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Pre-harvest Application Timing for Beans and Soybeans

Getting a few questions for preharvest burndown applications for edible beans and soybeans. The first white bean applications will likely be the first week of September. The first soybeans are starting to turn and drop leaves which puts the first soybean harvest approx 4 weeks away. Some reasons to consider preharvest applications even in Roundup Ready soybeans:

  • to be able to harvest 1-3 days sooner than if no burndown by having a ripe, even crop.

  • to increase combine efficiency by not fighting weeds and green stems so harvest more acres per day.

  • earlier wheat planting with less pinning of residue by drill.

  • perennial weed control of Thistles and milkweed which have made a comeback due to last years drought.

  • residual fall weed control for winter annuals like chickweed and resistant fleabane.

  • sometimes will not need further weed control in your wheat crop.

Typically I recommend the standard rate of glyphosate ( 1 Litre equivalent) plus Eragon LQ @ 30 mL/ac with Merge @ 400 mL/ac in 20 gallon of water. The Eragon rate can go up to 59 mL/ac under cool, wet overcast conditions for better activity. Applications work best when applied in the early morning on a sunny day. This is applied approx 10 days preharvest. The timing to look for is 90% of pods have turned colour from green to yellow as they mature. Leaf colour or drop is not a factor when determining timing, always go by the pods. I know some IP contracts are offering additional premiums for beans with no preharvest applications. This is a trade off that will be field specific based on how weed free your fields are. No sense risking the full IP premium in order to get the smaller top up premium.

You are welcome to contact Emma, Chris or myself for assistance too.


Deb Campbell CCA-ON, 4R NMS

Agronomy Advantage Inc.


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