Title

Lentil Disease Diagnostic Series

(PP1913 Reviewed February 2024)
Summary

A continuation of the Disease diagnostic series cards, these are funded externally and will be distributed to growers and other stakeholders.

Lead Author
Lead Author:
Julie Pasche, Dry Bean and Pulse Crop Pathologist, North Dakota State University
Other Authors

Audrey Kalil, Plant Pathologist, Williston Research Extension Center, North Dakota State University; Samuel Markell, Extension Plant Pathologist, North Dakota State University

Availability
Availability:
Available in print from the NDSU Distribution Center.

Contact your county NDSU Extension office to request a printed copy.
NDSU staff can order copies online (login required).

Publication Sections

Pythium seed and seedling rot

Pythium ultimum, P. irregulare, P. aphanidermatum and other Pythium species

FIGURE 1 – Brown/black discoloration and pruning of lateral and tap roots by Pythium irregulare
Photo Credit:
T. Paulitz, USDA-ARS, Pullman, Wash.
FIGURE 1 – Brown/black discoloration and pruning of lateral and tap roots by Pythium irregulare
FIGURE 2 – Range of yellowing on plant foliage
Photo Credit:
T. Paulitz, USDA-ARS, Pullman, Wash.
FIGURE 2 – Range of yellowing on plant foliage

AUTHORS:Lyndon Porter, Timothy Paulitz and Kurt Schroeder

SYMPTOMS

• Poor emergence, rotted seed with light brown root discoloration
• Stunted plants with yellow or purple leaves developing from the bottom

FACTORS FAVORING DEVELOPMENT

• Cool, water-saturated or compacted soil and poor seed vigor

IMPORTANT FACTS

• Metalaxyl (mefenoxam)-resistant Pythium is present in some growing regions
• Effective seed treatments are available for metalaxyl-resistant and sensitive Pythium
• Avoid planting into wet or compacted soils
• Pathogen survives on plant debris and in soil
• Resistant varieties are not available
• Often occurs in complex with other root rots
• Can be confused with other root rots and water logging

Fusarium root rot

Fusarium avenaceum and other Fusarium species

FIGURE 1 – Brown to reddish-brown lesions on lower stems and roots caused by Fusarium infection
Photo Credit:
Photo: K. Zitnick-Anderson, NDSU
FIGURE 1 – Brown to reddish-brown lesions on lower stems and roots caused by Fusarium infection
FIGURE 2 – Infected seedlings
Photo Credit:
FIGURE 2 – Infected seedlings
FIGURE 2 – Infected seedlings
FIGURE 3 – Yellowing and premature death caused by F. avenaceum, showing diseased (middle/bottom) and healthy (top) roots.
Photo Credit:
Photo: L. Porter, USDA-ARS, Prosser, Wash.
FIGURE 3 – Yellowing progressing upward and premature death caused by F. avenaceum (diseased [middle/bottom] and healthy [top] roots)

AUTHORS: Audrey Kalil and Lyndon Porter

SYMPTOMS

• Poor emergence
• Wilting, stunting and premature death

FACTORS FAVORING DEVELOPMENT

• Soil compaction and plant stress
• Warm, moist soil (68 to 82 F)
• Short pea and lentil rotations

IMPORTANT FACTS

• Pathogen survives on plant debris and in soil
• Often occurs in complex with other root diseases
• Resistant varieties are not available
• Fungicide seed treatments may be recommended
• Can be confused with other root rots and water logging

Rhizoctonia seed, seedling and root rot

Rhizoctonia solani

FIGURE 1 – Sunken brown lesions on stem and root just below soil
Photo Credit:
Photo: K. Zitnick-Anderson, NDSU
FIGURE 1 – Sunken brown lesions on stem and root just below soil
FIGURE 2 – Moderate (top) to severe (bottom) Rhizoctonia root rot
Photo Credit:
Photo: K. Zitnick-Anderson, NDSU
FIGURE 2 – Moderate (top) to severe (bottom) Rhizoctonia root rot

AUTHORS: Jessica Rupp, Myron Bruce and Timothy Paulitz

SYMPTOMS

• Poor emergence
• Reddish-brown to dark brown lesions on roots and base of stem
• Secondary roots absent
• Plants are stunted and leaves turn yellow

FACTORS FAVORING DEVELOPMENT

• Wet, compacted or waterlogged soils

 IMPORTANT FACTS

• Pathogen survives on plant debris and in soil
• Resistant varieties are not available
• Fungicide seed treatments may be recommended
• Often occurs in a complex with other root rots
• Can be confused with other root rots and water logging

