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Pea Disease Diagnostic Series ( PP1790)

This series aids in disease identification.

Samuel Markell, Extension Plant Pathologist, North Dakota State University

Julie Pasche, Dry Bean and Pulse Crop Pathologist, North Dakota State University; Lyndon Porter, Research Plant Pathologist – Legumes, U.S. Department of Agriculture-Agricultural Research Service, Prosser, Wash.


Roots and Wilts

Fusarium root rot

Fusarium avenaceum, F. solani f. sp. pisi and other species

Figure 1 Photo by Porter, USDA-ARS

FIGURE 1 – Discrete lesions expanding from the point of seed attachment and coalescing into larger lesions
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 2Photo by Porter-USDA-ARS

FIGURE 2 – Advanced lesions affecting large areas of roots and hypocotyls
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 3Photo by Porter - USDA-ARS

FIGURE 3 – Infected plants yellowing from the base upward
Photo: L. Porter, USDA-ARS Prosser, WA

AUTHORS: Julie S. Pasche, Lyndon Porter and Kimberly Zitnick-Anderson

SYMPTOMS

• Red to brown-black below-ground lesions
• Lateral root reduction and complete destruction in severe infections
• Below-ground red discolored vascular tissue is possible
• Above-ground stunting, yellowing and necrosis

FACTORS FAVORING DEVELOPMENT

• Temperatures from 73 to 83 F and wet soils
• Soil compaction and plant stress
• Contaminated seed or plant debris

IMPORTANT FACTS

• Alternative hosts include dry beans, soybean, chickpea and lentil
• Often seen in a complex with other root rots
• Above-ground symptoms often not seen until flowering
• Can be confused with other root rots and abiotic stress (water damage, etc.)

Aphanomyces root rot

Aphanomyces euteiches

Figure 1Photo Porter-USDA-ARS

FIGURE 1 – Caramel-brown infected roots (R) and healthy roots (L)
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 2Photo Porter-USDA-ARS

FIGURE 2 – Infected roots and yellowing lower leaves
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 3Photo Porter-USDA-ARS

FIGURE 3 – Outer root tissue sloughing off and exposing inner vascular tissue
Photo: L. Porter, USDA-ARS Prosser, WA

AUTHOR: Lyndon Porter

SYMPTOMS

• Caramel-brown root and below-ground stem
• Outer root and below-ground stem tissue will slough off, exposing the vascular tissue
• Lower leaves turn yellow; the plant may be stunted, wilt and/or die prematurely

FACTORS FAVORING DEVELOPMENT

• Cool and wet spring conditions
• Low-lying areas
• Short rotations with peas or lentils

IMPORTANT FACTS

• Thick-walled spores can survive in soil for 20 years or more
• Lentils are a host, but chickpeas and faba beans are not
• Crop rotations of six or more years with nonhost can help reduce disease
• Can be confused with other root rots and abiotic stress (water damage, etc.)

Pythium seed and seedling rot

Pythium ultimum and other Pythium species

Figure 1Photo Porter-USDA-ARS

FIGURE 1 – Light brown internal seed rot
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 2Photo Porter-USDA-ARS

FIGURE 2 – Rotted seed coated with soil
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 3Photo Porter-UDSA-ARS

FIGURE 3 – Emerged plants with reduced vigor
Photo: L. Porter, USDA-ARS Prosser, WA

Rhizoctonia seed, seedling and root rot

Rhizoctonia solani AG 2-1, 4, 5 and 8

Figure 1Photo Porter-USDA-ARS

FIGURE 1 – Sunken brown lesions on below-ground stem tissue
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 2Photo Porter-USDA-ARS

FIGURE 2 – Browning of the roots and pinching-off of root tips
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 3Photo Chang, Alberta Ag and Forestry

FIGURE 3 – Peas infected with Rhizoctonia
Photo: K. Chang, Alberta Agriculture and Forestry

AUTHORS: Timothy Paulitz, Dipak Sharma-Poudyal, Lyndon Porter, Weidong Chen and Lindsey du Toit

SYMPTOMS

• Seeds may rot in soil, resulting in poor emergence
• Seedlings have reddish-brown, sunken lesions on roots and base of stem
• Pinching-off of tips of the main tap root and secondary roots
• Plants become stunted and yellow

FACTORS FAVORING DEVELOPMENT

• Wet, cool soils
• Seed with poor germination

IMPORTANT FACTS

• Pathogen can survive in soil and plant debris
• Rotation is largely ineffective and resistant cultivars are not available
• Fungicide seed treatments are recommended
• Can be confused with other root rots, water damage

Fusarium wilt

Fusarium oxysporum f. sp. pisi

Figure 1Photo Markell - NDSU

FIGURE 1 – Yellowing and curling of leaves
Photo: S. Markell, NDSU

Figure 2Photo Guy - WA State U

FIGURE 2 – Curling and yellowing of lower leaves on one side of the plant only
Photo: S. Guy, Washington St. U.

