Soybeans are at full maturity (R8) when the crop is tan-brown, 95% of the pods are brown, seeds rattle in the pod and all leaves are dropped. The crop is ready to harvest in 5-10 days when seed moisture is <14%.
Pre-harvest Weed Control and Desiccation Timing
When selecting pre-harvest products for soybean crops, it is important to choose the right product for the intended outcome and apply it at the right time. For example, desiccants are used for crop dry down, while pre-harvest weed control products are used to control perennial weeds prior to harvest. They do not speed up maturity or dry down crop seeds faster.
Apply desiccants when 80 to 90% leaf loss has occurred and 80% of pods are yellow. Use high water volumes when applying desiccants for proper crop coverage and dry down. Diquat (Reglone®, Reglone® Ion, Desica, Diquash), carfentrazone (Aim®), and saflufenacil (Heat®) are registered products for soybean desiccation.
Apply pre-harvest weed control products when seed moisture is less than 30%, stems are green or brown, 80 to 90% leaf loss has occurred and pods are brown. Various glyphosate products are registered for pre-harvest weed control in soybeans. Heat® (saflufenacil) and Aim® (carfentrazone) may be tank mixed with glyphosate for combined contact and systemic activity pre-harvest. Do not apply glyphosate to soybean crops grown for seed due to the risk of irregular germination and seedling development.
Maximum Residue Limits (MRLs)
Always consult your buyer or exporter before selecting a pre-harvest or desiccation product to avoid market risks. Take appropriate steps to apply these products properly to prevent residues from exceeding maximum residue limits (MRLs) set by regulatory agencies in Canada and importing countries.
Always read and follow pesticide label directions for the correct rates, surfactants, water volumes, application timing and pre-harvest intervals.
Soybeans can be direct combined (straight cut) or swathed, though direct combining is the preferred harvest method. If swathed, soybeans should be combined shortly after swathing to avoid the risk of reduced quality. Soybeans are easily damaged by precipitation if left in the swath long.
Direct combine soybeans with a flex header when pods are dry, seeds are hard and seed moisture is <14%. Combining can take place when seed moisture is below 20%, but soybean must be stored <14%. Seeds are prone to damage at <12% moisture. Carefully adjust cylinder speed and concave clearance to minimize cracking and splitting of seed.
Measure harvest yield loss regularly using the Bean App soybean Harvest Loss Assessor. Over 80% of harvest losses occur at the header. Reduced harvest speed at <5 mph will greatly diminish losses (4 beans/ ft2 = 1 bu/ac). Also consider using a floating cutterbar to minimize harvest losses. Read more about preventing soybean harvest loss.
- Monitor soybeans every other day once they begin to mature. Consult the MPSG Soybean Maturity Guide to help time your harvest.
- Apply desiccants when 80 to 90% leaf loss has occurred and 80% of pods are yellow.
- Apply pre-harvest weed control products when seed moisture is <30%, stems are green or brown, 80 to 90% leaf loss has occurred and pods are brown.
- Direct harvest soybeans when seed moisture is 13-14%. Avoid harvesting soybeans at less than 13% moisture to avoid seed damage.
- Direct combine soybeans with a flex header at <5 mph.
- Adjust the cylinder speed and concave clearance carefully to prevent seed cracking and splitting.
- Aim to lower the cutter bar within two inches of the ground to capture the lowest pods, preventing stubble losses.
- Measure losses regularly during harvest to optimize your combine settings. Use our Bean App tool – the Harvest Loss Assessor for soybeans.