Aphanomyces root rot

Aphanomyces euteiches

FIGURE 1 – Infected roots with caramel-brown root rot (R), compared with healthy roots (L)
Photo Credit:
Photo: L. Porter, USDA-ARS, Prosser, Wash.
FIGURE 1 – Infected roots with caramel-brown root rot (R), compared with healthy roots (L)
FIGURE 2 – Infection moving up primary stem
Photo Credit:
Photo: L. Porter, USDA-ARS, Prosser, Wash.
FIGURE 2 – Infection moving up primary stem

AUTHORS: Lyndon Porter

SYMPTOMS

• Root rot may extend slightly above the soil line
• Leaf yellowing progresses from lower canopy upward
• Early season stunting and premature plant death

FACTORS FAVORING DEVELOPMENT

• Cool, wet spring conditions
• High soil moisture
• Short rotations with peas and lentils

 IMPORTANT FACTS

• Chickpea, cereals and faba bean are not important hosts
• Often occurs in a complex with other root rot diseases
• Can survive for many (20) years in soil without a susceptible host
• Seed treatments and genetic resistance are not effective
• Can be confused with other root rots and water logging

Anthracnose

Colletotrichum species

FIGURE 1 – Small black fungal resting structures (microsclerotia) within anthracnose lesions
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1 – Small black fungal resting structures (microsclerotia) within anthracnose lesions
FIGURE 1a – Small black fungal resting structures (microsclerotia) within anthracnose lesions
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1a – Small black fungal resting structures (microsclerotia) within anthracnose lesions
FIGURE 2 – Severe anthracnose lesions coalescing
Photo Credit:
Michael Wunsch, NDSU
FIGURE 2 – Severe anthracnose lesions coalescing
FIGURE 3a – Anthracnose-infected pods and discolored seeds
Photo Credit:
Michael Wunsch, NDSU
FIGURE 3a – Anthracnose-infected pods and discolored seeds
FIGURE 3b – Anthracnose-infected pods and discolored seeds
Photo Credit:
Michael Wunsch, NDSU
FIGURE 3b – Anthracnose-infected pods and discolored seeds

AUTHORS: Michael Wunsch and Julie Pasche

SYMPTOMS

• Light-brown stem lesions with a dark border
• Symptoms initiate at the base of plant and spread upward
• Patches of dead plants develop when stem lesions girdle plant

FACTORS FAVORING DEVELOPMENT

• Abundant rainfall during bloom and pod development
• Wide range of temperatures; 68 to 74 F optimal
• Dense canopy

IMPORTANT FACTS

• Seed quality declines with increasing anthracnose severity
• Varieties differ in susceptibility to anthracnose; none are resistant
• No-till increases degradation of pathogen resting structures
• Commonly confused with Ascochyta blight

Ascochyta blight

Ascochyta lentis

FIGURE 1a – Concentric ring pattern from pycnidia inside the light brown lesion
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1a – Concentric ring pattern from pycnidia inside the light brown lesion
FIGURE 1b – Concentric ring pattern from pycnidia inside the light brown lesion
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1b – Concentric ring pattern from pycnidia inside the light brown lesion
FIGURE 2 – Mid-canopy Ascochyta blight lesions
FIGURE 2 – Mid-canopy Ascochyta blight lesions
FIGURE 3a – Discolored seeds produced in pods with Ascochtya lesions
Photo Credit:
Michael Wunsch, NDSU
FIGURE 3a – Discolored seeds produced in pods with Ascochtya lesions
FIGURE 3b – Discolored seeds produced in pods with Ascochtya lesions
Photo Credit:
Michael Wunsch, NDSU
FIGURE 3b – Discolored seeds produced in pods with Ascochtya lesions

AUTHORS:Michael Wunsch and Julie Pasche

SYMPTOMS

• Light brown leaf, stem and pod lesions with dark brown borders
• Small brown fungal fruiting structures (pycnidia) within lesions
• Disease lesions and/or picnidia within lesions often exhibit a concentric ring pattern (unlike anthracnose)
• Flower and pod abortion

FACTORS FAVORING DEVELOPMENT

• Cool, wet weather; 50 to 68 F optimal
• Planting lentils immediately adjacent to a field where Ascochyta blight occurred on lentils the previous year

IMPORTANT FACTS

• Ascochyta blight is seed-borne and seed-transmitted; seed should be tested
• Managed with crop rotation (minimum two years out of lentils) and foliar fungicides
• Commonly confused with anthracnose

Botrytis gray mold

Botrytis cinerea, B. fabae

FIGURE 1a – Gray sporulation on diseased tissues when relative humidity is high
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1a – Gray sporulation on diseased tissues when relative humidity is high
FIGURE 1b – Gray sporulation on diseased tissues when relative humidity is high
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1b – Gray sporulation on diseased tissues when relative humidity is high
FIGURE 1c – Gray sporulation on diseased tissues when relative humidity is high
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1c – Gray sporulation on diseased tissues when relative humidity is high
FIGURE 2 – Dead patches in lentil field
Photo Credit:
Michael Wunsch, NDSU
FIGURE 2 – Dead patches in lentil field

