Purdue's Bill Johnson and Mark Loux, Ohio State University Extension weed control specialist, have prepared recommendations for marestail control in soybeans. Here are key highlights from their recommendations.
• Best spring control of emerged maretail is in rosette stage. Fall-emerged plants bolt quicker in the spring.
• Tillage is effective if you thoroughly mix the upper few inches and uproot existing plants
• Never plant into existing marestail. Burndown options include 2,4-D ester plus glyphosate; a Saflufenacil product, like Sharpen or Verdict, plus an MSO plus glyphosate or Liberty; 2,4-D ester plus glyphosate plus Sharpen or Verdict plus MSO; 2,4-D ester plus Gramoxone plus metribuzin; or Liberty with Cheetah, where metribuzin improves control.
• Liberty over Liberty Link soybeans is the most effective marestail control strategy. Apply Liberty/Cheetah at 29 ounces per acre before plants exceed 6 inches tall. You can go to 36 ounces on taller plants, but control is variable.
• Glyphosate and 2,4-D ester alone isn't consistent. Add metribuzin and/or Sharpen, or one of the burndowns above.
• Improve control by applying the highest rate of 2,4-D allowed. Check label for restrictions on interval between application and planting
• Adding dicamba to spring burndowns delivers better control than 2,4-D, but is more damaging to soybeans if you don't follow guidelines. Clarity label specifies a 14- to- 28 day interval, depending upon rate and rainfall.
• Include residual control with burndown. Residual options include: flumioxazin (Valor, Valor XLT, Envive/Enlite, Fierce, Fierce XLT, Gangster/Surveil. Trivence; sulfentrazone (Authority First, Sonic, Authority XL/MAXX, Authority, Authority Assist; metribuzin: Metri DF, Tricor, Glory, rate based on soil type; addition of metribuzin to products already containing metribuxin, such as Boundary/Ledger, Canopy/Cloak DF, Intimidator, Matador and Authority MTZ.
• If marestail is ALS-resistant maximize use of flumioxazin, sulfentrazone or metribuzin. Consider mixtures with two non-ALS products.
Related: Thoughts About Controlling Marestail
Learn more in the 2015 Weed Control Guide for Ohio. Order at 614-292-1607.