Entomologist warns sunflower growers to take a close look before spraying

Something bugging your sunflower crop? Or just bugging you?

Separate sunflower friend from foe before spraying, a provincial government entomologist reminded producers at the annual Special Crops Symposium.

“Ground beetles can destroy as much as 40 per cent of the sunflower beetles’ larvae over the winter, they’re important … and significant,” said John Gavloski. “It’s good to have them.”

The humble ground beetle, also known as the carabid beetle, isn’t alone in its culinary tastes. At least five species of parasitic wasps also feed on the larvae of sunflower pests, noted Gavloski.

And despite its name, the minute pirate bug is also one of the good bugs. It attacks and feeds on instar eggs as well as some larvae.

But the banded sunflower moth, sunflower beetle, lygus bugs, midge and red sunflower seed weevil continue to require vigilance, said the entomologist.

“Sunflower midge may be increasing, or it could be, depending on the weather,” said Gavloski. “They like early moist soil, so another wet spring could make it an issue.”

The banded sunflower moth may also increase in the coming year, although trap levels varied from field to field in 2011, he said. However, seed weevils remain at low levels in most areas of the province and aren’t expected to be a major issue in 2012.

Late planting can reduce the amount of damage caused by the banded sunflower moth, but there is a trade-off because damage by red sunflower seed weevil is slowed by early planting, Gavloski said.

“So you need to consider what is the biggest risk in your area and plan ahead,” he said.

What type of sunflower you grow is also a factor. Gavloski noted 10 to 12 weevils per plant is the threshold for treating oilseeds, compared to one to two per plant for confection seeds.

As with all pesticides, farmers need to take the honeybee population into account.

“Sunflowers will self-pollinate to some degree, but if you have a good honeybee population you will have a higher yield,” said Gavloski.

He added that using less toxic pesticides should be considered, noting less toxic doesn’t necessarily mean less effective.

The entomologist also suggested producers spray late in the evening when fewer pollinators are out.

About the author

Reporter

Shannon VanRaes is a journalist and photojournalist at the Manitoba Co-operator. She also writes a weekly urban affairs column for Metro Winnipeg, and has previously reported for the Winnipeg Sun, Outwords Magazine and the Portage Daily Graphic.

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