Considerations for Small Grain Weed Control

Mark VanGessel, Extension Weed Specialist;

For no-till small grain fields, a non-selective herbicide needs to be used prior to planting. If grasses or perennial weeds are present, glyphosate is a better choice than paraquat. Fields worked with a vertical tillage implement for residue management often need a non-selective herbicide since these implements are not very effective tools for weed control.

There are few effective herbicides labeled for preemergence applications. Sharpen is labeled for wheat and barley but we have limited data in the region. Valor or Afforia can be used with the burndown application, but there must be a 7-day period between application and planting wheat. We have seen some wheat stunting and injury on coarse-textured soils, particularly if there is rainfall shortly after planting. Plant wheat at least 1-inch deep, otherwise risk of injury is increased. Neither product is appropriate for fields planted by “spinning the seeds” on the soil surface and shallow incorporation with a disk or turbo-till. Valor and Afforia are not labeled for barley.

Axiom, Anthem Flex and Zidua can be used after wheat emergence, typically spike stage. These products are only labeled for winter wheat, not barley. They do not provide control of emerged weeds but can have utility in situations requiring residual control shortly after planting. They all have good activity on annual ryegrass, but they may not provide full-season control. In limited trials, Anthem Flex and Zidua have provided good control of annual bluegrass. The labels of all three products do not allow spinning the seeds onto the soil surface and shallow incorporation. Seeds need to be planted with a drill and refer to the labels for precautions on seeding depth.

Products that provide postemergence control include: Glory, Harmony, Harmony Extra, Huskie, Starane Ultra, Osprey, PowerFlex, Axial XL, or 2,4-D. Other labeled herbicides with a limited fit include Finesse, Maverick and Prowl H2O.

Control of annual ryegrass has been good with Osprey, PowerFlex, or Axial XL. However, ALS-resistant ryegrass has been identified in Delaware and these populations will not be controlled by Osprey or PowerFlex. Furthermore, Finesse will not control these populations. In situations where ALS resistance is suspected, use of Axiom or Zidua shortly after planting, followed Axial XL is the best program.

ALS-resistant common chickweed has been confirmed in Delaware. These biotypes are not controlled with Harmony Extra, Osprey, PowerFlex or Finesse. UD Weed Research Program has had good control with Glory. There is a 24-c label for Glory in Delaware (in other states, check before applying). Applications in the early spring have provided better crop safety than fall application. Be sure to read the label for application rates (which change with application timing). Some wheat and barley varieties are sensitive to Glory, so be careful to use on varieties with known crop safety. The other option for common chickweed control is Starane Ultra which has shown fair to good control, but often not killing common chickweed, but providing good suppression. Starane Ultra can be used either in the fall or spring.

Jagged chickweed control was evaluated last year in UD trials, and Glory and Huskie provided good postemergence control.

Henbit control with Harmony Extra has been inconsistent in our trials and many reports from the industry have confirmed our observations. Starane Ultra, Glory or Huskie have all provided good to excellent henbit control.