“My advice (to farmers) is don’t turn your back on wheat midge, even if you are in a (low level) green zone on the provincial survey map,” says Tyler Wist, a field crop entomologist with Agriculture and Agri-Food Canada in Saskatoon.

“This is the biggest pest in wheat that we have in Western Canada and it’s not something that you want to take lightly.”

Wheat midge populations in Western Canada have been falling since the summer of 2021 when severe drought led to a significant decline in crop yields and a corresponding drop in the insect pest’s numbers.

That trend continued this past year. An insect pest survey conducted by the province of Saskatchewan showed significantly reduced populations of wheat midge in 2023 compared to 2022, although noteworthy hotspots were found north of Regina and some smaller dense populations were identified near Saskatoon, Kindersley and Lloydminster.

Alberta’s 2023 wheat midge survey results indicated a low population of wheat midge throughout the province, with the exception of a few fields in the Camrose and Edmonton regions.

Despite the declining numbers, Wist says producers should not be lulled into a false sense of security about the potential peril that wheat midge pose. Research has shown they can remain dormant in the soil for up to 13 years and can quickly become a concern again when an area receives normal or average rainfall levels.

“Thing can turn around pretty quickly,” says Wist. “They’ll come roaring back in a hurry if conditions are right.”

Full speed ahead

Now, he adds, is not the time for producers to take their foot off the gas when it comes to choosing midge-tolerant seed varieties.

“The best thing you can do is plant that midge-tolerant wheat because it’s there and it’s taking care of the wheat midge for you,” he says.

“You may be paying a bit more for it, but these days the midge-tolerant wheat is outyielding all of the midge non-tolerant wheat. The thing is, you never know when these insects are going to show up. We’re talking possibly 90 per cent yield loss in a field and that can happen in just a couple of days of females flying around in your field.”

Midge-tolerant wheat varieties were first developed by Agriculture and Agri-Food Canada following several major outbreaks of wheat midge on the Prairies in the 1990s. It’s estimated 32 per cent of all wheat now planted in Western Canada is midge-tolerant.

Such varieties have been available for the past 13 seasons. They contain a gene known as Sm1, which works by ramping up the production of phenolic acids in the seed when a midge starts to feed on it. The wheat midge doesn’t like the taste of those acids, stops feeding and subsequently starves to death.

Eileen Beaton, a crops extension specialist with the Saskatchewan government, says in a blog post several midge-tolerant wheat varieties are available for 2024, including varietal blends in CWRS, CPSR, CWSP, CWSWS, CWHWS, CHNR, CWES and durum wheat classes. A total of 36 varieties are registered and available for planting this season. More information on them is available online.

Another option to manage wheat midge risk is rotation to a non-host crop. Since spring wheat is the primary host for wheat midge, Beaton suggests producers consider planting a non-susceptible cereal crop such as oats or barley or a broadleaf crop such as canola or pulses, since midge adults are not strong fliers.

Difficult to detect

The wheat midge’s full name is the orange wheat blossom midge (Sitodiplosis mosellana). As its name suggests, it’s orange in appearance. It’s a member of the fly order (Diptera), although it closely resembles a mosquito because of its small size.

The adult wheat midge is not a threat to crops; rather, its larvae are. The adult female lays her eggs underneath a plant’s glumes, or leaf-like structures. Once those eggs hatch, the larvae tap into the wheat head’s developing kernel, causing the kernel to completely shrivel up and produce an unharvestable seed.

Part of what makes the wheat midge a formidable foe for farmers is that it can be difficult to detect until the damage has already been done.

“When it happens, you’re like, where did my seed go?” says Wist. “There’s no obvious exterior damage to the plant. You don’t see bites. You don’t see feeding damage.”

That’s why it’s important producers scout their wheat fields for the midge when it first emerges and is in its susceptible period, he says.

Wheat midge normally begin to emerge just before the Canada Day long weekend or soon after and emergence usually follows a significant rainfall. Growers, when scouting, should look for females crawling on heads in the plant’s canopy. The females generally lay their eggs at dusk or dawn when humidity is in the 60-70 per cent range and winds are calm. The economic threshold for yield is one female wheat midge for every five heads of wheat, which translates into a yield loss of about 15 per cent.

