Seeding Date
Seed peas as early as possible from late April to early May for maximum yield potential. Peas are more tolerant to spring frosts than other crops because pea cotyledons remain underground. If frost injury occurs, new shoots will emerge from axillary buds that are protected under the soil surface. The minimum soil temperatures for germination to occur in peas is 4°C, but emergence will be quicker and more even if soils are consistently at or above 5°C.
Early planting also means peas flower and pod earlier in the summer, avoiding heat blasting of flower buds and peak pea aphid populations. Fusarium and Aphanomyces root rots both prefer warm, saturated soils. Planting into soil temperatures below 10°C within one week of seeding reduced root rot severity by 17-26% and improved yield by 4-8 bu/ac compared to warmer soil temperatures in North Dakota research.
2024 research in North Dakota, looked at seeding dates and yields using newer pea varieties. In previous NDSU studies, it was noted that much of the yield loss was due to varieties not having resistance to the disease downy mildew. With new genetics for downy mildew offered in most of the new pea varieties, yield trends the past several years have been increased at the later seeding dates. Dry Pea Response to Seeding Date and Variety, 2024 NDSU Langdon Research Extension Center
This one-year study would seem to indicate that the planting window for field peas may be extended for
northeastern North Dakota as they found there were no significant or small differences between the traits observed when averaged over seeding dates (in 2024, starting May 13 and as late as June 7) or averaged over varieties (Chrome and Spider). Additional studies are needed to verify this information.
For 2025, MASC seeding deadline for field peas is June 15, with an extended seeding period of June 16 to 20. Manitoba Seeding Deadlines (2025)
Seeding Rates, Target Plant Populations
Start by using high quality, disease-free seed. Maintain seed quality through gentle seed handling. Use a conveyor belt if possible or if using an auger, run it slow and full to reduce cracks.
Seed moisture is an important factor to consider to maximize the amount of seeds that become viable healthy plants. An MPSG-funded study was conducted with PAMI to determine the impact of fan speed and moisture content on pea seed quality through an air seeder. Surprisingly, seed moisture content had the biggest impact on germination, vigour and seed coat damage over air fan speed. If your seed moisture content is on the lower side focus on gentle handling and consider reducing your estimated seedling survival to account for higher mortality through handling and your seeder.
Target 7 – 8 live pea plants/ft2 (320,000-360,000 plants/ac, 80-90 live plants/m2). Adjust the seeding rate (lbs/ac) to account for expected seedling survival and seed weight, which varies considerably among varieties and seed lots. Thousand seed weight typically ranges from 125-300 grams/1000 seeds. A typical seedling survival for peas is ballparked around 85%. However, in MPSG’s On-Farm Network pea seeding rate trials (2021-24), seedling survival has been 72% on average and there have been no yield differences among seeding rates tested. It is important to note that dropping seeding rates too low can negatively impact crop competition with weeds and standability. Peas are typically seeded on narrow-rows of 6 to 12 inches to allow plants to knit tendrils across rows and improve standability.
Conduct a soak test to assess seed damage:
Place 200 seeds in water and calculate the percentage of seeds that swell. Seeds that lose their seed coat will not produce a viable plant.
Need help determining your Pea Seeding Rate in as quick as a few clicks?
There is an MASC Manitoba online calculator that can help. Enter you specific information in the white boxes and seeding rate and cost calculations appear in the grey boxes.
Seeding Depth
Seed peas at 1.5 to 2 inches deep, ensuring they are planted into moisture. Since pea cotyledons remain below ground, they can emerge from a deeper depth than soybeans. Check seed depth as soil conditions change and also check depth across the width of the seeder to ensure that no areas are seeding too deep or too shallow.
Rotational Considerations
Peas are commonly grown following wheat, cereals or canola. According to MASC data (2011-2020), relative yield response of peas is greatest following red spring wheat (101%), canola (104%) or soybeans (106%).
Check herbicide history before growing peas. Some herbicide residues do not degrade quickly, and can persist
in the soil for months or years following application, which restricts the crops that can be grown in rotation. Watch out for ethametsulfuron (Muster) and products containing clopyralid (e.g., Cirpreme, Curtail M, Eclipse III, Esteem, Lontrel 360, MPOWER Battlefront CM, Clobber G/M or Foxxy CM, Prestige XC/XL, Pyralid, Spectrum) in rotations containing peas, soybeans and dry beans. Clopyralid requires >175 mm of precipitation in the year of application and adequate temperatures (20°C) for successful microbial breakdown.
To ensure your crops are not at risk of damage from previously-applied chemicals, refer to the re-cropping restrictions table in the Refer to the Manitoba 2025 Guide to Crop Protection’s Re-cropping Restrictions Table for more information
- Peas are particularly sensitive to some chemistries (often those that require more moisture to break down) and residual herbicide injury can be displayed as
- – Prolific branching from base of plant (loss of apical dominance)
- – Internode compression
- – New growth pale (not always)
- – Leaf cupping or necrosis around leaf veins, drawstringing
- May see symptoms pop up ~2 weeks after a rain, as herbicide moves into the pea root zone
Time Between Pea Crops
If growing peas in 2025, think back to the last time you grew them.
