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
Collection of susceptible and resistant kochia plants in sample pots demonstrating herbicide effectiveness.

Mixing it Up: Fall Herbicide Mixtures for Kochia Management

Fall-applied residual herbicides can help manage early emerging weeds, such as kochia, by using snowmelt and early spring rainfall as activating precipitation to move the herbicide into the soil layer of emerging weed seedlings.

Absinth wormwood, biennial thistle rosette, and leafy spurge.

Recent Rainfall Likely to Improve Fall Herbicide Applications for Noxious Weed Management

Under hot and dry conditions, weeds are stressed and herbicide activity decreases, leading to poor management. While recent rain events have impeded row crop harvest, the moisture is welcomed to improve the activity of fall herbicide performance for noxious weeds in pastures and rangelands.

SD Sundog growing within a series of crop performance testing plots.

Utilizing Cool-Season Crops for Weed Management

For producers facing increasing challenges from herbicide-resistant Palmer amaranth or waterhemp, incorporating a cool-season crop can provide another tool for diversifying weed management.

aerial view of South Dakota farm and surrounding land

Crops

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

Velvet leaf foliage and seed pods.

What is Velvetleaf?

Velvetleaf is a large weed with soft leaves that’s normally associated with corn and soybean fields. However, we’re hearing more gardeners and specialty crop growers reporting its presence.

soybean pods

Soybean

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

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.