Three years ago, Wist teamed-up with SeCan, an independent seed retailer, as part of an initiative known as Midge Busters (#midgebusters on X). The project distributes pheromone traps to agronomists and farmers across Western Canada free of charge. Those traps are used to track the presence of wheat midge in farm fields and the data collected is then used to compare provincial midge forecasts with actual spring and summer emergence.

So, what causes some areas to become hotspots for wheat midge while other locations remain relatively untouched? Warm weather and precipitation are key factors, Wist says — but the truth is, much remains unknown about the pest and its habits.

“The pheromone trapping is something that I’m trying to continuously expand because more data is always better,” he says. “We can fill in those gaps in those areas to help determine what’s truly going on in some regions … like why is one region booming and another one isn’t?”

Diminished insecticide options

For farmers who choose non-midge tolerant wheat varieties, the number of insecticide options has recently diminished. Insecticides containing the active ingredient chlorpyrifos, such as Lorsban 4E, can no longer be used as they have been deregistered by Health Canada.

Beaton says some alternative insecticides such as Cygon and Lagon, which contain the active ingredient dimethoate, are available for use.

Wist says producers who use those products need to be extremely careful to apply them at the right time. If they are sprayed too late they will have little impact on the adult wheat midge or the eggs the females lay.

Those products can also cause harm to parasitic wasps known as Macroglenes penetrans, which are a natural enemy of wheat midge and help to keep their numbers low.

“It’s a really good predator of the wheat midge,” Wist says. “It acts by killing those over-wintering cocoons of the wheat midge. Not spraying for wheat midge too late helps to preserve populations of those parasitoids.”

The post Going, not gone: Some hot spots remain for midge appeared first on Grainews.

This year’s midge forecast isn’t bad. According to John Gavloski, Manitoba Agriculture entomologist, populations have been relatively low in the province over the last few years. But Gavloski still recommends scouting as individual fields could still see damage.

Midge scouting happens in a “very small window” in early July, he says. Wheat is only susceptible to midge from the time the head emerges from the boot to anthesis, after which the chemical profile of the grains changes and they are no longer an attractive host for midge.

Producers who get their wheat in the ground early may not have to contend with the pest at all, says Gavloski, if their wheat has already flowered by the first week of July.

“Later-seeded fields will be in that vulnerable stage — that will be the highest risk wheat, so producers should focus their scouting on those fields.”

Producers often find scouting for midge to be a chore as it has to happen around sunset, when the bright orange pest becomes active.

“The problem is our thresholds are all based on the number of wheat midge per head, so to really do a fair job of assessing if the field is at risk, you need to be out there counting adults per head.”

What to look for

Wheat growers wanting optimum grades should look for one adult midge per eight to 10 heads during the susceptible period. If you care less about grade and more about yield, drop the figure to one adult midge per four to five heads.

This math can be challenging in the field; midge don’t stay put once they’re out and about in the evening. Gavloski recommends focusing on a group of wheat heads rather than looking at just one or two.

“If you scout enough areas you’ll get a good sense of how abundant they are. If you’re having trouble seeing them you probably don’t have an issue,” he says.

When scouting, producers should keep an eye out for macroglenes penetrans, a small black parasitic wasp that naturally keeps wheat midge in check.

For most farmers, mid-tolerant varieties and good rotations are the best defenses. There are only two chemical options for controlling wheat midge, and both are Group 1B insecticides. The active ingredient chlorpyrifos is sold as Lorsban, Pyrinex, Nufos, Citadel, Warhawk, MPOWER, Krypton and pyrifos. The active ingredient dimethoate is sold as Lagon and Cyclon.

Scout your soft white wheat

When researchers found that the midge-resistant Sm1 gene occurs naturally in many varieties of soft white wheat, the industry immediately began asking soft white wheat growers to add a refuge of a soft white variety that doesn’t contain the gene (the variety AC Andrew). Adding this refuge will help ensure that midge populations don’t develop tolerance to the Sm1 gene, keeping our varieties of midge-tolerant spring wheat and durum viable for as long as possible.

