There are two main insect pests of wheat that keep breeders busy: the wheat stem sawfly and the wheat midge. There is resistance to each and effective predators of each, but the insects still manage to eat a significant amount of wheat yield each year.
To unpack how these two pests cut yield, quality, or complicate harvest, this episode of The Agronomists features Agriculture and Agri-Food Canada entomologist, Tyler Wist, and Alberta Wheat and Barley’s, Jeremy Boychyn.
This episode of The Agronomists is brought to you by ADAMA Canada, Wheat Pete’s Word, and the Wheat School!
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- Let’s start with midge!
- The forecast for 2022 in Saskatchewan and Alberta was really not bad
- But….the eventually numbers climbed to very high levels in some areas
- Thank you to farmers and researchers and SeCan for being willing to trap and count midges — #MidgeBusters
- Midge emerge from the soil after a good rain
- Pheremone traps males and alerts you to go scout for females in the crop
- One midge per five wheat heads requires action if not using a resistant variety
- Surveys done in the fall count larvae in the soil to build the forecast maps
- Low risk areas don’t mean no risk!
- Midge feed on kernels and cause yield loss and downgrading
- Keep scouting, even if in a low risk area — don’t be complacent
- Midge tolerant wheat is an important tool
- Available as varietal blends
- We need to maintain that Sm-1 gene!
- What about predators?
- There is a parasitoid wasp that lays its eggs inside the larvae of the midge. Gross, and SO COOL
- Check out Pests & Predators and the @FieldHeroes We love our friends in the field!
- We get about 30% of the overwintering generation of wheat midge killed and controlled by that loss. So like that was saves people like $230 million a year in spring by keeping the numbers down, Tyler says
- Shelly Barkley of Alberta Agriculture deserves a huge shout out for all the work she does on surveys and scouting
- Let’s talk wheat stem sawfly
- Adult sawfly lays eggs in the stem of a wheat plant
- Once hatched, larvae eat the pith and move down the stem, robbing yield and causing lodging issues
- Lodging can be severe
- The adult looks like a wasp, black and yellow
- Forecasts are also made from fall scouting, by finding larvae in the stems
- You can gauge yield loss post-harvest, and relative risk: adults will emerge from stubble and attack adjacent fields
- More of a southern Alberta pest…maybe
- Sawfly also has a keen enemy, Bracon sephi
- The parasitoid lays its eggs inside the larvae
- Bracon sephi overwinters slightly higher up the stem
- Solid or semi-solid stem varieties are a physical resistance measure to the sawfly
- New term alert: augmented biological
- What about the T word? Tillage
- Can be useful in control of sawfly
- Check out the management graphic by Brian Beres! So good
- Bottom line: scout and then scout some more