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iN VIDEO: Tending grapevines isn't just a daytime activity

PENTICTON - There’s a perennial pest that invades Okanagan vineyards in early spring that, if left uncontrolled well... might not ruin the year’s vintage, but will certainly result in less of it.

I’m talking about the climbing cutworm, which Summerland Research and Development Centre research scientist Tom Lowery says is among the Okanagan and Similkameen valley’s top three most important insect pests of grapes.

In addition to reporting for, I live on a small acreage in Kaleden and have a small ‘hobby’ vineyard of my own.

Over the past week or so I have learned something about the climbing cutworm the hard way after a neighbouring vineyardist told me, with some surprise, he found cutworm on his vines.

I checked my own plants and was also surprised, and dismayed, to collect more than 170 of them after about a week of inspecting roughly 700 vines.

Great. My small, non-commercial operation usually has a single employee, who’s also the boss.

I could use chemical sprays to control the pest, but as Lowery notes, his research and many growers’ interest these days is more towards finding alternative management strategies more compatible with sustainable and organic wine grape production.

Unfortunately, the organic control method involves patrolling the vineyard after dark, inspecting the canes with a flashlight because the cutworms feed at night. Once the lights are out, they make their nocturnal commute up the vine trunk to the cane, where they head for the developing buds.

Small worms will burrow into buds, while larger cutworm will chew large ragged holes and remove a portion or all of the bud. They also feed on new shoots, causing them to break or wilt.

They are quite easy to find this way, crawling up the cane or chewing on a bud. Once found, they can be easily collected in a container and disposed of.

Cutworms can't be counted on to cause a lot of damage, as the pest's location and devastation vary widely from place to place and year to year.
Cutworms can't be counted on to cause a lot of damage, as the pest's location and devastation vary widely from place to place and year to year.

Are grape growers facing an infestation of cutworm this year? Lowery says its too soon to say, but I’m pretty sure I am.

The cutworm lays eggs in fall and spends the winter as larvae. In spring they grow quickly, feeding on developing buds.

Lowery says the pest and the damage inflicted on a vineyard can be highly variable, with damage levels varying greatly from vineyard to vineyard and region to region.

“The year to year variations aren’t understood, but weather may play a factor. A warm, long fall might result in more eggs being laid,” he said in an email earlier this week.

Lowery also said grape vines and cutworm larvae also have slightly different development thresholds and the peak in larval feeding and growth might not always align fully with the time when the buds are most vulnerable.

Buds are in varying stages of maturity throughout the Okanagan right now, so it’s hard to tell whether cutworm activity is abnormally high or not, especially when  the variability factor for populations and damage is taken into account.

Inspection is key at this point, Lowery says. Checking the vines are critical because damage can increase rapidly when temperatures are warm,

Environment Canada is forecasting temperatures in the 20s and sunny days into next week.

I guess I know where I’m going to be after dark.

Are you a grape grower experiencing similar problems with cutworm this year? Please let us know.

To contact a reporter for this story, email Steve Arstad or call 250-488-3065 or email the editor. You can also submit photos, videos or news tips to the newsroom and be entered to win a monthly prize draw.

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