Table of contents

Bacterial Blight

Pseudomonas pisi (P. syringae pupisi)

What to look for?
Often seen in wet seasons in lodged crops. Pods and leaves have a greasy appearance.


Photo: Howard
Picture description
Bacterial blight in peas.

Photo: Zimmer
Picture description
Bacterial blight - translucent water soaked foliage.


Photo: Evans

Picture description
"Greasy" severely damaged pods and leaves.


Photo: Platford

Picture description
Blight damaged pods.

Downy Mildew

Peronospora viciae

What to look for?
The disease is seed-borne and is able to persist in the soil for a number of years.


Photo: Evans
Picture description
Distorted virus-like infection of pea shoots.

Photo: Evans
Picture description
Small leaflets and grayish colour on leaflet stems.


Photo: Morrall

Picture description
Distinct downy gray mildew on leaflet undersides.

Management strategy
Disease levels of up to 15% have been observed in Alberta. Seed treatment, crop rotation and good clean seed are control measures.

Ascochyta Leaf and Pod Spot

Ascochyta pisi

What to look for?
Not a very common disease. Disease is similar to the more common Mycosphaerella blight and Ascochyta foot rot.


Photo: Seaman
Picture description
Ascochyta shoot infection.

Photo: Evans
Picture description
Seedling infection.


Photo: Evans

Picture description
Ascochyta pod infection.
   


Management strategy
Many field pea cultivars are resistant to A. pisi. Crop rotation of 3 - 4 years along with foliar fungicide treatments will give control of this and many other diseases.

Ascochyta Seedborne

Ascochyta pisi

What to look for?


Photo: Evans
Picture description
Peas discoloured by Ascochyta pisi.

Mycosphaerella Blight and Foot Rot

Mycosphaerella pinodes and Phoma medicaginis

What to look for?
Severe infection under cold wet weather can reduce yields by up to 50% from these fungi.


Photo: Zimmer
Picture description
Both these diseases can attack stems, leaves and pods.

Photo: Zimmer
Picture description
Severe infection by one or both of these fungi.

Photo: Zimmer
Picture description
Purple spots of M. pinodes.

Photo: Zimmer
Picture description
M. pinodes and ascochyta foot rot on pea vine and stipules. Both fungi are seed- and stubble-borne.

Photo: Zimmer
Picture description
M. pinodes on pods.
   

Management strategy
Crop rotation of 3 - 4 years, disease-free seed, cultivate under crop residue and timely foliar fungicide application is wet rainy seasons.

Powdery Mildew

Erysiphe polygoni

What to look for?
Powdery mildew spreads very rapidly late in the season especially under humid by rain-free conditions.


Photo: Platford
Picture description
Severe powdery mildew on leaves, pods and vines.

Photo: Zimmer
Picture description
Severe powdery mildew.


Management strategy
The fungus overwinters as cleistothecia on crop residue ascospores are released in the spring. Late planted pea crops are very prone to severe damage.

Seedling Blight

Pythium sp.

What to look for?
Pythium, Fusarium and Aphanomyces seedling blight can take out young pea seedlings especially on heavy soil prone to waterlogging.


Photo: Howard
Picture description
Pythium damaged seedlings.

Photo: Morrall
Picture description
Seed emergence failure on wet heavy soil.

Management strategy
Seed treatments along with an avoidance of soils prone to flooding and 4 - 5 year rotation on problem fields.

Damping Off and Root Rot

Pythium sp.

What to look for?
As with seedling blight but in some instances the seedling literally sit in the soil with little or no growth.


Photo: Howard
Picture description
Healthy seedling and blighted seedling.
   

Management strategy
Glyphosate applied to a maturing pea crop may show in the seed and result in death or distortion of a percentage of the seedlings.

Pythium Tip Blight

Pythium sp.

What to look for?
A peculiar disease whereby Pythium species take out shoots some 3 - 4 inches off the ground on succulent shoot of vigorously growing pea seedlings. Twisted tops that bend or break off appear to be wind whipped.


Photo: Kaminski/Evans
Picture description
Aerial pythium infection.
   

Stem and Root Rot

Sclerotinia sclerotiorum

What to look for?
Sclerotinia was formerly a serious problem when the old full heavy pea crops lodged. In the new dwarf leafless types this disease is much less of a problem. As much as 80% yield losses occurred with pre-1970 pea crops from this disease.


Photo: Morrall
Picture description
White stem rot appears.

Photo: Morrall
Picture description
Sclerotia inside pea pod.

Management strategy
Do not grow peas after crops susceptible to sclerotinia such as canola and beans. Follow a 3 - 4 year rotation and grow leafless types.

Pea Seedborne Mosaic Virus

Pea Seedborne Mosaic Virus

What to look for?
Pea seed-borne mosaic virus has been removed through the certification system including symptomless types. Very few plant viruses are seed-borne.


Photo: Zimmer
Picture description
Symptomless pea virus infection.

Photo: Zimmer
Picture description
Virus infected and virus-free seed.

Bean Yellow Mosaic Virus

What to look for?
This disease is not seed-borne and is of rare occurrence on the prairies.


Photo: Evans
Picture description
Bean yellow mosaic infection.

Photo: Evans
Picture description
Typical bean yellow mosaic symptoms.

Alternaria Leaf Spot

Alternaria alternata

What to look for?
An unusual disease of peas occasionally seen in some pea fields.


Photo: Howard
Picture description
Target-like spots of the alternaria infection.

Septoria Leaf Blotch

Septoria pisi

What to look for?
This disease usually only attacks older leaves though some cultivars of peas are much more susceptible than others.


Photo: Zimmer
Picture description
Blotch symptoms.

Photo: Evans
Picture description
Septoria on a young pea leaf.

Photo: Evans
Picture description
Dark brown pinpoint pycnidia present. Typical blotch symptoms.


Management strategy
Not usually a problem in most pea cultivars

Fusarium Wilt

Fusarium oxysporum f.sp. pisi

What to look for?
The lower leaves of the affected plant turn yellow and there is a stunting or dwarfing of the plant. The affected stem, just below the soil line, turns reddish to dark brown. The internal woody stem tissue might also turn a brick red.


Photo: Sweeney
Picture description
Patch of wilted peas.

Photo: Pepin
Picture description
Fusarium wilt in a pea field.

Management strategy
This pea disease occurs in many races and has the potential to be the most destructive disease on the prairies. Resistance to Fusarium wilt exist even to the extant of individual pea cultivars being resistant to individual races of this fungus. To date this disease has not been a problem in Alberta but this fungus has a huge destructive potential.

Aster Yellows

Mycoplasma (Phytoplasma)

What to look for?
Aster Yellows infections are rare in the pea crop in Alberta.


Photo: Unknown
Picture description
Intense fasciation and distortion.
   

Go to Diseases of Vegetables - Pea for more information on diseases of peas.

Controlling Field Pea Diseases in Direct Seeding Systems

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