n THE CARILLON STEINBACH, MAN. C4
n www.thecarillon.com THURSDAY, FEBRUARY 22, 2024
Look what the wind blew in
Adult two-striped grasshoppers.
JOHN GAVLOSKI
stage until next spring. But that egg is closer to hatch than it would have been in a cooler fall. So, the hatch might occur quicker next year.” There are a few naturally occurring things that can hamper grasshopper egg growth, such as predators like bee flies, blister beetles, ground beetles, and field crickets. In terms of winter mortality. Gavloski says don’t count on it. “Soil temperatures of -15 de- grees, about two to three inches into the soil are required to cause substantial winter mor- tality.” This depends on snow cover since eggs are usually laid where snowfall accumulates. “Even an inch or two of snow is enough to in- sulate them.” If spring is too dry, it can delay hatch. Grass- hoppers need a bit of moisture for hatch, but not a lot. Temperature is what drives the cycle. “Scout your ditches and field edges, and ar- eas where grasshoppers tend to emerge in your region, starting in early June. That’s when you can probably expect to see the hatch starting.” Burning won’t kill the pest species of eggs. “It might blacken the area, so that a hatch might occur quicker. Mowing ditches may also cause them to spread to the crops.” Armyworms Armyworms are in the same family as the cutworm, Gavloski said. “If you poke them, they’ll curl into a ball, and you can often find them in patches in the field. These are ma- jor pests. They migrate north in springtime, like butterflies. We had some very high levels last year, in late June and July, right across the province.” Armyworms like dense grassy vegetation to lay their eggs, so scouting for them isn’t diffi- cult. “If you have areas that are denser, espe- cially a cereal crop, check those areas carefully. We do monitor and set traps for these adults, and we can give you at least a bit of advance notice if we see them in our traps.” Shake the plants and look on the soil for armyworm larvae. During the day, also look under plant debris, lumps of soil, and in soil cracks where they may hide. In cereal and grass crops, check at least five areas of a field, starting in late June. Pay special attention to patches of lodged plants and areas of grassy weeds. Any field in areas that have significant bird activity should be scouted. Also check the backs of armyworms for par- asite eggs. Natural enemies of the armyworm are Cotesia wasps, who lay eggs into the army worm. Diamondback moth The Diamondback moth is blown in by strong south winds into Manitoba across East- ern, Interlake, Central and Northwest regions in July and August. Their numbers are hard to predict. Mani- toba Agriculture puts up traps for them. Last year, they had 84 traps set up at different loca- tions, with a monitoring period generally from May 1 to July 1. “It can vary from year to year. The numbers were extremely high in the Alto- na and Horndean areas last summer,” Gavloski said. Few, if any, survive winters in the Canadian prairies. “When they move in and get established, the pod feeding is the most damaging. If you have good soil moisture and they’re feeding on flowers and buds and things, usually plants like canola will produce more flowers and buds and compensate for that feeding. But the plant can’t produce more pods and seeds once it gets to that stage. The pod feeding is really what we want people to watch out for.” Aphids in cereals “Aphids were a concern and are also some- thing that blows in on the winds. They were an issue in quite a few regions. Probably more so in the western part of the province and the central region. The problem we ran into last year was they came in quite late, well into July. People were scouting and they weren’t quite at soft dough yet. They were still in the suscep- tible stages. But spring was an issue because we’re limited to two registered active ingredi- ents: malathion and dimethoate.” Dimethoate has a 35-day preharvest inter- val. “So, when you’re almost at soft dough, that’s not an option. And malathion wasn’t all that readily available. It’s an okay product on aphids. Dimethoate is probably the better product in the long run, but because of the long pre-harvest, it’s not an option.” Aphids have lots of natural enemies (such as lady beetles and aphid mummies) in some fields. Last year, there were above-threshold aphid numbers, but they also had a lot of lady beetles, and parasitized aphids. Farmers didn’t