Because this information came out a little late in the spring, many soft white wheat growers may not have had a chance to add a 10 per cent refuge of AC Andrew to their seeding plans. If this is the case on your farm, the Midge Tolerant Wheat Stewardship Team urges you to be especially vigilant in your scouting and spraying this year. – Leeann Minogue

The post Wheat midge 101: the basics of scouting appeared first on Grainews.

Researchers are still trying to find out more about the as yet unnamed midge species. “We’ve positively identified that it isn’t Swede midge, and we’ve looked at a lot of other described species. So far, it has not matched up to any of those so we are very certain that it’s yet to be described and is basically a new species,” says research scientist Dr. Boyd Mori of Agriculture and Agri-Food Canada’s Saskatoon Research and Development Centre. Mori first discovered the new midge in soil emergence traps. “We need one more field season to research it and maybe this fall we’ll have a name for it.”

Judging by what researchers have seen to date, they don’t believe producers should be too concerned about the anonymous midge, or Swede midge, another species that only began showing up in Prairie fields about 10 years ago, for the upcoming season.

• Read more: Want better insect surveys? Here’s how you can help

Last season’s warm, moist spring, which followed an exceptionally mild winter, provided ideal conditions for an explosion of Swede midge (and presumably the new midge species) across the Prairies. Crops emerged six to seven weeks early, favouring Swede midge, which has caused devastation in Ontario, where it can produce up to four or five generations, depending on conditions, in a single season. “We were definitely anticipating some surprises last season,” says Saskatchewan provincial entomologist Scott Hartley. “A warmer spring than we’d had for a while, and the much earlier emergence of crops provided a longer period of time for something that has multiple generations in a year to attack, and we expected to see more of the symptoms that we see in Ontario.”

Different factors on the Prairies

Thankfully, damage from Swede midge was minimal last year, leading researchers to surmise that the difference in climate on the Prairies — a generally shorter growing season and a cooler spring — could be limiting the number of generations to two or three and preventing both species of midge from becoming more damaging pests in canola.

The first year that Swede midge caused notable damage in Prairie crops was 2012, but it doesn’t appear damage from midge has increased since, so researchers are not sure if Prairie populations are stable. “We just don’t know what they need on the Prairies yet,” says Mori. “As part of a future study, we’re hoping to delve into the life cycle of both this new midge, and Swede midge, to try and determine whether populations are increasing, decreasing or stable and if it is likely to have an impact for producers. Right now, it doesn’t look like it, but if populations were to keep increasing, then every flower on the plant might be affected and if that happens, of course, there’s going to be some yield loss.”

Swede midge, from what researchers understand about its life cycle in Ontario, needs increased soil moisture, warm conditions and a rain event to prompt large emergence. Canola is highly susceptible to Swede midge through almost all growing stages, so with the long length of susceptibility, plus a large number of generations, it could have a dramatic impact on yield, as it often does in Eastern Canada. “The fact that we might only have two or three generations on the Prairies would definitely be helpful,” says Mori. “It would be less opportunity for it to attack canola, and cause less damage.”

A hard pest to control in Canada

There is as yet no economic threshold for Swede midge in canola, and current control strategies are limited.

The female midge lays her eggs on the actively growing tissue and when the larvae feed, they deform and crumple the tissue, and enclose themselves inside the tissue. So far, the only confirmed symptoms from the new midge species are bottle-shaped, galled flowers that form as a result of the larvae feeding inside the flowers. “That makes it hard for a contact insecticide to reach those larvae, so even if farmers spray they are not likely killing them,” says Mori. “It’s very difficult to time sprays to control adults, especially if we have multiple overlapping generations. Unfortunately, right now, controls in canola are lacking. There are two registered insecticides which have been used in Ontario for Swede midge, but as far as determining when to spray, that’s really up to the grower and agronomist to make somewhat of an educated guess to try and do it.”

Damaged flowers do not produce pods and seeds, but because there are a lot of other reasons why canola may not produce pods, including heat blasting or lygus bugs, it would be necessary to find the midge in the flowers to confirm they are the cause of reduced pod production.

