Soybean Weeds

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Best Management Practices for Soybean Production

This is your unbiased, research-based guide to soybean production to help increase yield, reduce input costs and protect your investment.

All Soybean Weeds Content

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Soybean

SDSU Extension is your partner to increase yields and improve efficiency.

aerial view of South Dakota farm and surrounding land

Crops

During the growing season, SDSU Extension provides weekly production recommendations.

Green soybeans plants with a light grey background. All soybean plants have purple flowers which indicates the plants have reached reproductive stage 1.

Soybean Plants Are Entering the Reproductive Stage (R1): Last chance to spray select herbicides

The summer solstice roughly marks the date when soybean plants switch from vegetative growth to reproductive growth. An important aspect of the reproductive growth stage is that many herbicides can no longer be applied after plants reach any bloom stage.

: Two photos with various plants that are brown, yellow, and/or green. A blue pen is in the foreground of each photo for size reference.

Clock tells the time of the day, not when the job is done. Is that true for weed management?

Common banter at the farm gate implies farmers work long days to get the job finished. However, weed management may improve if spraying stops at a particular time of day.

A red, weed hoe next to a freshly cut, green weed surrounded by brown soil.

Reminder: Cutoff for over-the-top dicamba products labeled for soybean is June 30 or R1 growth stage in South Dakota

Over-the-top dicamba products for application in soybean have been relabeled for the 2026 growing season. A stipulation for applying these herbicides is a cutoff date of June 30 or R1 soybean.

Wind carrying a cloud of topsoil over a dry, bare field.

2026 Growing Season: Forecasted dry weather and the implications on postemergence herbicide activity

Weather cannot be controlled, but there are variables we can control to help increase the effectiveness of postemergence herbicides during drought conditions.

Picture of mostly brown soil with two, small, faintly green plants near the center.

Waterhemp Has Emerged in South Dakota

Waterhemp seedlings were observed in Volga, South Dakota and other observations of emerging seedlings have been and reported elsewhere in the state. While the seedlings are still small, forecasted rain and increased temperatures will cause these plants to grow rapidly.

Herbicide sprayer on the edge of an emerging soybean field.

Syngenta to Stop Production of Gramoxone®

Global pesticide developer Syngenta announced on March 3, 2026 that they will cease global production of the herbicide product Gramoxone® (paraquat), a pivotal source of weed control in corn and soybean production, by June 30, 2026.

Mesonet camera overlooking spring pasture and cropland in Avon, South Dakota.

Great Temperature Shifts This Spring: Implications for burndown herbicide applications

The 2026 growing season is beginning as temperatures begin to increase. The increased temperatures are favorable for growing conditions, however, great temperature shifts throughout the day may adversely affect the activity of herbicide applied for preplant burndown.

Field of green soybean plants with green corn and blue sky in the background.

Performance of Enlist One (2,4-D) and Liberty (Glufosinate) Applied in Mixture or Sequentially for Weed Control in Soybean

Trial results for Enlist One (2,4-D) and Liberty (Glufosinate) on weed control in soybean.