Source: Penn State Extension, D. Lingenfelter
Penn State weed science extension along with other university weed scientists recommend using dicamba (Xtendimax, Engenia, FeXapan) primarily for burndown in “full-season” Xtend soybeans. In-crop or post applications as well as, burndown in double-crop soybeans can be risky. Post applications usually occur when many sensitive crops are very susceptible to dicamba and weather conditions favor dicamba drift. However, if post applications must be used for controlling problem weeds such as Palmer amaranth, escaped marestail, or persistent perennials, make sure to use caution and be aware of surrounding crops and sensitive areas. The applicator is responsible for drift and its consequences.
Assuming you have taken the proper training, here is a primary checklist of things to consider if you must apply an approved dicamba product in Xtend soybeans at this time of year:
- Only use nozzles, adjuvants, and tankmixes that are approved for dicamba application (see product website links below for more details)
- Never use AMS (ammonium sulfate) or other acidifying additives in the spray mixture
- In some cases, a DRA (drift reducing agent) is recommended to help minimize fine-droplet drift
- The spray volume must be >10 gallons/acre but 15 to 20 gpa is best
- Don’t spray when winds are <3 mph and >10 mph
- Keep the boom no higher than 24” above the target
- Only spray during the daylight hours from sunrise to sunset and be cautious of temperature inversion conditions during the evening and over night
- It is best not to spray if air temperature is >85° F
- Never spray if wind is blowing towards neighboring sensitive crops
- Weeds should be no taller than 4 inches at application
- Make sure to properly clean out the sprayer immediately after application
- Complete necessary record keeping about the spray application
Refer to their labels and websites for additional information and updates online by Monsanto, by BASF, and by DuPont.