Small Grain Weed Control

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Be sure to read the herbicide label carefully because some products can be tankmixed with nitrogen but only if the nitrogen is no more than 50% of the spray solution (nitrogen is mixed 1:1 with water). A few specifics:

● Osprey cannot be applied within 14 days of nitrogen application

● Harmony Extra can be applied with nitrogen, but use of surfactant differs depending on concentration of nitrogen and targeted weed species

● Axial XL and PowerFlex can only be applied with nitrogen if it is mixed 1:1 with water; also PowerFlex cannot be applied with nitrogen if the amount is more than 30 lbs of N/A

Axial XL and PowerFlex are two herbicides that are effective on annual ryegrass. Both of these can be double-cropped with soybeans. However, PowerFlex will injure vegetables planted after harvest.

There are reports of fields with poor chickweed control due to resistance to Harmony, Harmony Extra, or Finesse. If you are in that situation, your alternatives are quite limited. Most other small grain herbicides do not provide acceptable chickweed control. One product to suggest is Starane Ultra (from Dow AgroSciences). This product is labeled for wheat and barley and has good crop safety and fair to good chickweed control. However, it will not control other key species such as wild garlic. Starane Ultra can be tankmixed with Harmony Extra to broaden the spectrum of control. Starane Utra by itself does not need an adjuvant and can be applied in nitrogen. Be sure to read and follow label directions.

Finally, a reminder on timing restrictions for small grain herbicides. The timing restrictions are based on crop safety.

2,4-D – up to jointing stage (pre-jointing)

Banvel/Clarity – up to jointing stage (pre-jointing)

Osprey – up to jointing stage

Buctril – up to boot stage

Harmony Extra or Harmony GT – up to flag stage (pre-flag leaf)

Starane Ultra – up to flag leaf emergence

PowerFlex – jointing

Axial XL – prior to boot

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