Early season, The Bean Report

The Bean Report – April 24, 2024

APRIL 24, 2024

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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.

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 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 (2021-23), seedling survival has been 67% on average and there have been no yield differences among seeding rates tested.

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.

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%).

Yield Response (percentage of 2011-20 average) of peas sown on large fields (>120 acres) of various previous crops (stubble) in rotation. Data: MASC 2011-2020

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 2024 Guide to Crop Protection’s Re-cropping Restrictions Table for more information →

Time Between Pea Crops

If growing peas in 2024, think back to the last time you grew them. Although soil moisture conditions are drier entering this season, it is the moisture conditions and root rot development from your last pea crop that impacts your rotation length. 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 ten years. If conditions were wet when you last grew them, consider further extending the rotation between pea/susceptible crops with non-host crops.

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 confirms 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 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. 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.

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, 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.

Growing 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
  • Resources:

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

Soybean Seeding Dates