Height/Stage for Broadcast Applications | Maximum Weed Height/Stage for Broadcast Applications |
| Aatrex/Others | atrazine | 12 inches | Apply before weeds exceed 1.5 inches in height. When applied with crop oil, apply before weeds reach 4 inches in height. |
| Bicep II Magnum/Cinch ATZ | atrazine + metolachlor | 5 inch | Apply until weeds reach the 2-leaf stage. Applications made beyond the 2-leaf stage will not provide satisfactory weed control. |
| Bullet | atrazine + alachlor | 5 inch | Apply until weeds reach the 2-leaf stage. Applications made beyond the 2-leaf stage will not provide satisfactory weed control. |
| Callisto | mesotrione | 30 inches or 8-leaf stage | Apply to weeds that are less than 5 inches in height. |
| Camix | metolachlor + mesotrione | 5 inches | Apply before grass emergence but will control some broadleaf weeds less than 3 inches in height. |
| Degree, Harness, Surpass, TopNotch | acetochlor | 11 inches | Apply before weed emergence. Will not provide postemergence weed control and requires a tank-mix partner. |
| Cinch, Dual II Magnum | metolachlor | 40 inches | Prior to emergence. Will not provide postemergence weed control and requires a tank-mix partner. |
| Frontier, Outlook | dimethenamid | 12 inches | Apply before weed emergence. Will not provide postemergence weed control and requires a tank--mix partner. |
| Degree Xtra, FulTime, Keystone | atrazine + acetochlor | 11 inches | Apply prior to weed seedling emergence or in a tank mixture that controls emerged weeds. |
| G-Max Lite | atrazine + dimethenamid | 12 inches | Apply before broadleaf weeds are greater than 1.5 inches tall and before grass weeds emerge. |
| Guardsman | dimethenamid | 12 inches | Apply before weeds are greater than 1.5 inches tall or in a tank mix with products that control emerged weeds. |
| Guardsman Max | atrazine + dimethenamid | 12 inches | Apply before weeds are greater than 1.5 inches tall or in a tank mix with products that control emerged weeds. |
| Harness Xtra | atrazine + acetochlor | 11 inches | Apply before grass weeds reach the 2-leaf stage or in a tank mixture with a herbicide that controls emerged weeds. |
| Hornet | flumetsulam + clopyralid | 20 inches or V6 stage | Apply to specified weeds up to 8 inches in height. |
| Lasso | alachlor | before emergence | Apply before weed emergence. Will not provide postemergence weed control and requires a tank-mix partner. |
| Lexar | atrazine + metolachlor + mesotrione | 12 inches | Apply to broadleaf weeds less than 5 inches in height. Will not provide adequate control of most grasses that are emerged at the time of application. |
| Lumax | atrazine + metolachlor + mesotrione | 12 inches | Apply to broadleaf weeds less than 5 inches in height. Will not provide adequate control of most grasses that are emerged at the time of application. |
| MicroTech | alachlor | 5 inches | Apply before weed emergence. Will not provide postemergence weed control and requires a tank-mix partner. |
| Prowl H20 | pendimethalin | 30 inches or 8-leaf stage | Apply before weed emergence. Will not provide postemergence weed control and requires a tank-mix partner. |
| Python | flumetsulam | 2 inches or before first leaf is unfurled (spike stage) | Apply before weed emergence. Will not provide postemergence weed control and requires a tank-mix partner. |
| Resolve | rimsulfuron | 12 inches or exhibiting 6 leaf collars, whichever is more restrictive | Apply to grasses 1 to 2 inches in height and broadleaf weeds 1 to 3 inches in height. Will provide postemergence weed control of labeled weeds and some residual control of later-emerging weeds. |
| SureStart | acetochlor + flumetsulam + clopyralid | 11 inches | Apply before weed emergence up to 1 to 2 inch weeds. If weeds are emerged, apply in combination with another herbicide with contact activity. |
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REVISED: April 5, 2012