Better management options for now, would appear to be planting as early as possible and longer rotations. “The faster farmers can get the canola crop to the early pod formation stage the better, because that’s really when it’s no longer susceptible to Swede midge,” says Mori. “Rotation is definitely key, as Swede midge can overwinter as pupae in the soil for longer than one year. If farmers have a short rotation, they may think it’s okay to grow canola one year, followed by wheat, and then go back to canola, but there could still be pupae from two years prior in that field that are emerging. Unfortunately, we do see a lot more short rotations on the Prairies, but if we could increase these rotations again, that would definitely have an impact on Swede midge populations and many other pests also.”

There’s also some hope for biological control. Researchers have found two species of parasitoid wasps in Saskatchewan that could provide effective, natural control for midge.

‘Right now we’re not sure if these wasps are parasitizing both the Swede midge and this anonymous midge, so we want to do more research to see which species they are attacking,” says Mori. “Last summer was the first year that they found parasitoids of midge in Ontario. They found one species and it’s not the same as either of the two species found in Saskatchewan. Swede midge has been in Ontario for over 20 years, so it’s quite interesting that it’s taken over 20 years for there to be a parasitoid there, but it’s taken less than 10 years for there to be parasitoids in Saskatchewan.”

Species could be native

The wide distribution of the new anonymous midge species and the discovery that there are parasitic insects for Swede midge already present on the Prairies makes researchers wonder if the new midge might be a native species that has developed new tastes. “It’s pure speculation at this point, but to this point we have found the anonymous midge on quite a wide scale. We found it all across northern Saskatchewan and throughout east and central Alberta. Given that it has this large distribution, I’m inclined to think it might be a native species that has switched, and taken the opportunity now that we have so much canola grown, to develop on canola,” says Mori. “It’s slightly supported by the fact that there are two parasitoids that might be parasitizing it. If it’s native you’d think that there would be some native parasitoids associated with it, so that could be supportive of the fact that it’s native, but we’re not sure. This summer we’re going to look at some of the brassica weed species to see if it is also developing on them in the field, and determine if they could be an alternative host, or maybe the natural host, for this midge.”

Mori emphasizes that farmers should remain vigilant, but not overly concerned about Swede or the anonymous midge for the present. “Luckily Swede midge was not an issue last summer, we didn’t find any, but perhaps the places we put our pheromone traps may not have had the populations there. They could have been a few miles down the road,” says Mori. “We advise farmers to be vigilant, and if they see large scale damage that looks like an insect pest, and that might be one of these midges, get in touch with us and we’ll help figure this out. Meanwhile, we’ll continue to research it and try and figure out if it will become an economic pest in the future.”

The post A new species of midge lands on the Prairies appeared first on Grainews.

Yearly scouting is needed to assess what pests exist in fields, as populations don’t always remain constant. For example, in 2016 there were higher counts of cutworm but lower incidence of Bertha armyworm. Diamondback moth arrive via winds from our Southern neighbours, and thus are very unpredictable. Flea beetles are usually present but damage depends on the effect growing conditions have on their development as well as ability of the canola crop to outgrow feeding damage.

Identifying pests can also help prevent future problems. Recently, a team of researchers from Saskatchewan, Alberta and Ontario identified a species of midge that is slightly different from the Swede midge. The Swede midge has caused major issues for canola growers in Northern Ontario, however the economic impact to Prairie canola growers, as well as the insect biology, is still being assessed. The new midge species is different physically and in DNA makeup, according to the research scientists at Agriculture Canada. However, the economic impact of this new species is not yet known.

Establishing a canola crop with good, uniform plant counts goes a long way towards minimizing pest impact. Well-fertilized crops allow for more rapid and even development and maturity. Proper rotations can also help to reduce impact.

For more information on insect identification, the Canola Council of Canada website (canolacouncil.org) has excellent information on pests and scouting

Doug Fehr is with DuPont Crop Protection Canada.

The post Midge scouting in canola appeared first on Grainews.

Researchers with Agriculture and Agri-Food Canada, the University of Guelph and the Canadian Food Inspection Agency have reported a new species of midge damaging canola crops in those areas.

The species “has yet to be named and scientifically described,” the scientists reported Monday on Alberta’s provincial Insect Pest Monitoring Network website.

