Early season, The Bean Report

The Bean Report – May 4, 2022

May 4, 2022

  • Seeding Dates
  • Seed Treatments and Cool, Wet Soils
  • Residue Management Ahead of Soybeans
  • Get in the Field with the On-Farm Network
  • Save the Dates for Combine College: July 26 at Dauphin, July 28 at Portage la Prairie

Listen to The Bean Report:


It will be a while before we are able to start seeding in full force as some areas of the province are flooded or under a flood watch and others still have lingering snow drift from the recent storms. Hopefully the forecasted temperatures will help warm and dry soils across the province.

A field along highway 13 on May 2, 2022.


The latest weather conditions and reports from Manitoba Agriculture’s weather program, including these accumulated precipitation maps, may be accessed here. Check out the AgriMaps: Current Weather Conditions to view current reports from individual weather stations. These stations report air temperature, relative humidity, precipitation (hourly and since midnight), wind speed and direction, barometric pressure, and soil temperature and moisture at 5, 20, 50 and 100 cm depths.

Seeding Dates

Seed peas and faba beans early. Both crops tolerate cold temperatures well, so if you can, start seeding when soils warm up to 5°C at seeding depth. According to long-term crop insurance data, pea yields decline to about 80% relative yield if seeding in the third week of May. If pea seeding is delayed until June, yield potential drops below 65%. Later seeding often means the crop will flower during the heat of summer, which can result in loss of flowers and negatively impact yield.

For soybeans, it is comforting to know that seeding dates can be quite flexible throughout May in Manitoba. Start seeding when soil temperatures warm above 8°C as colder soils will delay emergence and increase the risk of chilling injury. According to research conducted by the soybean and pulse agronomy lab, seeding in the first three weeks of May has been shown to maximize soybean yield. Delaying seeding until June has reduced yield by 15% on average. If seeding soybeans later than usual, double check the variety’s days to maturity and that they will mature before your average fall frost date.

2010 - 2019: Seeding Date vs. Average Yield Response
Average relative yield by each seeding week from 2010 to 2019. Source: MASC

Average seeding dates for soybean and pulse crops according to MASC data (2010-2019).

Seed Treatments and Cool, Wet Soils

MPSG’s On-Farm Network has hosted 43 trials in soybeans comparing seed treatments to bare seed from 2015 to 2019. Seed treatments in these trials were applied on an insurance bases, meaning the pest risk level in each field was not known ahead of time. There was a significant, positive yield response to seed treatment 19% of the time, increasing yield by 2.6 bu/ac, on average at these responsive sites. One trial had a significant, negative yield response of -1.6 bu/ac. Roughly 80% of the time, there has not been a significant yield benefit to using a seed treatment in soybeans.

When is a seed treatment most likely to pay?

If seeding into wet soils or into soils with a known history of root rots and seedling diseases, fungicide seed treatments will offer some protection against Fusarium, Rhizoctonia, Pythium root rots. Note that seed treatment will only provide protection for two to three weeks after seeding (not emergence). These diseases can occur later in the season if conditions are conducive for infection, so seed treatment isn’t a complete solution. Seed treatments may also provide early-season protection from Aphanomyces in peas and Phytophthora root rot in soybeans. Soybeans and peas are most susceptible to Fusarium, Rhizoctonia and Pythium diseases during the early V-stages, while Phytophthora and Aphanomyces root rots may infect at any growth stage.

There is a root rot for every temperature. Pythium root rots prefer cool soils while Rhizoctonia, Fusarium and Phytophthora root rots prefer warm soils. It is difficult to distinguish root diseases from one another. Shared symptoms include poor emergence and root development, yellowing, discoloured roots and lesions on the root or stem tissue near the soil line.

Seed treatments with an insecticide component offer control or suppression of wireworms, seedcorn maggots, cutworms and pea leaf weevils, depending on the active ingredient. If your fields do not have a known history of these insects, consider a fungicide-only seed treatment.

View seed treatment options for soybean and pulse crops in the full Bean Report.

Seed Treatment Options for Soybeans and Pulse Crops

Below, find the seed treatment product tables from the 2022 Guide to Field Crop Protection for soybeans, dry beans, peas, lentils, chickpeas and faba beans.


Residue Management Ahead of Soybeans

Residue management practices ahead of seeding soybeans were investigated at Brandon, Carberry, Portage and Roblin from 2015 to 2017. Six treatments were compared: 1) tilled wheat residue and five no-till treatments where: 2) wheat residue was chopped and returned, 3) wheat residue was removed, 4) oat straw was chopped and returned, 5) oat straw was removed and 6) canola straw was chopped and returned.

Tillage warmed soils compared to no-till treatments by 1° to 5°C, on average (at 7 of 12 site-years). Half of the time, tillage reduced soil moisture and the other half of the time, there was no effect on soil moisture. Removing straw increased soil temperatures by 1° to 3°C (at 7 of 12 site-years) and reduced soil moisture (at 5 of 12 site-years) compared to treatments where straw was chopped and returned to the field.

Days to soybean emergence were similar in all treatments and there was no effect on plant stand. Soybean yield was unaffected by residue management treatments at 10 of the 12 site-years. Read the full summary of this research in the Science Edition.

Get in the Field with the On-Farm Network

With the arrival of our summer students next week, the On-Farm Network (OFN) team is nearly ready to hit the ground running into the 2022 field season!

Check out the trial lineup this year, which features 51 confirmed trials. This number is subject to change throughout the season as trials are added, so if you’re interested in adding a soybean, field pea, dry bean or faba bean field to the lineup, we’re here for you. Chat with Leanne Koroscil at leanne@manitobapulse.ca or 204-751-0439 to evaluate your production questions through an on-farm trial this season.

Be sure to keep an eye out for OFN updates in The Bean ReportPulse Beat, and of course the OFN Twitter account (@OFNagronomist).

Manitoba Agriculture’s CropTalk Webinars run weekly on Wednesday mornings (9:00 to 10:00 a.m.). Register here!