Figure 3Photo Porter - USDA-ARS

FIGURE 3 – Orange-red vascular discoloration extending into the stem
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 4Photo Markell - NDSU

FIGURE 4 – Severe vascular discoloration
Photo: S. Markell, NDSU

AUTHOR: Stephen Guy

SYMPTOMS

• Leaves curl and yellow progressively from the base of the plant upward, sometimes more severe on one side of the plant
• Root vascular tissue is shades of yellow, orange or red, extending into the base of stem
• Field distribution is scattered plants or concentrated patches
• Plants may wilt

FACTORS FAVORING DEVELOPMENT

• Previous history of disease in the field
• Frequent cropping of susceptible varieties
• Late planting

IMPORTANT FACTS

• Can survive in soil for 10 years or more
• The fungus penetrates root tips and blocks vascular tissue
• Pathogen has more than one race and resistant varieties may not be effective against all races
• Can be confused with Aphanomyces and Fusarium root rots and abiotic stress

Spots and Lesions

Ascochyta blight

Ascochyta pisi, A. pinodes,
Phoma medicaginis var. pinodella

Figure 1Photo Wunsch - NDSU

FIGURE 1 – Oval lesions with concentric rings
Photo: M. Wunsch, NDSU

Figure 2Photo Wunsch-NDSU

FIGURE 2 – Irregular flecks on leaf, extending to petioles and stems
Photo: M. Wunsch, NDSU

Figure 3Photo - Wunsch - NDSU

FIGURE 3 – Small, irregular pod lesions
Photo: M. Wunsch, NDSU

Figure 4Photo Wunsch - NDSU

FIGURE 4 – Stem lesions
Photo: M. Wunsch, NDSU

AUTHOR:Michael Wunsch

SYMPTOMS

• Leaf lesions are dark, irregular flecks and/or circular to oval lesions, with a concentric ring pattern
• Purplish stem lesions develop at nodes, elongate and may girdle stem
• Pod lesions are small, irregular to circular and brown to purplish black
• Seed may be discolored

FACTORS FAVORING DEVELOPMENT

• Cool, wet weather
• Short rotational intervals between pea crops

IMPORTANT FACTS

• Primarily residue-borne but can be seedborne
• Crop rotation reduces but does not eliminate pathogen inoculum
• The host range of the causal pathogens is limited to field peas
• Can be confused with bacterial blight or Septoria blight

Bacterial blight and brown spot

Pseudomonas syringae pv. pisi and P. syringae pv. syringa

Figure 1Photo Harveson - U of NE

FIGURE 1 – Angular leaf lesions delimited by veins
Photo: R. Harveson, Univ. of Nebraska

Figure 2Photo Harveson - U of NE

FIGURE 2 – Watery stem lesions forming in linear patterns as disease progresses
Photo: R. Harveson, Univ. of Nebraska

Figure 3Photo Harveson - U of NE

FIGURE 3 – Bacterial ooze emerging from pod lesions
Photo: R. Harveson, Univ. of Nebraska

AUTHOR: Robert M. Harveson

SYMPTOMS

• Symptoms occur on all above-ground plant parts
• Lesions initially are water-soaked and later turn necrotic
• Lesions are vein-delimited, angular in shape and translucent
• Bacterial ooze may be seen under conditions of high humidity

FACTORS FAVORING DEVELOPMENT

• Warm temperatures
• High humidity or leaf moisture

IMPORTANT FACTS

• Pathogens are seedborne
• Spread can occur with any type of mechanical contact on wet leaves or by splashing water
• Planting clean seed and use of disease resistant cultivars are the most effective management tools
• Can be confused with fungal leaf spots

Powdery mildew

Erysiphe pisi and E. trifolii

Figure 1Photo Wunsch - NDSU

FIGURE 1 – Small tufts of fungal growth
Photo: M. Wunsch, NDSU

Figure 2Photo Markell - NDSU

FIGURE 2 – Progression of fungal growth
Photo: S. Markell, NDSU

Figure 3Photo Markell - NDSU

FIGURE 3 – Fungal growth rubbed off right side of leaf
Photo: S. Markell, NDSU

Figure 4Photo Attanayake - WA State U

FIGURE 4 – Sever infection late in the season; note black fungal structures
Photo: R. Attanayake, Washington St. U.