It is the moisture conditions and root rot development that occurred in the year of your last pea crop that determines how long your rotation length should be. If Aphanomyces is not present in a field, peas may be grown once every four years. If Aphanomyces has been confirmed in a field, peas should only be grown once every six to ten years. If conditions were wet when you last grew them, consider further extending the rotation between pea/susceptible crops with non-host crops. Risk is greatest in fields where May to June precipitation was high the last time peas were grown.
If you had root rot in your last pea crop but did not confirm the pathogen through a test, consider soil sampling this spring. Aphanomyces has big implications on rotation length and often occurs with a complex of multiple pathogens. Testing needs to be done to confirm if the root rot was Aphanomyces and helps you better determine management strategies and your rotation length. Due to the nature of Aphanomyces and its thick-walled oospores a DNA test is needed for confirmation. For a list of labs and more information on sampling and interpretation click here.
The gradient of Aphanomyces infection in peas where the most severe disease can be seen on the left versus healthy plants on the right. Aphanomyces infections are characterized by yellowing and wilting of shoots, pinching of epicotyl, stopping abruptly at the soil line, and lateral roots with watery and honey-brown decay. Source: Dr. Syama Chatterton, Agriculture and Agri-Food Canada (AAFC).
Unsure of the last time peas were grown on your field or how much growing season moisture occurred the last time peas were grown there?
There’s a desktop app for that!
The Aphanomyces Risk Evaluation App (AREA) is a tool developed by Dr. Steve Shirtliffe and his team at the University of Saskatchewan to help determine your Aphanomyces risk. In the app, navigate to your field and use the ‘point’ tool to select the field. Toggle layers and their transparency in the top right of the map to improve viewability. From there, the risk of Aphanomyces in that field would have been in 2024 will pop up on the right side. Risk is calculated based on the crop rotation history of that field, May to June precipitation of each year up to 2023 and the soil texture. Currently, data hasn’t been updated to give an risk of aphanomyces for 2025.
When you first look at the map, you will see certain fields highlighted in lime green colour. The app identified those fields from satellite imagery as growing peas in 2023. We found that for these highlighted fields, you need to use the rectangle tool, draw a rectangle in the field, then click the point button and click anywhere on the rectangle you just draw and then the field and risk information will pop up.
Stop the Rot – Root Rot Task Force
The Root Rot Task Force, consisting of contributors from Alberta Pulse Growers, Manitoba Pulse and Soybean Growers, and Saskatchewan Pulse Growers, created this online resource for anyone working with pulse crops to learn strategies for preventing, diagnosing, and treating root rot complex. Their webpage, Pulse Root Rot Network is full of excellent resources and encourages to “stop the rot”
Fertility and Inoculation
Inoculate peas with Rhizobium leguminosarum bacteria, even on fields with a history of peas. This will help facilitate root nodule development and nitrogen fixation. Single inoculation is often sufficient. Consider double inoculating fields with no history of peas or using a granular inoculant when seeding conditions are unfavourable (e.g., drought, excess moisture, acidic soil). Inoculant Options for Pulse Crops In addition to Rhizobium bacteria, some inoculants contain supplementary organisms and compounds that may claim to enhance the nitrogen-fixing process or provide other benefits to the crop (Table 4).
Fertilizer toxicity can occur when fertilizer concentration is too high too close to the seed. The maximum safe rate of seed-placed P for peas is 20 lbs actual P2O5 per acre, based on disk or knife openers with a 1″ spread on 6-7″ row spacing in good to excellent soil moisture.
Seed Treatments
If seeding into saturated soils, or soils with a known history of root rots and seedling diseases, consider a fungicide seed treatment to protect against Fusarium, Rhizoctonia and Pythium root rots. Seed treatments will provide protection for two to three weeks after seeding, helping plants get established in challenging conditions. Seed treatments are available for suppression of Aphanomyces (Intego Solo, Rancona Trio and Zeltera Pulse), however they will only provide early-season suppression of this disease.
Seed treatments with an insecticide component will offer control or suppression of wireworms, seedcorn maggots, cutworms and pea leaf weevils, depending on the product. If your fields do not have a known history of these insects and are at low risk, consider a fungicide-only seed treatment.
Starting last year, MPSG is now hosting pea seed treatment trials with interested farmers! Evaluate if a fungicide or insecticide seed treatment will provide a return on investment on your farm by participating in a trial.
Rolling
Land rolling can greatly improve harvestability and reduce earth tag on seed, even on soil without stones. Rolling can be done immediately after seeding or post-emergence at the 2nd to 3rd true node stages. Consider post-emergent rolling if soil crusting and sealing is likely to be an issue in your fields. If rolling post-emergence, roll during the warmest part of the day. Avoid rolling as the crop is just emerging or if the crop is stressed from herbicide or frost.
Early-Season Weed Control
Early season weed control is important for preventing yield loss, as peas are poor competitors against weeds. A pre-seed or pre-emergent herbicide application is recommended, along with a timely in-crop application, applied when weeds are small and actively growing.
Pre-emergent herbicides can offer control of Group 2-resistant broadleaf weeds, which have limited in-crop control options. Pea yield can be reduced by up to 25% if weed control is delayed until four weeks after emergence.
*Additional info: Gowan Canada has recently expanded the label, for its pre-plant granular herbicide Fortress MicroActiv, to include its use in field peas and lentils (fall). Fortress, which combines triallate (Group 15) with trifluralin (Group 3), is registered for control of wild oat and wild millet (green and yellow foxtail) plus suppression of certain other annual broadleaf weeds.