The only confirmed symptom of damage so far from the anonymous midge is in the form of “bottle”-shaped galled flowers caused by larval feeding inside flowers, which then won’t produce pods or seeds, the researchers said.

Midge damage in Saskatchewan last summer “appeared to be low” in most fields, the researchers said, but the new midge’s full economic impact isn’t yet known. Swede midge in recent years were believed to be damaging Saskatchewan crops around Nipawin and Carrot River.

In Alberta, meanwhile, midge and suspected midge damage were detected last year from the Saskatchewan border around Lloydminister, westward to around Stettler and Smoky Lake.

Work is now underway to formally describe and name the new species, which the researchers said appears similar to Contarinia nasturtii, better known to growers in Eastern Canada as swede midge.

In Ontario, swede midge has been a known plant pest in brassica crops, such as cruciferous vegetables and canola, since 2000. It’s now “widely distributed” in both Ontario and Quebec and has also been seen in Nova Scotia and at least five U.S. states.

Crop scouts for years have noted differences between the Ontario pest and the Saskatchewan midge, researchers said, noting the type and amount of damage caused, the adult midge size and the number of generations per year.

Biologist and chemical ecologist Dr. Boyd Mori of AAFC’s Saskatoon Research and Development Centre also noted “extremely low” capture rates of adult swede midge in pheromone traps despite the “apparently high” rates of adult swede midge emergence.

With that in mind, Mori then collected adult midges and sent them to Guelph for study, where Dr. Rebecca Hallett and James Heal “immediately” noticed differences between the Saskatchewan and Ontario midge.

The Saskatchewan midge, the researchers said, “were more robust, had hairier wings and had slight differences in the antennae and genitalia” compared to the Ontario midge, they observed. Dr. Bradley Sinclair, CFIA’s midge expert in Ottawa, confirmed those differences and others.

Those differences, and DNA sequencing, have led to the conclusion that the Saskatchewan pest is a separate midge species, the researchers said. — AGCanada.com Network

The post Anonymous midge appears in Prairie canola appeared first on Grainews.

Midge threats in Alberta aren’t as high, but are more pronounced east of Edmonton and in the Peace region. However, Alberta Agriculture and Forestry warns that individual fields may have high economic levels, as variability from field to field has been high in the past.

The severity of the problem, Hartley says, will be dependent on climatic conditions. Wheat midge, he says, is favoured by moist conditions, so if we have a wet growing season, there’s a higher risk of wheat midge flourishing.

What can you do?

If you’re growing wheat (other than winter wheat), especially if you’re not growing some of the newer midge-tolerant varieties, you’ll want to keep an eye on the calendar.

“Late June to early July is usually the start of midge emergence across most areas, but this will depend on where you are” and the climate conditions, mostly temperature, says Hartley. During that key time period, monitor your fields. Ideally, says Hartley, “in the eve­ning to give you an idea what your midge populations are like. Usually we recommend one midge per four to five wheat heads as being a reasonable economic threshold, mainly for yield.”

If you’re looking for “top quality wheat, a durum or equivalent” for particular specialty markets, where buyers may have tighter standards, then one midge per eight to 10 wheat heads is what you’ll be looking for, says Hartley.

Pay attention to the “susceptible period, which can be affected by the timing of crop growth. Wheat is most vulnerable to midge damage as soon as the boot splits and any part of the head is visible until we see anthesis, which is flowering. If your plants get past the flowering stage and there’s no midge present yet, then the threat lessens because the plant has built up its natural resistance,” says Hartley.

Insecticides

If you’re above the economic threshold for the varieties you’re growing, you’ll want to apply an insecticide. Where there is variability within a field, Hartley says, you may be able to spot spray and “highlight certain areas and cut down on costs.” However, “in many cases it’s a case of full field spraying.”

Online resources

For risk warning maps and other information about all kinds of Prairie pests, visit the Prairie Pest Monitoring Network’s blog.

The site is updated throughout the growing season and includes wind trajectory updates and detailed information about insect pests.

The site is funded by the federal and provincial governments as well as a number of check off organizations.

Manitoba is not included in the wheat midge map, however, risk maps for other pests do include information about Manitoba.

The post Protect yourself against wheat midge appeared first on Grainews.