AUTHORS: Renuka N. Attanayake, Weidong Chen and Michael Wunsch

SYMPTOMS

• White powdery tufts of fungal growth
• New fungal growth can be rubbed off easily
• Fungal growth will expand and may cause plant tissue to become chlorotic
• Late in the season, black fungal structures may appear
• Infection on pods can cause a gray-brown discoloration of the seeds

FACTORS FAVORING DEVELOPMENT

• Temperatures of 59 to 77 F are optimal
• Heavy dew or fog
• Late planting

IMPORTANT FACTS

• Pathogen can be soil-borne, seed-borne and wind-dispersed
• Management tools include resistant cultivars, crop rotation and foliar fungicides
• Most prevalent late in the season

Rust

Uromyces viciae-fabae

Figure 1Photo Markell - NDSU

FIGURE 1 – Pustules filled with dusty brown spores on leaf
Photo: S. Markell, NDSU

Figure 2Photo Markell - NDSU

FIGURE 2 – Pustules lacerating branch
Photo: S. Markell, NDSU

Figure 3Photo Markell - NDSU

FIGURE 3 – Severe infection causing premature senesce and plant death
Photo: S. Markell, NDSU

AUTHORS:Sam Markell and Julie Pasche

SYMPTOMS

• Affects all above-ground plant parts
• Pustules erupt from tissue, causing holes and large lacerations
• Pustules are filled with dusty cinnamon-brown spore that easily rub off
• Severe infection causes yellowing, premature senesce and yield loss

FACTORS FAVORING DEVELOPMENT

• Heavy dew or fog

IMPORTANT FACTS

• Disease observed annually in northern Great Plains but rarely widespread
• Epidemics can progress quickly once disease is established
• Foliar fungicides can help manage disease
• Also can infect lentils and garden peas

Septoria blight

Septoria pisi

Figure 1Photo Markell - NDSU

FIGURE 1 – Young leaf lesion with black fungal structures (pycnidia)
Photo: S. Markell, NDSU

Figure 2Photo Markell - NDSU

FIGURE 2 – Oblong lesions with pycnidia
Photo: S. Markell, NDSU

Figure 3Photo Markell - NDSU

FIGURE 3 – Necrotic lesion with pycnidia on branch
Photo: S. Markell, NDSU

AUTHORS: Mary Burrows and Sam Markell

SYMPTOMS

• Symptoms occur on all plant parts
• Necrotic lesions with small black fungal structures (pycnidia)
• Often occur late in the season

FACTORS FAVORING DEVELOPMENT

• Warm temperatures (70 to 80 F)
• High humidity or heavy dews

IMPORTANT FACTS

• The pathogen survives on crop stubble or infected seed; spores are wind-dispersed
• Planting clean seed, rotation and foliar fungicides are the most effective management tools
• No variety resistance is known
• Can be confused with Ascochyta blight and bacterial blight. Note that Septoria pycnidia are distributed randomly and Ascochyta pycnidia are distributed in a circular, target pattern. Bacterial blight does not have pycnidia.

White Mold

Sclerotinia sclerotiorum

Figure 1Photo McPhee - NDSU

FIGURE 4 – Apothecia (mushrooms) developed from sclerotia
Photo: K. McPhee, NDSU

AUTHORS: Weidong Chen, Lyndon Porter and Kevin McPhee

SYMPTOMS

• Lesions occur on stems, leaves and pods
• Lesions initially are water-soaked but appear bleached and necrotic as they age
• White, puffy fungal growth (white mold) may appear on lesions
• Mouse-dropping-sized black sclerotia may form on and in infected tissue

FACTORS FAVORING DEVELOPMENT

• Cool and moist conditions
• Lush vegetative growth
• Heavy canopy

IMPORTANT FACTS

• Sclerotia can survive for many years in soil
• Pathogen infects most broadleaf crops
• Plant-to-plant spread can occur by physical contact
• Management tools include clean seed, fungicide applications, rotation to cereal crops and irrigation management

Viruses

Alfalfa mosaic

Alfalfa mosaic virus

Figure 1Photo Porter - USDA-ARS

FIGURE 1 – Yellow mottling of foliar tissue
Photo: L. Porter, USDA-ARS Prosser, WA

AUTHORS:
Lyndon Porter

SYMPTOMS

• Yellow mottling of foliar tissue (not always prominent)
• Purple or brown streaks in leaf veins
• Dead tissue on leaf or stem

FACTORS FAVORING DEVELOPMENT

• Presence of pea and green peach aphids, which transmit the virus
• Proximity to alfalfa fields

