You don’t like it when you leave one ear of corn behind, especially if it sprouts in the fall and helps turn the field green after harvest. Yet one ear of corn only has about 700 kernels. So, why would you let one waterhemp plant, capable of producing an average of 200,000 viable seeds, deposit its progeny in the perpetual weed seed bank?

“Preventing weeds from producing and spreading seeds is hugely important,” says Bill Johnson, Purdue Extension weed control specialist. “In fact, the importance can’t be overstated. The weed seed bank is like a savings account for weeds.”

So, what can you do yet this year to stop seed production? “If seeds are brown or black, they’re mature, and it’s too late,” Johnson says. “However, weeds like waterhemp keep producing seed until frost. There is still time to prevent some seed production.”

Your only practical choice in most soybean fields now may pulling by hand. However, Johnson suggests spraying fencerows, ditch banks, barn lots and even pastures to stop as much seed production as possible. “Of course, the best prevention is keeping weeds from growing in the first place,” he adds.

Longer-term prevention of weeds

What about in future years? Kevin Bradley, Extension weed specialist at the University of Missouri, has looked at other methods of limiting the seed bank for weeds that emerge and escape control.

Related:Why 2025 could be a good year for weeds

“We looked at mechanical means of destroying weed seed in studies several years ago,” he says. “These units are integrated into the combine, and while they don’t kill 100% of all weed seeds, they are very effective.”

Based on their results and other tests, they destroy the majority of weed seeds, Bradley notes. At least three models are currently marketed — two from Australia and one from Canada. While several growers use them in those countries, they haven’t caught on in the U.S. The big drawback is cost, with units listing at $70,000 to $80,000.

“If a major combine manufacturer works out an agreement and makes it an option you can order, and economics improve, they may get a closer look,” Bradley says.

Johnson adds that while he hasn’t tested a unit, he believes they may be more effective in places like Australia and even more western Midwest states rather than in the eastern Corn Belt, “Crop material is drier at harvest in those areas than here, and they likely work better on drier material,” Johnson says.

Weed control alternatives

Electrocution of weeds is also in use, primarily in some niche and specialty crop markets, Bradley says. “The concept works, and seed would be killed, but the equipment is nowhere near ready for use in commercial corn and soybean operations,” he explains.

Sprayers that use cameras to spray only weeds, like See & Spray from John Deere, also hold merit for knocking out weed escapes before they go to seed. However, cost is again a concern.

“Some sort of targeted approach, like targeted spraying or targeted electrocution, or else a check-box option for a mechanical method when you buy a combine is likely where we’re headed,” Bradley concludes. “The reality is we are just not there yet on a practical basis.”