Weeds that emerge prior to or during planting are the most threatening to soybeans. Weeds can reduce soybean yield by 1% per day if left uncontrolled after V2-V3 stages of soybean growth*. Starting with clean fields at planting is an essential part of sustainably managing weeds in soybeans and protecting your yields.
Tillage alone might not completely destroy established weeds. This can result in early weed competition as well as reduced herbicide efficacy. To remove early weed infestations, you must combine a burndown application with a residual herbicide tank mix or tillage.
2,4-D or dicamba may be required in burndown tank mixtures for tough-to-control weeds.
If emerged weeds are present at planting, a residual herbicide may be tank-mixed with Roundup® brand agricultural herbicides. There are various options to consider depending on the situation.
For best burndown efficacy, apply during optimum temperatures:
Day temperatures in the
high 50s to low 60s
Burndown applications should occur at least two weeks before planting to allow plant material to decompose. Refer to individual product label for all instructions, including plant-back restrictions.
Proper nozzle selection is important to both weed management and improved drift reduction. There are many nozzle types available, but the list below are approved nozzles based on Monsanto wind tunnel testing (Hewitt, U. of Queensland, August 2012) with experimental glyphosate and dicamba premix and tank mix formulations. These nozzles produce droplets in the very coarse to ultra coarse category.
AIXR - TeeJet
DR - Wilger
Air Max - Greenleaf
TDXL - Greenleaf
AI/AIC - TeeJet
TTI - Teejet
AI - TeeJet
ULD - Hypro
AITT J60 - TeeJet
Spraying weeds at 4 inches or less is the optimal time for maximum weed control. Although you can spray up to R1 in soybeans, that should not be the deciding factor on when to spray. Weed size is the key factor not soybean plant height of growth stage.
Spray weeds less than 4 inches tall
Maintain the required label buffer to protect sensitive areas
Make sure ground speed is less than 15mph
Use triple rinse tank clean-out procedure
Maintain boom height 20 inches above crop canopy
Apply when wind speed is between 3 and 10 mph
Use low-volatility formulations such as Roundup® Xtend™ and XtendiMax™, with VaporGrip™ Technology, upon their registration. Learn more.
Use spray nozzles and operating pressures that produce very coarse to ultra-coarse droplets to help minimize drift