For no-till 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, still need a non-selective herbicide. These implements are not weed control tools.
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 can be used at 1 to 2 oz with the burndown application, but there must be a 7-day period between application and planting wheat. Valor is not labeled for barley.
Axiom and Zidua can be used at wheat emergence (Axiom at the spike stage and Zidua when sprout is at least 0.5 inches). Both Axiom and Zidua are only labeled for winter wheat, not barley. Neither provides control of emerged weeds but can have utility in situations of needing limited residual control shortly after planting. UD Research Program has over three years of experience with Axiom and it provides broad-spectrum control including annual ryegrass. Zidua has provided annual ryegrass in limited trials. Neither product will provide full-season control.
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 postemergence option.
ALS-resistant common chickweed has been confirmed in Delaware. These biotypes are not controlled with Harmony Extra, Osprey, PowerFlex or Finesse. Currently, UD Research Program has had good control with Glory. There is a 24-c label for Glory in Delaware (in other states, check before applying). Glory is a metribuzin product from MANA. Application needs to be made after wheat or barley are at the 2-leaf stage. 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. Starane Ultra has shown some activity, 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.
Control of cereal rye in wheat or barley is difficult. In fields where the rye cover crop or the wind-breaks produced seeds in the spring, work the soil at least 14 days prior to seeding. The tillage will stimulate the rye seeds to germinate and then kill the rye plants with additional tillage or with glyphosate at planting. While we have not tried vertical tillage, I suspect it would not cause enough rye seeds to germinate. There are no herbicides to control cereal rye in a winter wheat or barley crop.
