August 5, 2020

Crop Update
Scouting Update
Desiccating Field Peas
Soybean Stem Diseases
2020 Pulse Maximum Residue Limits (MRL) Advisory
Pre-Harvest Glyphosate Staging Guides for Faba Beans and Lentils

Listen to The Bean Report:

Crop Update

Soybeans range from early pod (R3) to early seed development (R5). Most soybeans in the province are at or near full pod (R4).
Dry beans range from early pod (R2) to 50% seed (R6). Most dry beans are at R3/R4 with advanced pod development.
Peas are mainly at early to mid-maturity (R5/R6) this week, and range anywhere from late pod-fill (late R4) to full maturity (R7).
Faba beans are mainly at R5 with full seeds within pods.
Lentils are now at the full pod (R6) stage.

Soybeans at R5 near Dauphin on July 31, 2020.

Soybeans at R5 to R6 near Lac du Bonnet on August 4.

Young seeds developing within a soybean pod at the 4th node from the top (R5 stage) on July 28 near Petersfield.

Young pods developing at the 4th node from the top (R3 stage) on July 28 near Balmoral.

Soybean pod development at the 4th node from the top (R4.5) with three pods developing at one node near Petersfield on July 28.

Dry bean pod development at Melita on July 23.

Dry beans at R5/R6 near Dauphin on July 31, 2020.

Herbicide-tolerant soybean variety evaluation trial at Arborg on July 28.

Pea variety trial at Melita at R4 on July 23.

Field peas at R6 near Gladstone on July 29.

Field peas at R6 near Teulon on July 28.

Faba beans at full pod (R5) near Roblin on July 31, 2020.

Faba beans at R5/full pod on July 28 near Warren.

Full faba bean pod at R5 on July 29 near Warren.

Scouting Notes

Grasshoppers are moving into soybeans, causing damage at field edges.
Pea aphids are still hanging around but shouldn’t pose much of a threat to peas and faba beans at this point in the season.
Thistle caterpillar is still present, but not considered a crop pest despite its ugly appearance in soybean fields.
Bacterial blight symptoms in pulse and soybean crops are advancing on leaves, pods and stems. New symptoms are also setting in from recent environmental damage.
It’s not hard to find Mycosphaerella/Ascochyta symptoms in peas and faba beans, but the advanced staging of these crops should make them resilient against yield loss.
Mid-season Phytophthora root rot is present in some soybean fields, along with early symptoms of northern stem canker. Be on the lookout for these and other stem diseases in soybeans.
Crops look great overall, thanks to adequate moisture across the province. However, there are still some pockets in MB where plants are stressed from the lack of moisture.

Soybean stem bruising and lodging following a hail storm near Plumas on July 27.

Soybean plant infected by Phytophthora root rot, showing a chocolate-brown stem lesion extending upward from the soil line, wilted leaves attached t the plant and poor root growth with no nodules (July 24 near Morris).

Septoria brown spot lesions on soybean leaves in the mid- to lower-canopy

Severe IDC symptoms persisting in a small pocket of the field at Arborg on July 28.

Mycosphaerella blight lesions on pea leaves at R6 near Roblin on July 31.

Bacterial blight in peas shows up as angular, water-soaked lesions. — Severe bacterial blight on peas.

Bacterial blight lesions on dry bean leaves near Morden on July 29.

Common blight lesions on dry beans at Morden on July 29.

Ascochyta/Mycosphaerella blight lesion and freckling on the lower leaves of a faba bean plant on July 23.

Advanced, sunken bacterial blight lesions on pea pods at the R4 stage on July 30 near Notre Dame de Lourdes.

Lady beetle larva among a pea aphid population in faba beans.

Pea aphids clustered on a faba bean leaf on July 28.

Desiccation Timing in Field Peas

Desiccation is the application of a contact herbicide or true desiccant that will dry down plant material and advance harvest (Table 1). This article covers are a few questions to run through as you consider whether late-season herbicide is truly needed.

