Burndown with residual in Soybeans.
Recently we have received quite a few calls on using a burn-down in soybeans.
In the past these questions mostly came from patrons who no-tilled soybeans. This spring, the unusually warm early temps have geminated a lot of broadleaves (especially lambsquarter), both in tilled and untilled fields which many are 4 inches in height or larger as of the writing of this article. If you are planning a single tillage pass this spring it’s highly likely that a fair % of these weeds will survive that tillage pass or even multiple passes) because of their size. The HLC test plot at springfield looks very similar to a lot of fields I see in the area with a lot of 4” plus emerged weeds. On Monday the 30th I sprayed a few short burn-down applications and included the pictures below at 3 days after application.
Picture #1 (below) shows the difference between Sharpen 1 ounce with no additives (not recommended) and sharpen with MSO and AMS added. As you can see in the picture, the additives (MSO 1 pint/acre and AMS 1.5#’s/acre) are needed on emerged weeds to achieve satisfactory control.
Picture #2(below) shows the difference between a Roundup only application (22 ounce)s on right side- vs- adding Sharpen at 1 ounce to the roundup applicaton. Glyphosate applications alone are much slower acting and can be erratic in cool temperatures and also any disturbance to weeds within 7 days of application can cause emerged weeds to shut down and stop uptake of glyphosate, causing poor weed control.
Picture #3 (below) shows the glyphosate application alone (22 ounces) on left – vs- an application of 2-4D Ester (6 ounces) on right side. Note that an application of 2-4D Ester requires a minimum of 5 to 7 days after application before planting.
Advantages/Disadvantages and pre-cautions with each herbicide
**Sharpen – Very fast knockdown of broadleaves including residual control. No grass activity (the addition of glyphosate provides grass control as well as help with troublesome weeds like dandelion). Do not apply sharpen after crop emergence or injury may occur .
**Glyphosate brands- Broad spectrum control, but without residual and can be erratic in cool temperatures. Also requires a 1 week waiting period to achieve acceptable weed control.
** 24-D Ester – Provides broad-leaf control but with no residual or activity on grass. Also requires a mandatory 5 day minimum waiting period before seeding/ planting or injury can occur.
- Remember to always read and follow manufacturers label before applying herbicides.