Adult diamondback moths have already been found in traps in several areas in Manitoba, which indicates the crop pest has arrived in Canada early this year.
In his Monday report, the Manitoba agriculture department’s entomologist John Gavloski writes that diamondback moths have been found in south-central, southeastern and southwestern Manitoba, and as far north as Teulon in the province’s Interlake region.
Numbers so far range from 18 in a pheromone trap at Emerson (south of Winnipeg at the U.S. border) to five near Altona and Carman, two at Hamiota (about 60 km northeast of Virden) and one at Teulon (about 50 km north of Winnipeg).
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Traps for diamondback moth are placed in fields, seeded or not, in early May to monitor when diamondback moths begin to arrive in the province, Gavloski wrote.
Conditions have been good over the past several days for survival and egg-laying, he wrote Monday, and with favourable weather ahead diamondback moth “could get off to an early start.”
According to the province, the severity of a diamondback infestation in a given year depends on two factors: one, overwintering populations to the south and two, strong south winds to transport the moths north into Manitoba, central Saskatchewan and eastern Alberta in the spring.
Among other noteworthy crop pests, flea beetle feeding is now common on volunteer canola across Manitoba, Gavloski wrote.
“This feeding is expected this time of year, particularly on hot and calm days,” he wrote. “Canola that has been seeded without a seed treatment containing an insecticide, and canola seeded in April, should be monitored for the amount of flea beetle feeding that is occurring.”
Also, he noted, volunteer winter wheat from three fields has tested positive for wheat streak mosaic virus: south of Brandon, near Somerset and near Boissevain.
Volunteer winter wheat must be completely dried or killed before spring wheat can be planted safely, Gavloski warned. Otherwise the risk is very high for wheat curl mites, which vector the virus, to spread into the spring crop.
Seven to 10 days of no grassy crops or grassy weeds are recommended to prevent live grassy plants “bridging” the mites to the next crop, he wrote.