AUTHORS:Michael Wunsch and Julie Pasche

SYMPTOMS

• Gray fungal growth on diseased stems, leaves and pods in the lower canopy
• Plant tissue is light brown to bleached
• Plants become chlorotic, wilt and die when lesions girdle the lower stem
• Plant-to-plant spread of Botrytis is common, resulting in dead patches

FACTORS FAVORING DEVELOPMENT

• Dense crop canopies that restrict airflow
• High relative humidity and frequent rainfall
• Cool temperatures; 59 to 77 F optimal

IMPORTANT FACTS

• Resistant varieties are not available
• Fungicides can be effective if applied preventatively
• Commonly confused with white mold and anthracnose

Stemphylium blight

Stemphylium botryosum

FIGURE 1a – Tan to light brown lesions at disease onset
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1a – Tan to light brown lesions at disease onset
FIGURE 1b – Tan to light brown lesions at disease onset
Photo Credit:
Michael Wunsch, NDSU
FIGURE 1b – Tan to light brown lesions at disease onset
FIGURE 2a – Diseased leaflets that have become dark brown to gray due to pathogen sporulation under high relative humidity
Photo Credit:
Michael Wunsch, NDSU
FIGURE 2a – Diseased leaflets that have become dark brown to gray due to pathogen sporulation under high relative humidity
FIGURE 2b – Diseased leaflets that have become dark brown to gray due to pathogen sporulation under high relative humidity
Photo Credit:
Michael Wunsch, NDSU
FIGURE 2b – Diseased leaflets that have become dark brown to gray due to pathogen sporulation under high relative humidity
FIGURE 3a – Defoliated plants that have shed diseased leaves
Photo Credit:
Michael Wunsch, NDSU
FIGURE 3a – Defoliated plants that have shed diseased leaves
FIGURE 3b – Defoliated plants that have shed diseased leaves
Photo Credit:
Michael Wunsch, NDSU
FIGURE 3b – Defoliated plants that have shed diseased leaves

AUTHORS:Weidong Chen and Michael Wunsch

SYMPTOMS

• Leaflets may exhibit angular lesions at disease onset
• Disease is most severe on leaves but also infects pods, stems and petioles

FACTORS FAVORING DEVELOPMENT

• Extended periods of high relative humidity in the last third of the growing season
• Warm temperatures; 77 to 86 F optimal

IMPORTANT FACTS

• Red lentils are generally more susceptible than green lentils
• Managed with fungicides and partially resistant varieties
• Can be confused with nutrient deficiencies (such as low nitrogen) or plant senescence

Bacterial blight

Pseudomonas syringae pv. syringae

FIGURE 1 – Brown, circular and translucent foliar lesions
Photo Credit:
F. Mathew, South Dakota State University
FIGURE 1 – Brown, circular and translucent foliar lesions
FIGURE 2 – Bacterial ooze from pod lesions
Photo Credit:
R. Harveson, University of Nebraska
FIGURE 2 – Bacterial ooze from pod lesions

AUTHORS:Febina Mathew, Bob Harveson and Bright Agindotan

SYMPTOMS

• Lesions observed on all above-ground plant parts
• Initial lesions are water-soaked and become necrotic through time
• Bacteria may ooze from lesions under high-humidity conditions

FACTORS FAVORING DEVELOPMENT

• Warm temperatures
• High humidity or moisture on leaves
• Hail

IMPORTANT FACTS

• Bacteria can be spread by rain, wind and mechanical means
• P. syringae pv. syringae can cause disease on soybean, dry edible beans and other legumes
• Physical damage (such as hail) can facilitate infection and spread
• Fungicides are not effective
• Planting infected seed can increase disease risk
• Can be confused with Ascochyta blight or anthracnose

Powdery mildew

Erysiphe pisi and Leveillula taurica

FIGURE 1 – Early infection - white “powdery” spots
Photo Credit:
L. Porter, USDA-ARS, Prosser, Wash.
FIGURE 1 – Early infection - white “powdery” spots
FIGURE 2 – Leaf and stem surfaces covered with powdery mildew
Photo Credit:
L. Porter, USDA-ARS, Prosser, Wash.
FIGURE 2 – Leaf and stem surfaces covered with powdery mildew
FIGURE 3 – Feltlike white fungal growth
Photo Credit:
W. Chen, USDA-ARS, Pullman, Wash.
FIGURE 3 – Feltlike white fungal growth

AUTHORS:Lyndon Porter and Weidong Chen

SYMPTOMS

• Most visible starting at flowering and later in the season
• Infected leaves can become chlorotic/necrotic and curled
• Infection begins as small spots that enlarge quickly and cover plant surfaces

