Thousands, even millions, of tiny stowaways hide in the crannies of combines. Weed seed escapees on machinery are an inevitable reality, but you can reduce the damage.
NUMBERS GAME
The twin devils of the pigweed family, Palmer amaranth and waterhemp, produce prodigious seed; one plant can churn out 500,000 seed in Palmer and 250,000 seed in waterhemp.
When a combine rolls on the two, around 95% seed is retained until mechanically separated, says Daniel Smith, University of Wisconsin-Madison southwest regional agronomist.
“The vast majority of weed seed blows out the back of a combine, but I’d say 20% stays inside to be slowly dispersed back into the field, or in fields beyond, or on entirely different farms,” he explains. “This means there can be incredibly high numbers of seed hiding in a combine that drain a farmer’s pocketbook for years.”
CLEANUP TOOLS
Use a cordless electric leaf blower and a diesel-powered air compressor to clean, Smith suggests.
“Start at the combine’s front with the head on,” he says. “Blow out the head and grain platform because that’s where you’ll find tiny black seeds of lambsquarters or Palmer. You’ll spend 5 min. on a soybean platform and 15 min. on a corn head.”
Next, take the head off and clean out the feeder house.
“Blow it out, open any doors and blow them out and dump the rock trap,” Smith says. “Remember, safety is paramount, so wear a dust mask with a respirator rating, eye protection and ear protection.”
Roughly five more minutes finishes the task, according to Smith: “Walk around the machine and blow off the residue to help prevent fires, even though this residue does not generally contain weed seed unless it’s on top of the feeder house. That’s it.”
WHEN AND WHERE
If you roll through a particularly heavy patch of weeds during harvest, Smith recommends a cleaning.
“If weeds are sporadic, then clean after the field is done,” he says. “Even if a combine is used on separate land with the same weed species, the biotypes might be different, and that could cross different types of resistance.”
Where to clean? “A place where you know you can control weeds,” Smith says. “Maybe that’s a particular spot in a field or preferably at the shop.”
Smith estimates many growers cut roughly 6 acres of grain in 30 min. That same half-hour, devoted to a quick cleaning, can reap positive payback, he contends.
Chris Bennett is drawn to stories of innovation. He loves walking fields near his Mississippi home.
