APRIL 26, 2023

• Seeding Peas: Tips to Establishing a Strong Crop
  • Seeding Date
  • Seeding Rates, Target Plant Populations and Row Spacing
  • Seeding Depth
  • Residue Management and Preceding Crop
  • Time Between Pea Crops
  • Seed Treatments
  • Fertility and Inoculation
  • Rolling
  • Early-Season Weed Control
• Seeding Faba Beans
• Choosing a Soybean Seeding Date

Seeding Peas: Establish a Strong Crop

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.

MASC seeding deadline for field peas is June 15, with an extended seeding period of June 15 to 20.

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.

Target 7 – 8 live 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%. In On-Farm Network pea seeding rate trials in 2021 and 2022, seedling survival has been, on average, 68% (range: 46 to 100%).

Peas are typically seeded on narrow-rows of 6 to 12 inches to allow plants to knit tendrils across rows and improve standability.

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.

Residue Management and Preceding Crop

Cooler soil caused by surface residue in no-till systems will not be detrimental, but the mulch may trap excess moisture. Research is currently underway evaluating preceding crop, tillage system and P fertilizer at Roblin and Carman through the Agronomist-in-Residence’s applied soybean and pulse agronomy lab. Results are expected soon!

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. Chemistries of most concern are those that contain clopyralid or ethametsulfuron (Muster). Several others may be of concern following dry growing seasons due to limited microbial breakdown. Refer to the 2023 Guide to Crop Protection’s Re-cropping Restrictions Table for more information →

Time Between Pea Crops

If Aphanomyces is not present in a field, peas may be grown once every four years to minimize Mycosphaerella blight disease pressure. If Aphanomyces has been confirmed in a field, peas should only be grown once every six to eight years. Consider the environment the last time peas were grown – if it was wet, take a longer break between crops.

Developed by Dr. Steve Shirtliffe and his team at the University of Saskatchewan, there is a new Aphanomyces Risk Evaluation App (AREA) tool. 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. Once a field is selected, answer the pop-up question indicating if peas or another crop were grown in that field in 2022. From there, the risk of Aphanomyces in that field 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 and the soil texture.

Risk is greatest in fields where May to June precipitation was high the last time peas were grown.

• Explore the AREA tool here →
• Reducing Root Rot Risk →
• Aphanomyces Root Rot Summary Video (25 minutes) →

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).

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 and Rancona Trio), 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.

New in 2023, MPSG is 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.

• On-Farm Network Seed Treatment Trial Protocol →
• Seed Treatment Options for Field Peas →

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.

Seeding Faba Beans

• Seeding Date: as early as the field is passable, during mid-April to early May
• Target Plant Populations: target 180,000 live plants/ac (45 plants/m²). Seed size can vary widely, from 300 to 750 g/1000 seeds
• Seeding Depth: 2 to 3 inches, ensuring adequate seed to soil moisture contact
• Row Spacing: 6 to 12 inch rows
• Inoculant: inoculate with Rhizobium leguminosarum bacteria
• Seed Treatments: consider a fungicide seed treatment if seeding into saturated soils. consider an insecticide seed treatment if pea leaf weevil populations are great in your region, as faba beans are a preferred food source

Tips to Avoid Faba Bean Plugging Issues:

• Reduce planting speed to less than 5 mph
• Use extra-coarse metering rollers or augers with a large volume between flutes or flights
• Increase air flow through distribution system (i.e., set to maximum fan speed, install fan with high airflow capacity)
• Reduce number of tight turns in the field to prevent innermost openers from reversing in soil
• Eliminate sags in distribution hoses and avoid over-tightening hose clamps
• Deliver seed via fertilizer tubes, if larger cross-sectional area than seed delivery tubes
• Remove inline blockage sensors that may obstruct flow
• Meter seed out of two tanks instead of one for desired seeding rate and reduced flow-rate from individual meter
• Sieve out largest seeds prior to seeding. Faba bean can vary widely in seed size
• Reduce seeding rate if germination and expected seed survival are high
• Consider seeding the field twice over at half the application rate
• Reduce outside diameter of metering rollers, which increases clearance with metering housing and reduces the probability of seeds jamming between the roller and housing
• Use vertical tower-style distribution manifolds. Some are more prone to plugging than others

Source: Prairie Agricultural Machinery Institute

Choosing a Soybean Seeding Date

Calendar date – Aim to plant during the second to third weeks in May for high yield potential and reduced frost risk. A rule of thumb for early planting is to seed within two weeks of your region’s last spring frost date to ensure seedlings are not injured by frost after emergence. Emerged seedlings can tolerate air temperatures of -2.2°C for a brief period if plants have had a chance to harden, but cannot recover if the main growing point is killed. If the growing point is only injured slightly, growth may resume from the axillary buds. Avoid planting in June due to lower yield potential.

• Average Date of the Last Spring Frost →
• Refining Soybean Seeding Window Recommendations →
• Soybean Yield Response to Seeding Week (MASC 2007-2021) →

Soil temperature –In recent controlled environment experiments conducted by Dr. Mohr at AAFC-Brandon, soybeans germinated 11-15 days later, on average, under temperatures of 5°C vs. 10°C. At temperatures of 15°C, soybeans germinated 3-4 days earlier than at 10°C. In terms of emergence, previous research has shown that soybeans will emerge within 3-4 weeks when seeded into 6–12°C soils and 4–16 days when seeded into 14–22°C soils (based on soil temperatures at a 5 cm depth at 10:00 a.m. for two consecutive days). Warm soil temperatures will result in faster emergence. Residue management will have a minor impact on plant population and yield if soybeans are seeded during optimal calendar dates and into warm soil.

24-hour forecast – Seeds imbibe water within the first 24 hours after seeding. If cold and wet conditions are expected during this period, wait to plant to avoid chilling injury. Extended periods of poor weather after seeding can also delay emergence and reduce seedling vigour.

Personal risk profile – Adjust planting dates according to your individual frost risk, based on where you are located in the province, and the amount of soybean acres you are planting compared to other crops that may need to be seeded earlier. Ensure more frost-tolerant crops are seeded before soybeans. If you want to experiment with earlier planting, try a few acres first and spread out your planting dates.