Photo: Agriculture Canada
If you’ve been paying attention to the Okanagan Valley’s vineyards over the years, you’ve probably noticed they’re starting to look kind of scruffy.
While vines were once flanked by grass cut with golf-course-like precision, they are now often surrounded by scraggly, weed-like vegetation.
It’s not happening becuase vineyard owners have grown lazy, or are cutting landscaping costs. It’s happening because of a nasty pest called the climbing cutworm.
Tom Lowery is a research scientist at the Summerland Research and Development Centre. He explains that cutworms have been a “major pest” in the region ever since grapes were first planted here.
In the spring cutworm larva like to feast on budding grapes in vineyards. They hollow-out the buds before the grape can grow, causing some serious damage.
Gobbled-up grapes either don’t grow back at all, or grow back later than the rest of the crop, leading to ripening inconsistencies that affect wine quality.
Hans Buchler of Park Hill Vineyards has dealt with cutworms in the past. He says the severity of the pests can vary from year to year, but in the worst years the worms can damage 20-30 per cent of buds in a vineyard.
But Lowery has found a solution that appears to combat this problem pretty well, and it comes in the form of a couple of “weeds.”
Lowery realized that when plants commonly referred to as Shepherd’s Purse and Draba were in a vineyard there wasn’t much of a need to spray for cutworm.
After many nights picking through vineyards collecting worm in the light of his headlamp he discovered that cutworms liked to chow down on those “weeds” more than grape buds. But in a fascinating twist the “weeds” are actually toxic to certain species of cutworms, and will eventually kill them if they eat enough.
Armed with that knowledge he spurred vineyard owners to encourage growth of Shepherd’s Purse and Draba between their vines (even if they are a little less aesthetically appealing) to reduce their need to spray for cutworms.
Research into cover crops is still ongoing, but anecdotally Lowery’s method appears to be quite effective. He said cover crops planted at the research centre’s vineyard reduced the amount of cutworm damage so significantly it actually made it hard for him to collect enough data on their damage.
Buchler says for him the effectiveness of the method is tough to specifically quantify, but admits he’s seen cutworm damage reduced since allowing Shepherd’s Purse to grow in his vineyard.
“Ever since I’ve done this I certainly have had less damage from cutworms,” he says.
Of course, the one downside to what appears to be a pretty effective natural pesticide is a little more scraggle in the region’s once pristine vineyards.
“If you go around now you’ll notice a lot of the vineyards are shaggy looking, but that’s intentional,” Lowery says. “You don’t want it to look like a golf course anymore.”
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