Spreading weeds this harvest isn’t on anyone’s to-do list, but your combine could be doing just that as you travel from field to field. Albeit unknowingly, your combine could be harvesting – and carrying – thousands, even millions, of weed seeds. A University of Wisconsin-Madison agronomist says one pigweed plant can produce half a million seeds. Agronomist Daniel Smith says of those seeds, 20% are estimated to stay inside the combine and disperse back into fields.

What’s the solution? A good old-fashioned wind bath. Smith suggests blowing out the combine’s front, head and grain platform using a leaf blower because that’s where most of the seeds will be. He says it should take about five minutes on a soybean platform and 15 minutes for a corn head. Cleanings are recommended when a field is done and should be completed in a place where you can control weeds, like at the shop.

Read more on combine clean-up efforts here.