Control of marestail in no-till soybeans
• can add Basis, or low rate of metribuzin or Canopy/Cloak to early-fall applications to control weeds that emerge later in fall, but this should not be needed from mid-October on.
• Do not overspend on fall treatments. Keep the cost of herbicides in the $6 to $15 range.
2. Apply effective burndown herbicides in spring. Do not plant into existing stands of marestail. Start weedfree at the time of planting by using one of the following preplant herbicide treatments, applied when marestail plants are still in the rosette stage. Note - tillage close to time of planting also effectively removes marestail, but must thoroughly mix the upper few inches of soil and uproot exisiting plants.
- 2,4-D ester plus glyphosate (1.5 lb ae/A)
- Saflufenacil product (Sharpen or Verdict) plus MSO (1% v/v) plus either glyphosate or Liberty
- 2,4-D ester plus glyphosate plus Sharpen or Verdict plus MSO (1% v/v)
- 2,4-D ester plus Gramoxone (3 to 4 pts/A) plus a metribuzin-containing herbicide
- Liberty (29 to 36 oz/A) or Liberty plus a metribuzin-containing herbicide
• The mixture of glyphosate and 2,4-D ester applied in the spring has become more variable for control of marestail over time, especially in fields that were not treated the previous fall. Plants should be newly emerged and no larger then the rosette stage at the time of application for best results. In fields where this mixture has previously failed to provide effective control, add Sharpen or use one of the other burndown treatments listed above.
• Control can be improved by using the highest rate of a 2,4-D ester product that is allowed, based on the interval between application and soybean planting. For all 2,4-D ester products, rates up to 0.5 lb active ingredient/A must be applied at least 7 days before planting. Rates between 0.5 and 1.0 lb/A should be applied at least 30 days before planting, with the the exception of several products (E-99, Salvo, and Weedone 650) that allow 1 lb/A to be applied 15 days before planting.
• Saflufenacil is a contact herbicide and effective activity is dependent upon use of the appropriate spray volume (at least 15 gpa) and nozzles, and the addition of MSO. Saflufenacil products cannot be applied in a mixture with other PPO-inhibiting (group 14) herbicides including: flumioxazin - Valor, Envive/Enlite, Gangster, Fierce; sulfentrazone - Authority products, Sonic; and fomesafen - Prefix, Vise, Torment. See label for most current information.
• In ALS-sensitive populations, the activity of any of the above can be improved with the addition of a herbicide that contains chlorimuron (Canopy/Cloak/Fallout, Valor XLT, Envive, Authority XL) or cloransulam (Gangster, Sonic, Authority First). The addition of metribuzin to any burndown treatment can also improve control of emerged marestail.