The optimal timing for field pea desiccation is when seed moisture is less than 30% in the least mature part of the field. Applying earlier will result in higher residue concentrations in the seed, can cause yield and quality loss and can lock in the green colour of yellow peas prior to colour change. Applying later, we need to consider each product’s pre-harvest interval (PHI).

Walk the field to inspect plants from different areas. Inspect pods for colour change, shake the plant for rattling seeds, shell pods and squeeze seeds from the upper portion of the plant to assess firmness and seed colour. And do that drive-by assessment or stand on your vehicle to get a picture of percent maturity across the field.

Yellow peas are ready for desiccation at R7 when:

80% of the plant has turned yellow to brown in colour in 75–80% of the field.
Bottom pods are ripe and dry with seeds detached from the pod. Seeds rattle in the lowest pods.
Middle pods are wrinkled and seeds within have changed colour.
Top pods are wrinkled with an ‘orange peel’-like texture and have began changing colour. Seeds within top pods should have some colour change and split evenly when squeezed rather than squish.

Pods from the top, middle and bottom of the plant (L to R). The top pod has wrinkled and seeds in the top pod have some colour change and split when squeezed indicating that this field is just entering desiccation timing.

Pods from the top, middle and bottom of the plant (L to R). Seeds in the top pod squish when squeezed, indicating it is too early to desiccate in this field.

Split peas from the upper pods showing a range in yellow colour change.

Glyphosate is not registered as a desiccant in pulse crops but can be used for pre-harvest weed control. Like desiccants, it should only be applied pre-harvest when field pea seed moisture content is less than 30% to avoid residue levels greater than the maximum allowable limit.Farmers are advised to consult with their grain buyer before using this product on pulse crops. Some grain buyers may not accept pulse crops treated with pre-harvest glyphosate due to scrutiny in the global marketplace and low MRLs for some pulse crops in certain major markets. Glyphosate should not be used if peas are grown for seed due to the risk of reduced seed viability. For more information about pre-harvest glyphosate use, visit keepitclean.ca/glyphosate.

Soybean Stem Diseases

It’s important to identify stem diseases that may be present in your soybeans, as these pathogens can have a greater impact on production and quality than foliar diseases. These diseases include:

White mould
Phytophthora root and stem rot
Northern stem canker
Pod/stem blight
Anthracnose
Sudden death syndrome

The timeline for scouting is during the mid- to late-reproductive stages. Investigate the lower crop canopy in random areas of the field. Note that infected plants may or may not have upper-canopy symptoms.

Also be on the lookout for brown stem rot and charcoal rot, although they have not yet been confirmed in MB. If you suspect the presence of these diseases, contact us or submit a sample to a lab for confirmation.

On-Farm Network Update

August already! Hard to believe we’ll need our weigh wagons soon. Disease ratings in fungicide trials continue. With more moisture this season compared to the last couple of years, we are noticing increased disease pressure in some areas. It will be interesting to see how that influences yield results for pea, dry bean, soybean and faba bean fungicide trials.

This season we are working with Assiniboine Community College to assess canopy closure in our row spacing trials. So far, canopy closure measurements were taken at R1 and R3, with the third and final measurement slated for R5. At that R5 stage, they’ll also gather information on differences in late season weed pressure between spacings. We have trials comparing 15” vs 30” rows and 10” vs 20” rows this season.

As the season continues and you make observations on your own farms, questions and ideas may come up that could be great trial opportunities for the future. Whether it’s something you would like to test on your own farm next season, or simply a new trial type that would produce results useful to you, reach out! Get in touch with Megan at 204-751-0439 or megan@manitobapulse.ca

2020 Pulse Maximum Residue Limits (MRL) Advisory

Pre-Harvest Glyphosate Staging Guides for Faba Beans and Lentils

Bean App: Soybean Yield Estimator

Estimate your soybean yield prior to harvest to aid storage capacity and budgeting decisions. But remember, it’s only an estimate! Soybean yields are highly variable within fields. Increasing the number of samples and sampling from different areas of the field can improve the accuracy of this estimate.