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Weed Seed Production in Small Grains Stubble (08/31/17)

Fields with beautiful golden brown small grain stubble are turning green from late emerging weeds like waterhemp or from regrowth of grass and broadleaf weeds following harvest.

What are various ideas to manage seed production in stubble? There are several to consider:

Tillage is a time-proven method to manage seed escapes in stubble. Tillage is best when weeds are small and before weeds make seed. Tillage may also be beneficial to incorporate volunteer cereals into soil for cover crop to protect soil from blowing or eroding. In an experiment conducted at Prosper, ND in 2016, volunteer wheat provided 40% visual ground cover compared to seeded species, including 60% from winter wheat, 70% from oat and tillage radish, and 85% from cereal ryegrass.

Herbicide options are available to control weeds in stubble fields. Glyphosate (at 0.75 to 1.5 lb AE) plus 2, 4-D amine (at 0.75 to 2 lb.) controls broadleaf and grass weeds in stubble. Gramoxone (Paraquat) (at 0.38 to 1 lb.) with 15-20 gallons of water per acre is another option when weeds are small. Gramoxone will not provide as strong control on volunteer cereals as glyphosate. There are other options but you need to check the herbicide label to be aware of any rotational restrictions for next year’s crop.

For some, mowing may provide effective control of broadleaf weeds that are tall enough, or with seed inflorescences above the height of cut. Keep in mind that fields may need to be mowed multiple times to eliminate weeds that grow back from axillary buds.

Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

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