by LORI PENNER J ohn Gavloski is a fascinated observer of almost any type of wildlife, with a particu- lar interest in all the creepy, crawly visitors that not only harm your crops, but also benefit them. Based in Carman, with a Ph.D. in entomolo- gy, Gavloski has been working with Manitoba Agriculture since 1997, monitoring and pro- viding information on insects that are both beneficial and potential pests to farmers, agronomists and those working with agricul- ture. He also conducts numerous presentations and information updates for agronomists and farmers and co-produces a weekly Manitoba Pest Update during the spring and summer. In a recent presentation, Gavloski listed the top 10 insect concerns that producers faced in 2023, offered a forecast for next year, and pro- vided scouting and management tips for the 2024 growing season, as well. The top 10 list included: flea beetles in cano- la, grasshoppers, armyworms, diamondback moths, alfalfa weevils, cutworms, aphids in small grains, field peas and soybeans, and Ly- gus bugs. “Fleas beetles, grasshoppers and army- worms were major insect concerns in every agricultural region of the province,” Gavloski said. “The others were of concern, but more localized and weren’t as widespread. Five of those 10 are things that overwinter well here, and five either blew in or migrated in. So, flea beetles, grasshoppers wintered well. Army- worms migrate in a purposeful migration. Dia- mondback moths don’t winter well; they blow in. The alfalfa weevil doesn’t winter as well as cutworms. Pretty much all aphid species, if they’re going to be a problem, it’s because they’ve blown in.” Flea beetles in canola Gavloski says last year resulted in many is- sues with flea beetles. “They were widespread. But it wasn’t as bad as the year before. What puts you at a higher risk for flea beetles is sit- ting and not growing quickly early on.” Producers were treating canola seed with neonicotinoid seed treatment, and many fields received additional insecticide applica- tions. There were also heavy feeding or insecti- cide applications reported from all agricultural regions. “In some areas, uneven emergence and vari- ability in stages made scouting more compli- cated.” Gavlioski said slow emergence and delayed early season growth makes canola more vul- nerable to flea beetles. “The challenge is to get the canola plants to a stage where they can naturally tolerate flea beetle feeding (3-4 leaf stage) without signifi- cant feeding injury.” Last spring’s excellent growing conditions and warm soil resulted in quick germination and emergence in some areas. Cultural controls for flea beetles in Canada include planting seed as shallow as available moisture will allow. Direct seeding also pro- vides a microclimate which is less ideal. Flea beetles prefer environments exposed to bright sunlight which are relatively warm. “In- creasing seeding rate and seeding into cooler soil can also minimize the damage in some of the fields,” he said. “The tricky part is if you see treatments are wearing out, you’re still not at the 3-4 leaf stage. Sometimes you have to make that decision: do we spray, or don’t we spray? That can be really tricky.” Producers could also consider stem cutting. “But there’s an art and a science in scouting for females. We’re factoring in a variety of things, so you really have to use a bit of intuition and common sense in your decision making.” Grasshoppers “In our areas, there are many different crops, so some farmers don’t have to deal with them in any significant way. Other farmers do. So, it can vary within a region.” There are roughly 85 different species of grasshoppers in Manitoba, with 180 species in Canada. Four of those species are considered pest species. “It’s good to know which species you’ll find in your area.” Pest species can lay a lot of eggs, and Gavlos- ki says if you get them in early frost, sometimes it cuts down the egg laying before they get a chance to lay their maximum amount. “Last year, the frost came quite late, and they were able to lay their maximum numbers. They were in warm enough conditions, so they were quite active. If you get a warmer extended fall, there is embryonic development happen- ing in those eggs, so things will stay in the egg
JOHN GAVLOSKI
THARSHI NAGALINGAM UNIVERSITY OF MANITOBA
Oat-birdcherry aphid.
Adult Lygus Bug.
MANITOBA AGRICULTURE
Diamondback moth pupa and larva.
beans, and high levels in rye and wheat.” The new economic thresholds for Lygus bugs in canola suggest a threshold of 20-30 per 10 sweeps for good growing conditions. Using the lower end of the threshold (about 20 per 10 sweeps) may be appropriate for stressed cano- la with less ability to compensate for feeding. The most vulnerable crop stage for Lygus feeding is when seeds are enlarging on lower pods. When most pods become “leathery” and when seeds inside are firm, Lygus bugs can no longer penetrate the pods or seeds with their mouthparts and are no longer an economic threat. For more information on insects, go to the Manitoba Agriculture website.
really want to spray because there were a lot of good guys. There is an app where you can factor in a lot of the natural enemies, and it will adjust a threshold for you. But you do have to scout five areas of the field and several plants per area so it can make a decision for you. There are no shortcuts.” Lygus bugs Lygus bugs are sap feeders, with a beak like a mosquito. They suck the juice from the plant, and like to feed on nitrogen rich newer growth, like flowers, buds, and seeds. “They can be- come a real problem when they’re feeding di- rectly on your seeds and will do this with a lot of plants. Last year we had issues in canola, dry
LORI PENNER THE CARILLON Gavloski listed the top 10 insect concerns that producers faced in 2023, offered a forecast for next year, and provided scouting and management tips for the 2024 growing season.
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