Each year we encounter volunteer corn in beans
It doesn’t matter if these are Roundup Ready soys, IP soys or edible beans, volunteer corn is a weed. It can decrease yield, interfere with harvest, result in IP beans being downgraded to crush beans and even have edible beans rejected because of “mud tag.” Mud tag occurs when a corn plant going through the combine has enough moisture to cause dust in the combine to stick to the beans as mud.
Ontario Ministry of Agriculture, Food and Rural Affairs publication 75, Guide to Weed Control, lists various treatments to control volunteer corn. Growers have found that many of these products control big corn plants. I have seen both Assure and Venture control volunteer corn that was tasselling. By the time corn gets that big it has already done a lot of yield damage. But there is another aspect to spraying late.
While there is no “Days to Harvest” advisory on these graminicides (post emergent grass herbicides) that control volunteer corn maybe there should be.
Once beans start to form pods graminicides that are sprayed on beans can be translocated to the developing bean. We have all heard horror stories of beans being shipped to a foreign country and then being subject to rejection because of residues. Some believe this is just a ploy by the buyers to get the price reduced. This may be true but at the same time is does not bode well for anyone. If the shipment is refused or sacrificed at a lower price the shipper and eventually the producer suffers. It is very probable that if a graminicide is sprayed late on developing beans that some of that herbicide will show up in the beans.
My suggestion is that you check for volunteer corn now and spray early not late. BF