A new look at an old invention could help potato growers beat weed competition – Potato News Today

Every now and then, an invention intended for one use is transformed into something else, and the resulting effect is far greater than its original purpose. Before becoming a groundbreaking medical invention for controlling heartbeats, the pacemaker was designed as a device designed to record rapid heartbeats.

In 2011, Agriculture and Food Canada (AAFC) scientists investigated ways to control populations of the European corn borer, a common potato crop pest that lays eggs in potato vines after harvest and matures the following year. To target the pest at its source, they developed a piece of equipment dubbed the “potato masher.”

The new equipment included two metal rollers, each attached to a motor connected to a speed governor powered by a 10 horsepower generator. It was designed to attach to the back of a potato harvester, and while harvesting the potatoes, the machine would crush the vines, killing the larvae of the corn moth.

The potato masher has successfully reduced the corn borer population. However, adult corn moths have wings that allow them to fly from one potato field to another. In order to control the population in a certain region, most if not all farmers will have to use this new equipment. Unfortunately, this all-or-nothing approach led to the demise of the potato masher.

The equipment sat dormant for 10 years until Charlottetown-based AAFC scientist Dr. Andrew McKenzie-Gopsill began working on a new idea in weed science called weed seed control.

“Weed seed control is when, at harvest, instead of returning the weed seed back to the field to grow and become a weed, the weed seed is harvested by completely removing it from the field or killing it directly in the field,” says Dr. Andrew Mackenzie-Gopsill.

Going against the grain

Dr McKenzie-Gopsill learned about the Australian-developed ‘Harrington weed killer’ – a towable unit on a combine that destroys weed seeds during cereal harvesting. In order to apply the concept of weed seed control to crops like potatoes, which are harvested differently than grains, he needs to think outside the box.

During a presentation at a local university, Dr. McKenzie-Gopsill was approached by a colleague at AAFC who helped develop the potato masher. They suggested that it could be used to crush weed seeds to reduce weed populations instead of its original purpose of crushing potato vines. Intrigued, Dr. Mackenzie-Gopsill decided to test the idea.

Without making any modifications to the potato masher, Dr Mackenzie-Gopsill decided to test the equipment in a simulated potato harvest by taking potato biomass from the field, adding weed seeds to the mix and sending it through the vine masher. He then placed the crushed weed seeds in petri dishes and soil to see how they grew.

Dr. McKenzie-Gopsill tested the equipment first on sheep’s quarter weed seeds, as this weed is the most economically important weed in potato production in Canada. He found that the vine crusher was very effective at crushing sheep’s quarter seeds, preventing them from germinating into full-grown weeds. Other types of weeds that infest potato crops were tested and they also failed to germinate. These included hogweed, meadow grass, yellow foxtail, and canola.

The results of the potato masher’s ability to reduce weed pressure were impressive for Dr Mackenzie-Gopsill and his team. In a controlled petri dish environment, seed germination, or the ability of crushed weed seeds to develop into weeds, was reduced by 60 to 95 percent. Simulated harvest resulted in a 50 percent reduction in germination of sheep’s quarter and pigweed, while other larger weed species reduced germination by 50 to 75 percent. Thus, a potato masher can also reduce the amount of herbicide used by farmers.

“We have developed the first ever weed seed control adaptation for a horticultural crop like potato. This is an exciting first step and has the potential to be a huge breakthrough in weed management for farmers,” says Dr Andrew McKenzie-Gopsill.

The economic solution continues to take shape

The potato masher’s simple, custom design makes it cost-effective for farmers, and Dr. McKenzie-Gopsill estimates it can be built for less than $10,000. He explains that while farmers can build and use it now, he intends to continue testing this summer to see how the equipment works in real field conditions. He will then make modifications to the equipment to increase its effectiveness in reducing weed seed germination or germination.

Dr. Mackenzie-Gopsill emphasizes the significance of his discovery by comparing his initial results with data published by American researchers over the past two years. They conducted simulations with Palmer amaranth, similar to pigweed, to determine how effective this type of equipment would need to be to have a long-term effect. They estimated that it would take a 20 percent reduction in weed seed germination to stabilize the weed population—the number of weeds would neither increase nor decrease.

“Our data shows in a simulated harvest that we have a much larger effect than a 20 percent reduction in non-invasive species like amaranth,” says Dr Mackenzie-Gopsill.

Key findings/advantages

• AAFC scientists tested the effectiveness of previously developed equipment, the potato vine crusher, to reduce common lambsquarters, red pigweed, pigweed, yellow foxtail and canola weeds in potato crops.
• In a controlled petri dish environment, seed germination, or the ability of crushed weed seeds to develop into weeds, was reduced by 60 to 95 percent. Simulated harvest resulted in a 50 percent reduction in quarter lambsquarters and pigweed germination, while other larger weed species were reduced by 50 to 75 percent. This equipment can also reduce the amount of herbicides used by farmers.
• Dr Mackenzie-Gopsill explains that although farmers can build and use it now, he intends to continue testing it in the summer of 2022 to see how the equipment works in real field conditions, and then make modifications to the equipment to improve weed reduction.

Source: Agriculture and Agri-Food Canada (AAFC)
Cover photo: Dr. Andrew McKenzie-Gopsill stands with potato crushing equipment at AAFC’s Harrington Research Farm. Courtesy of AAFC