Fungicide Decision Tool for Managing Mycosphaerella Blight in Field Peas

Jul 02, 2025

When your peas have reached V10 (10th node stage), it is an ideal time to start scouting each field to evaluate if a fungicide application to manage Mycosphaerella blight is warranted. Continue scouting for symptoms from V10 (10th true node) to R2 (beginning bloom), during mid-June to late July.

Mycosphaerella (Ascochyta) blight is the most widespread and economically damaging foliar disease of Manitoba field peas. Peas are the single host crop of Mycosphaerella but it can be managed by foliar fungicide.

This pathogen can be stubble-, air-, soil- and seed-borne. Spores can travel long distances by air, meaning there is a disease risk even in fields where peas have not been grown previously.

The impact of disease severity on yield will depend on how early the disease sets in and how quickly it progresses into the upper crop canopy. Early infections during the bloom to early/mid-pod stages cause the most damage if left untreated.

Use this fungicide decision worksheet when scouting to determine if fungicide application is necessary.

It is a great idea to down load the

Fungicide Decision Worksheet for Managing Mycosphaerella Blight in Field Peas – Manitoba Pulse & Soybean Growers

Pro tip: If you will be scouting several pea fields, from the download, screen shot a picture of the handy rating scale to your mobile device several times.

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