Sunshine and warmer weather are accelerating crop and weed growth. Because of varied planting and replanting dates, both corn and soy post herbicide applications are underway. Largest corn is V9 – V10 stage, soy is V4 to V5 and nearly R1 (beginning bloom, one open flower at any node on the main stem). We are getting flowers on soy over a week before summer solstice! Despite what some of us learned about the connection between the longest day of the year and flowering, this phenomenon is becoming more frequent with earlier plantings. Photoperiod sensitive soybeans are considered a short-day plant. Despite the inference, flower induction is triggered with a longer night length. The soy plant’s ability to measure night length starts early, when the unifoliate leaflets are present and a young trifoliate can be detected at the second node. Dependent upon the soybean variety and maturity, once that plants critical night length is reached, flowering is initiated, before or after June 21st.
With our Dicamba products for Xtend technology soy reaching their June 12th application cutoff in Illinois, we should also look at label recommendations for Enlist products. The Enlist One label specifies for post applications applied to Enlist traited soy, ” Apply when weeds are no larger than 6 inches and any time after soybean emergence through the R1 growth stage.” As always, take the time to read and follow label directions before mixing and applying pesticides.