FACTORS FAVORING DEVELOPMENT

• Late planting
• Conditions limiting sunlight
• Temperatures of 59 to 77 F are optimal

IMPORTANT FACTS

• Pathogen can be soil-borne, seed-borne and wind-dispersed
• Fungicides may be effective if applied early in disease development
• Crop rotation is important
• Lentil varieties have differing levels of resistance
• Can be confused with white mold and the fungal growth of saprophytes or other pathogens

White mold (Sclerotinia stem rot)

Sclerotinia sclerotiorum

FIGURE 1 – Dead patches of plants
Photo Credit:
W. Chen, USDA-ARS, Pullman, Wash.
FIGURE 1 – Dead patches of plants
FIGURE 2 – White, fluffy fungal growth on leaves and stems
Photo Credit:
L. Dighans, Pro Co-op Ag Center, Scobey, Mont.
FIGURE 2 – White, fluffy fungal growth on leaves and stems
FIGURE 3 – Bleached lesions with white fungal growth
Photo Credit:
W. Chen, USDA-ARS, Pullman, Wash.
FIGURE 3 – Bleached lesions with white fungal growth
FIGURE 4 – Dark, hard fungal structures (sclerotia) on the soil surface
Photo Credit:
W. Chen, USDA-ARS, Pullman, Wash.
FIGURE 4 – Dark, hard fungal structures (sclerotia) on the soil surface

AUTHORS:Mary Burrows, Weidong Chen and Michael Wunsch

SYMPTOMS

• First observed as water-soaked lesions
• Lesions enlarge and become bleached
• White fluffy fungal growth may appear under high humidity
• Hard, black sclerotia may appear late in the season
• Wilting

FACTORS FAVORING DEVELOPMENT

• Cool, wet conditions after canopy closure
• Short rotations with susceptible crops
• Lush canopy

IMPORTANT FACTS

• Sclerotia survive in the soil for several years
• Pathogen infects most broadleaf plants
• Fungicides can be effective if applied preventatively
• Can be confused with powdery mildew, nutrient deficiencies (low nitrogen) or plant senescence

Pea enation mosaic

Pea enation mosaic virus (PEMV)

FIGURE 1 – Twisted and malformed leaves
Photo Credit:
W. Chen, USDA-ARS, Pullman, Wash.
FIGURE 1 – Twisted and malformed leaves
FIGURE 2 – Leaf mottling
Photo Credit:
W. Chen, USDA-ARS, Pullman, Wash.
FIGURE 2 – Leaf mottling
FIGURE 3 – Leaf mottling
Photo Credit:
W. Chen, USDA-ARS, Pullman, Wash.
FIGURE 3 – Leaf mottling

AUTHORS:Lyndon Porter, Bright Agindotan and Kevin McPhee

SYMPTOMS

• Small, circular to elongated translucent spots or streaks on leaves
• Vein clearing
• Stunted growth and malformed pods

FACTORS FAVORING DEVELOPMENT

• Presence of aphid vectors, including pea, cowpea, green peach, potato or foxglove
• Movement of aphids from virus-infected overwintering hosts in the spring or alfalfa fields during cuttings

IMPORTANT FACTS

• Can infect chickpea, pea, faba bean, vetch, crimson clover and lambsquarters
• PEMV is not seed-transmitted
• No known resistant varieties
• Insecticides applied to manage aphid vector may help reduce secondary spread
• Can be confused with other viruses or damage from herbicides or thrips

Bean leaf roll

Bean leaf roll virus (BLRV)

FIGURE 1 – Early leaf yellowing symptoms
Photo Credit:
B. Agindotan, Montana State University, Bozeman
FIGURE 1 – Early leaf yellowing symptoms
FIGURE 2 – Advanced stage of yellowing (Infected [L, R] and healthy [C])
Photo Credit:
B. Agindotan, Montana State University, Bozeman
FIGURE 2 – Advanced stage of yellowing (Infected [L, R] and healthy [C])

 AUTHORS: Bright Agindotan and Lyndon Porter

SYMPTOMS

• Yellowing and stunting
• Small leaves

FACTORS FAVORING DEVELOPMENT

• Presence of other BLRV-infected legume crops and weeds
• Presence of aphid vectors, including pea, cowpea, potato and vetch
• Movement of aphids from alfalfa fields during cuttings

IMPORTANT FACTS

• Leaf rolling absent
• BLRV is not seed-transmitted
• BLRV infects pea, chickpea, lentil, alfalfa and other legumes
• Insecticides applied to manage aphid vectors may help reduce secondary spread
• Resistant varieties may be available
• Can be confused with nutrient deficiencies (low nitrogen) or plant senescence

January 2019

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