Farmer Invention Saves Tire Life, Crushes Corn Stalks

Stalk Knockers have no moving parts and do not require removal for trailer loading. “We are farmers just like our customers,” says Dave McGargill, right, alongside his brother, Kenny. “This is a simple and extremely effective way to save your tires.”

Stalk Knockers are a direct solution for a problem faced by corn producers. Combine and tractor tires often die the death of a thousand cuts, hammered by steady stabbing from corn stalks. Stalk Knockers, mounted just under the corn head on each row, serve as a battering ram to break stalks, essentially preserving tire life.

An innovation birthed directly in an Iowa cornfield by a pair of farming brothers, Stalk Knockers have no moving parts and do not require removal for trailer loading. “We are farmers just like our customers,” Dave McGargill says. “This is a simple and extremely effective way to save your tires.”

For Farmers, By Farmers

In 2014, McGargill was frustrated over wear on a front tractor tire: 75% of the bars remained, yet the cords were visible: “Basically, the tire was prematurely ruined and I was forced to buy a $1,700 tire replacement.”

McGargill and his brother, Kenny, are fifth-generation corn and soybean producers in the low hills of southwest Iowa’s Fremont County. When the pair began farming in the 1980s, corn stalks caused significantly fewer tire issues, McGargill says. “We’d put tires on tractors or combines and run them until the tread was worn and the tire was bald. Not today. Hybrids and corn varieties are bred so strong to produce more bushels and grow a stronger stalk. You can easily have a tire with 70% to 80% of its tread in place, but it wears out between the bars where the corn stalks stab the thinner part of the tire.”

STALK KNOCKER PLATE SUPERFLEX — “The Stalk Knocker plate busts the stalk open just above the brace root and starts the deterioration process. It’s a major, major tire saver,” McGargill says. (Photo courtesy of Dave McGargill)

In the winter of 2014, the McGargill duo designed a tire-preservation solution by mounting a steel plate under the corn head, just behind the snapping rolls. “We had looked at market products and didn’t find anything that would work because everything out there was mounted too far back on the heads.”

Trial-and-error tested in the harvest of 2015, the original 1/4” steel Stalk Knockers were born, dropping roughly 13” below the corn head with a bracket, and measuring approximately 10.5” tall and 10” wide at the very bottom. “The Stalk Knocker plate busts the stalk open just above the brace root and starts the deterioration process. It’s a major, major tire saver,” McGargill says.

Product in hand, the brothers immediately went to neighboring farms: “We put a set of Stalk Knockers on my uncle’s corn head, then a set on my neighbor’s, and just kept going,” he adds. “From there, we put them on Craigslist and had purchases from farmers in 13 states, and things just kept getting bigger.”

Rubber Poly

Installation for a first-time user requires less than an hour of time, according to McGargill. Simplicity is the hallmark of Stalk Knockers: “We focused on three keys for farmers. One, get the Knocker as close to the snapping rows as possible for going around curves and corners so it stays on the row. Two, make it so there is no need for removal during trailering. Third, no moving parts, period.”

JAMES DOYLE — “It’s been an awesome product for us because it knocks the stalks over as you combine, breaking them right above the root crown, and that means the stalks are so much easier on our tires,” says Iowa producer James Doyle. (Photo courtesy of Dave McGargill)

Originally made from steel, Stalk Knockers’ second iteration debuted in 2018—SuperFlex, a rubber poly version capable of bending 90 degrees without stress cracking. Almost 90% of current sales feature the SuperFlex version at $275 per row. The original steel version costs $98 per row, and a crossover (steel plate with SuperFlex bracket, interchangeable option) is available at $150 per row.

“We’re talking very little weight,” McGargill notes. “A Stalk Knocker only adds about 12 lb. per row.”

Pete Doyle, along with his parents, James and Melonie Doyle, grows no till corn and soybeans in southwest Iowa and use SuperFlex Stalk Knockers on a 780 John Deere combine with a 12-row header (split flex, hinged in the middle). “We started with the steel Stalk Knocker and have used the rubber poly for the last couple of years,” James Doyle explains. “It’s been an awesome product for us because it knocks the stalks over as you combine, breaking them right above the root crown, and that means the stalks are so much easier on our tires. Also, the stalks deteriorate much better when they are broken over, and that is very important when you no till soybeans into the corn stalk stubble the next spring.”

“The new corn hybrids are tougher on tires compared to the past,” James Doyle continues, “but this is a way to take away that wear factor, and we don’t have to take them off when loading on or off the head trailer."

“Real Value”

The original Stalk Knockers prototype took two years to travel from idea to market. McGargill advises any farmer with an invention, DIY effort, or innovation to trial the product in the field of another farmer. “If you really want to know what you’ve got, let your neighbor be your first customer. If your neighbor appreciates what you’ve come up with, then you know for sure it has real value.”

“As farmers, we’re relentless and don’t give up until we find perfection,” McGargill concludes. “We’re doing the exact same thing with Stalk Knockers and we’ll never stop trying to make improvement, because we’re proud to constantly try and make it even better for our customers.”

For more information, see stalkknockers.com.