Title

Lentil Disease Diagnostic Series

(PP1913 Reviewed February 2024)
File
Publication File:
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

Table of Contents

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 progressing upward and premature death caused by F. avenaceum (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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