Herbicide Cut-Offs By Wheat Maturity
DR. LARRY STECKEL
JACKSON, TENN.
The wheat has really progressed well over the past two weeks. Some stands that one might think were borderline on keeping have made good progress during that time.
The wheat maturity stage across Tennessee varies quite a bit. Much of the variance is due to the wide range of planting dates last fall coupled with the cold winter which has really checked up growth. This is especially true for later planted fields. The later planted fields particularly those that were seeded with a spreader are behind on maturity relatively speaking.
The more timely planted wheat fields look really good. The wheat in these fields are well on the way to getting to first node. This maturity stage of wheat is a major cut-off point for many herbicides used in wheat. Herbicides like metribuzin, dicamba, Powerflex and Osprey should not be applied to wheat past the first node stage. Dicamba is a good example of this as applications after the first wheat node can later cause poor wheat head formation.
Harmony, 2,4-D, MCPA, Finesse and Axial can be applied later than the first wheat node. Axial, 2,4-D, MCPA and Finesse can be applied to wheat up to the pre-boot stage and Harmony can be applied to wheat up to the flag leaf stage. ∆
DR. LARRY STECKEL: Extension Weed Specialist, University of Tennessee