A new, potentially damaging species of canola midge, the canola flower midge, was discovered in sticky traps last year in north central to northeastern North Dakota counties.
“We will be putting up pheromone sticky traps again this spring in May and June,” said Travis Prochaska, NDSU Extension crop protection specialist.
Prochaska said the canola flower midge is a brown-colored light fly, measuring less than 2 millimeters in length. Female wings are mottled with an identifying macrotricia.
Jan Knodel, NDSU Extension entomologist, and Patrick Beauzay, NDSU IPM coordinator and research specialist, authored a PowerPoint presentation to help NDSU Extension agents and IPM specialists know what information they do have about the pest from Canada.
According to the PowerPoint, the canola flower midge’s larva injures the flower by causing a swelling or gall that prevents the flowers from opening.
Damaged flowers will not produce pods or seeds.
Agriculture Canada found the midge in the Canadian Prairies in the 2000s, so it is considered relatively new to Canada, too.
“Canadian entomologists do not know the economic impact of the new Contarinia brassicola canola flower midge,” Knodel said in the PowerPoint.
Integrated pest management of the canola flower midge will include and has included: monitoring of the pest with the traps, planting date trials, insecticide seed treatments and yield loss studies.
Canada has started studying the canola flower midge based on the information found on the pest.
“It was found that early-planted canola in mid-May had more midge-damaged pods compared to late-planted canola in early June,” Prochaska said.
That meant early-planted canola had the highest yield due to other more important agronomic factors.
Insecticide seed treatments had little to no negative effect on midge injury to pods.
In 2016, Boyd Mori and colleagues in Canada discovered the canola flower midge in Saskatchewan and Alberta. The discovery of the canola flower midge also raised questions about the presence of swede midge.
“They had found a midge earlier and thought it was the swede midge. Now it looks like the discovery was probably not the swede midge, but the canola flower midge,” Prochaska said.
The swede midge is a brown fly that is small, from 1.5-2 millimeters in length, and has clear wings.
Hosts of the swede midge are canola, broccoli, cauliflower, cabbage, radish and other plants in the brassica family.
Hosts of the canola flower midge are canola and unknown hosts.
NDSU placed pheromone monitoring traps for the canola flower midge for the first time in seven northern counties in North Dakota in 2020.
Six of the 10 trap sites were positive for canola flower midge in five counties (see map).
Langdon Research Extension Center had the highest number of canola flower midge trapped with a total of 344 midges captured in 2020 during late July through the first week in August.