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Research scientist develops device to manage corn borer in potato crops

European corn borers will soon be feeling the squeeze in Canadian potato fields. Dr. Christine Noronha, a research
scientist with Agriculture and Agri-Food Canada, has developed a piece
of machinery that, when attached behind a potato harvester, can help
reduce European corn borer (ECB) numbers.

The European corn borer control device is comprised of a series of brushes and metal rollers, which attaches to the end of the potato harvester. After the tubers are removed from the roots, the brushes catch the remaining plant debris and throw it onto metal rollers. The stems – with the ECB larvae burrowed inside  – are crushed as the plants go through the rollers. Contributed photo

European corn borers will soon be feeling the squeeze in Canadian potato fields.

Dr. Christine Noronha, a research scientist with Agriculture and Agri-Food Canada, has developed a piece of machinery that, when attached behind a potato harvester, can help reduce European corn borer (ECB) numbers.

In its adult form, ECB is a harmless light- to dark-tan moth. As apparent by its name, the corn borer’s crop of choice is usually corn, but it can also infect many vegetable crops, including potatoes. The female moth lays her eggs on the potato plant’s leaves and, after the eggs hatch, the resulting larvae burrow into the stems of the potato plants.

“These larvae feed inside of the stem and, while they are feeding, they weaken the stem and disrupt the flow of nutrients,” explains Dr. Noronha. “If the stems break and we get a wind, the damage can be widespread.”

This can result in reduced plant vigour and wilt, leading to smaller tuber sizes and decreased yield. As well, the established ECB larvae tunnels can become a route for the introduction of bacterial and fungal pathogens, such as black leg and tuber soft rot.

Once the cold weather arrives, the larvae overwinter within the plant debris left in the field after harvest. As temperatures increase in the spring, the larvae pupate and emerge as adult moths, ready to start the cycle again.

European corn borer has been a problem for some potato growers in Canada for many years and is traditionally controlled through well-timed, broad-spectrum insecticide sprays. But after consulting with growers and investigating the insect’s life cycle, Dr. Noronha, who specializes in best management practices aimed at reducing pesticide use, discovered there’s a small window of opportunity to reduce ECB numbers by crushing them just as the eggs hatch and the larvae burrow into the potato stem.

The device is comprised of a series of brushes and metal rollers, which attaches to the end of the potato harvester. After the tubers are removed from the roots, the brushes catch the remaining plant debris and throw it onto metal rollers. The stems – with the ECB larvae burrowed inside  – are crushed as the plants go through the rollers.

The female European corn borer moth lays her eggs on potato plant leaves and, after the eggs hatch, the resulting larvae burrow into the stems of the plants. This can result in reduced plant vigour and wilt, leading to smaller tuber sizes and decreased yield.  Photo courtesy of USDA-ARS

When developing the machine, Dr. Noronha wanted it to be user-friendly and involve a management practice already being done, meaning growers wouldn’t have to cover the field a second time.

“I wanted to make something that could adapt to the harvesters,” she says, adding, “We also wanted it to be economical.”

As such, the resulting attachment, built with the assistance of Brian Weatherbee, a welder and shop manager with Entire Manufacturing Metal Works of Stratford, P.E.I., can be operated through most tractors’ standard hydraulic systems.

It took a couple of months and about $8,000 to $9,000 in expenses to move from a sketch of the basic concept to an actual working mechanical device.

“It’s very reasonable, compared to other farm machinery,” says Dr. Noronha.

Once the prototype was built, the device was put into use. “We can’t just build it and say it works,” explains Dr. Noronha. “So we did an efficacy trial … to show numbers.”

In the first trial, the stems were crushed and taken back to the lab to determine just how many ECB larvae had died. “About 87 per cent of the larvae died (with the crushing),” says Dr. Noronha, but she adds that many of the stems shattered, meaning some of the larvae may have fallen out.
 
“We thought maybe the winter would kill them, but to prove that, we left crushed and uncrushed stems in the fields all winter,” she explains.

In the spring, the stems were collected. About 300 moths were found in the uncrushed stems while about three were found within the crushed stems.

Following some fine-tuning, a second trial was held, resulting in an even better kill record. At that point, Dr. Noronha decided to take her machine to the P.E.I. potato industry for a demonstration.

“The growers were very interested.” Dr. Noronha has received inquiries from potato growers throughout Prince Edward Island and New Brunswick.

Brian Weatherbee’s machine shop is investigating putting a kit together to help growers build their own device to fit their particular harvester.

“We would like them to be able to build it themselves, otherwise they would have to bring the harvester to our shop,” he says. “It really would be more cost effective to have a kit.”

There is no patent on the attachment and other metal works shops are free to build the device, if they wish. “If we had a request from two or three growers, we would be able to build that many,” Weatherbee adds.

“The machine is very simple to build,” says Dr. Noronha. “Every single piece can be bought separately and locally.  You can custom build it for your own harvester.”

There can be some fiddling involved when putting the device together, as far as placing the roller and springs is concerned. “They (the rollers) have to be well-placed with the springs on them,” explains Dr. Noronha. “Then, if you end up with a rock, the rollers just open up and let the rock fall out.”

Dr. Noronha believes her attachment is a great alternative to spraying and, while it might not eliminate all ECB the first season, it will get them in the second year, all without the grower needing to chemically treat the potato crop.

“Anything that reduces the use of chemicals is good for the farmer and the environment,” she says.