IMPORTANT FACTS

• Pea, green peach, foxglove, bean and potato aphids transmit the virus
• No resistant cultivars are available
• Insecticides may reduce secondary spread of virus by killing vectors (aphids)
• Can be confused with pea streak virus

Bean leaf roll or pea leaf roll

Bean leaf roll virus

Figure 1Photo Porter - USDA-ARS 

FIGURE 1 – Yellow, distorted and twisted leaves
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 2Photo Porter - USDA-ARS

FIGURE 2 – Down-curled leaves
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 3Photo Porter - USDA-ARS

FIGURE 3 – Yellow and distorted new growth; old growth is normal
Photo: L. Porter, USDA-ARS Prosser, WA

AUTHORS: Lyndon Porter

SYMPTOMS

• Plants are yellow and stunted
• New tissue is distorted and twisted while old growth may be normal
• Leaflets curl downward and are brittle

FACTORS FAVORING DEVELOPMENT

• Presence of pea aphids transmitting the virus

IMPORTANT FACTS

• Virus is not seed-transmitted
• Often occurs with pea enation mosaic virus
• Later infections are less likely to have an impact on yield
• Cultivars with resistance may be available
• Can be confused with other viruses, root rots, herbicide damage or abiotic stress

Pea enation mosaic

Pea enation mosaic virus

Figure 1Photo Porter - USDA - ARS

FIGURE 1 – Leaf with mosaic pattern of white/clear spots (windows)
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 2Photo Porter - USDA-ARS

FIGURE 2 – Misshapen pods
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 3Photo Porter - USDA - ARS

FIGURE 3 – Enations (bumps) on leaf
Photo: L. Porter, USDA-ARS Prosser, WA

AUTHORS: Lyndon Porter

SYMPTOMS

• Leaves may be brittle and have a mosaic of green and yellow rough bumps (enations), translucent spots or clear veins
• Pods may be distorted and fill poorly

FACTORS FAVORING DEVELOPMENT

• Presence of pea aphids transmitting the virus

IMPORTANT FACTS

• Virus is not seed-transmitted
• Often occurs with bean leaf roll virus
• Early infections more severely impact yield than late infections
• Insecticides may reduce secondary spread of virus by killing vectors (aphids)
• Can be confused with other viruses, herbicide damage

Pea seedborne mosaic

Pea seedborne mosaic virus

Figure 1Photo Porter - USDA ARS

FIGURE 1 – Deformed growth
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 2Photo Beck - NDSU

FIGURE 2 – Seed with water soaking and scarring symptoms
Photo: A. Beck, NDSU

Figure 3Photo Wunsch - NDSU

FIGURE 3 – Delayed maturity of infected plants
Photo: M. Wunsch, NDSU

AUTHORS: Lyndon Porter, Kevin McPhee and Julie Pasche

SYMPTOMS

• Leaves may curl downward
• Plants are stunted with a rosette appearance on new growth
• Pods may be deformed and fill poorly
• Seed may be water-soaked, scarred or cracked
• Maturity of infected plants is delayed

FACTORS FAVORING DEVELOPMENT

• Presence of pea, green peach or potato aphids, which can transmit the virus
• Infected seed

IMPORTANT FACTS

• Virus is readily seed-transmitted
• Virus infects many plants, including lentil, chickpea, alfalfa and vetch
• Manage by planting virus-free seed and resistant cultivars
• Insecticides may reduce secondary spread of virus by killing vectors (aphids)
• Can be confused with other viruses or herbicide damage

Pea streak

Pea streak virus

Figure 1Photo Porter-USDA - ARS

FIGURE 1 – Malformed pea pods with blistering
Photo: L. Porter, USDA-ARS Prosser, WA

Figure 2Photo Porter - USDA-ARS

FIGURE 2 – Purple sunken streaks on infected plants
Photo: L. Porter, USDA-ARS Prosser, WA

AUTHORS:Lyndon Porter

SYMPTOMS

• Purple to brown streaks on leaves, stems and pods
• Leaf-yellowing and dieback of growing tips
• Pods may appear blistered, deformed and fill poorly
• Streaks on pods differ in size and shape and often are sunken

FACTORS FAVORING DEVELOPMENT

• Presence of pea or green peach aphid transmitting virus

IMPORTANT FACTS

• Virus is not seed-transmitted
• Virus also can infect alfalfa, red and white clover, and vetch
• Rarely associated with significant damage in pea fields
• Insecticides may reduce secondary spread of virus by killing vectors (aphids)
• Can be confused with other viruses, herbicide or abiotic damage

 May 2016

NDSU Ext Service          ND Ag Exp Station          USDA

Ag Research Service          North Central IPM Center

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