| | Healthy crop | Bacterial Blight | Downy Mildew | Leaf and Pod Spot | Seedborne | Mycosphaerella Blight and Ascochyta Foot Rot | Powdery Mildew | Seedling Blight | Damping Off and Root Rot | Pythium Tip Blight | Stem and Root Rot | Pea Seedborne Mosaic Virus | Bean Yellow Mosaic Virus | Alternaria Leaf Spot | Septoria Leaf Blotch | Fusarium Wilt | Phyllody-Aster Yellows
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Healthy Crop (cv. Maple)
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What to look for?
Pea growing on the Canadian prairies has only become feasible because of leafless cultivars that do not lodge and dwarf growing types of pea. Lodged peas in wet seasons used to rot entirely.
Photo: Evans | Picture description
A stand of Maple field peas. |
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Management strategy
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. |
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Photo: Evans | .
Picture description
"Greasy" severely damaged pods and leaves. | .
Photo: Platford | .
Picture description
Blight damaged pods. |
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Management strategy
Downy Mildew.
Peronospora viciae
What to look for?
This disease is particularly destructive in the UK and in past years on canning peas in southern Alberta. 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. |
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Photo: Morrall | .
Picture description
Distinct downy gray mildew on leaflet undersides. |
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Management strategy
Disease levels of up to 15% have been observed in Alberta. Seed treatment, crop rotation and good clean seed are control measures.
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. |
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Photo: Evans | .
Picture description
Ascochyta pod infection. |  | |
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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.
Seedborne.
Ascochyta pisi
What to look for?
Photo: Evans | Picture description
Peas discoloured by Ascochyta pisi. |
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Management strategy
Mycosphaerella Blight and Ascochyta 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. |
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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. |
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Photo: Zimmer | Picture description
M.pinodes on pods. | | |
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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. |
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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. |
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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. | | |
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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. | | |
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Management strategy
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 muchless 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. |
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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. |
.Management strategy
Bean Yellow Mosaic Virus.
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. |
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Management strategy
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. |
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Management strategy
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. |
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Photo: Evans | Picture description
Dark brown pinpoint pycnidia present. Typical blotch symptoms. |
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Management strategy
Not usually a problem in most pea cultivars
Fusarium Wilt.
Fusarium oxysporum f.sp. pisi
What to look for?
Often in back yard gardens in Edmonton peas may fail to grow often do to significant build-up of the wilt pathogen. If you are looking for pea diseases in Alberta do a check of old established vegetable gardens where peas may have been grown annually for 50 or more years.
Photo: Sweeney | Picture description
Patch of wilted peas. |
Photo: Pepin | Picture description
Fusarium wilt in a pea field. |
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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.
Phyllody-Aster Yellows.
Mycoplasma (Phytoplasma)
What to look for?
Phytoplasma infections are rare in the pea crop in Alberta.
Photo: Unknown | Picture description
Intense faciation and distortion. | | |
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Management strategy
Go to Diseases of Vegetables - Pea for more information on diseases of peas.
Photographs and information assembled and prepared for AAFRD by Dr. Ieaun R. Evans Agri-Trend Agrology Ltd. |
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