Herbicide carryover considerations when recropping wheat
Another consideration is how to kill the wheat crop if producers plan to recrop. For glyphosate to be effective, it has to be absorbed by healthy, growing plant parts. Wheat that has been injured and is not dead yet, but not growing well, may be hard to kill with glyphosate.
The best approach is to wait until the wheat is actively regrowing before applying glyphosate. Paraquat is not a good alternative as it burns back the treated leaves, and is not translocated to the crowns and lower buds, thus the wheat plant often can regrow from these structures.
Always refer to the specific herbicide label regarding crop rotation guidelines and restrictions. Label guidelines for crop rotation are often complicated by soil pH and geography. Some product labels have very rigid crop rotation restrictions, while other labels allow shorter intervals in the case of catastrophic crop failure, as long as the producer is willing to accept the risk of crop injury. Another confusing issue may be the existence of supplemental herbicide labels with shorter crop rotation guidelines than the regular label. Herbicides with supplemental crop rotation labels include Finesse, Ally, and Ally Extra.