Pest that caused $1 billion in damage to US corn found in North Okanagan

Corn rootworms are a pest native to North America that causes severe damage to corn crops both in the larval state and in the adult stage. Western corn rootworms have been present in the Fraser Valley since 2016, but this is the first time they have been discovered in the North Okanagan.

Tracy Hebelschweizer, an entomologist with the Ministry of Agriculture and Food, told iNFOnews.ca that the ministry has been using pheromone traps and visual searches to scan crops for pests since the past seven years.

“August 2023 was the first time it was detected in the North Okanagan,” she said. “So, it’s brand new news. We know it’s in the Salmon Arm area and the Enderby-Armstrong area.”

More survey work will be done next summer to see if the pest infestation is more widespread in the Okanagan, Hueppelsheuser said.

Pests can actually cause significant damage.

Corn rootworms have been discovered in the North Okanagan and pose a threat to corn farmers.

Image credit: Kansas State University

“The damage is caused by the larvae that hatch in the spring from an egg that overwintered in the soil,” Hubelschweizer said. “So, the larvae hatches when the corn is young and feeds on the new roots of the corn, and the larvae destroys the roots… And obviously, if you flatten the rootstock, the plant can’t get as much moisture and nutrition. So it affects how well the plant grows.”

Once the beetles are fully grown, they can cause damage to corncobs as well.

“The beetle can also cause damage. “It’s a different kind of damage,” she said. “The beetle feeds on pollen, silk and leaves so it can affect pollination because it eats corn silk. If the silk is damaged, the corncob cannot be filled properly. Therefore the beetle can also cause some problems.

Unfortunately, these pests are not just a problem for corn farmers. Once the beetles hatch, they often migrate into gardens and begin feeding on late-season flowers.

“The caterpillar can only complete its cycle on corn. However, beetles can go to any flower, and they really like to go to watermelon flowers or dahlias. “They will actually feed on the flower and damage the petals… This is another way to monitor pests; And watch for beetles in late summer and fall flowers.”

Corn rootworms have been present in the Midwestern United States for 50 years, and in that time they have caused significant financial damage amounting to about $1 billion. This number represents the estimated loss in damage, but also the cost needed to control the pest, Hubelschweizer said.

“We’ve been lucky in British Columbia,” she said. “We have tools that have been developed in other parts of the world that we can use. Most of them are preventive practices. So, if you plan right and do everything you have to do, you won’t get any harm.”

An important step in corn rootworm prevention is crop rotation, Hueppelsheuser said. Since corn is the only host in which the insect can persist, farmers can destroy the pest by changing corn to a different crop for a few years.

“The most important and best way to manage corn rootworm is to make sure you weed your corn regularly,” she said.

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