2,4-D Herbicide Injury to Wheat

Wheat fields that received an application of 2,4-D herbicide last fall are showing injury sympoms. The damage found ranges from 10% up to 90%+. The injury appears as distorted stems, crinkled leaves and stunted plants. Difference have been noted by variety, planting date and stage of tillering last fall. Observations and labels information have been summarized by Dr Mark Loux, OSU Extension Agronomist in the May 19th CORN Newsletter from OSU Extension. "Many of the fields that were most severely affected were treated with a combination of Peak and 2,4-D last fall, and the use of 2,4-D in these treatments may be a primary cause of the injury. Peak is labeled for postemergence application to wheat in fall or spring, from emergence until the second node is detectable in stem elongation (Feeke’s Growth Stage 7). Labels for 2,4-D products vary in their wording on the use of 2,4-D in wheat. The more conservative labels state that 2,4-D should be applied in the spring after wheat has fully tillered, while others (including some products used in the affected fields) state that application can be made after tiller initiation with no mention of fall versus spring application."

Options maybe limited for the most severely affected fields. 1) The Peak label has a 10 month recrop restriction for soybeans. pH above 7.8 also play into decisions about replanting. Refer to product label for details. A bioassay maybe used and is outlined in the previously mentioned CORN Newsletter article. 2) Field could possibly be harvested as wheatlage then replanted to corn. Restrictions on forage use should be checked. 3) Field could be sprayed with roundup and planted to corn. These fields would then need to be scouted for armyworm development.

For more details see the Crop Observation and Recommendation Newsletter-CORN.