By Scout Nelson
Soybean plants across South Dakota are beginning the reproductive growth stage known as R1, which marks the start of flowering. The first sign of this stage is the appearance of flowers on the first growth node of the plant. While early planted soybeans may appear larger than later planted fields, the change from vegetative growth to reproductive growth is mainly controlled by day length rather than plant size.
Eric Jones, Assistant Professor and SDSU Extension Weed Management Specialist, along with Philip Rozeboom and Stephen Robertson, reminds producers that soybean growth stages are important when making weed management decisions. Their guidance highlighted that many herbicides have strict application limits once soybean plants begin flowering.
The R1 stage is an important time for farmers because some herbicide products can still be used, while others are no longer allowed. Glufosinate products, including Liberty Ultra, Interline, and Cheetah, can be applied during the R1 stage. Enlist One, which contains 2,4-D choline, can be applied through the R2 stage when soybeans reach full bloom.
Although the most important weed control period in soybeans is usually between the V1 and V4 growth stages, some fields may still need weed management due to cool and dry growing conditions. Smaller soybean plants may require additional weed control to help maintain yield potential. Producers should always review product labels and current pest management guidelines before applying herbicides.
If soybean plants are too mature for herbicide applications, farmers should avoid spraying. Late applications may not damage the crop directly, but herbicide residues can move into soybean grain and cause problems during sale or delivery.
Manual weed removal, often called “walking beans,” remains an option for managing weeds before flowering. Removing weeds by hand can help reduce competition and support soybean production.
Photo Credit: istock-oticki
Categories: South Dakota, Crops, Soybeans