Chickpea Disease Diagnostic Series

Pythium and Globisporangium species

AUTHORS: Weidong Chen and Lyndon D. Porter

SYMPTOMS

• Rotten seeds coated with hard-to-remove soil
• Infected seeds and root tissue are light brown in color
• Bare patches where plants fail to emerge
• Emerged plants are chlorotic, stunted, with poor vigor

Photo Credit:

W. Chen, USDA-ARS, Pullman, Wash.

Figure 1: Infected root radical and infected seed tissue coated in soil

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash.

Figure 2: Washed infected seed

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash.

Figure 3: Infected roots with pinching-off of secondary roots and discoloration

FACTORS FAVORING DEVELOPMENT

• Planting into cool (below 50 degrees Fahrenheit) and compacted soils
• Deep seeding (more than 2 inches)
• Poor quality/old seed
• Soil is water-saturated at or soon after planting

IMPORTANT FACTS

• Manage with metalaxyl seed treatment, shallow seeding in warm soils and planting high vigor seed
• Effective seed treatments are available for metalaxyl-resistant Pythium
• Kabuli varieties are more susceptible than desi
• Resistant kabuli varieties are not available
• Commonly confused with Fusarium and Rhizoctonia root rot and water logging

Rhizoctonia solani

AUTHORS: Michael Wunsch and Erin E. Gunnink Troth

SYMPTOMS

• Seed decay and damping-off, resulting in poor emergence
• Sunken reddish to brown lesions on the epicotyl and tap root
• Distribution may be patchy to widespread in a field

Photo Credit:

M. Wunsch, NDSU

Figure 1: Reduced stand establishment and plant vigor resulting from high Rhizoctonia pathogen pressure

Photo Credit:

M. Wunsch, NDSU

Figure 2: Cotyledon rot and a sunken lesion at the seed attachment site

Photo Credit:

M. Wunsch, NDSU

Figure 3: Older lesions turn black as secondary microbes invade diseased tissues

FACTORS FAVORING DEVELOPMENT

• Cool, wet soils
• Damage from herbicide carryover

IMPORTANT FACTS

• Plant residues and soil can harbor the pathogen
• Wide host range includes faba bean, dry bean, field pea, lentil, soybean, canola and sunflower
• Fungicide seed treatments are highly effective, particularly SDHI (FRAC 7) fungicides
• Commonly confused with other root rots and often occurs in a complex with them

Macrophomina phaseolina

AUTHORS: Malaika Ebert and Muthappa Senthil-Kumar

SYMPTOMS

• Rapidly dying plants scattered throughout the field during reproductive growth stages
• Taproot dry and dark without lateral roots
• Lower taproot often missing, easy to uproot plants

Photo Credit:

M. Senthil-Kumar, NIPGR

Figure 1: Field symptoms with straw-colored plants (arrow)

Photo Credit:

M. Senthil-Kumar, NIPGR

Figure 2: Diseased plants are straw-colored with brittle and rotten primary taproot

Photo Credit:

M. Senthil-Kumar, NIPGR

Figure 3: Black microsclerotia on the exterior and interior of the stem (arrow)

FACTORS FAVORING DEVELOPMENT

• Hot and dry conditions, with daily minimum above 68 degrees Fahrenheit and maximum above 86 degrees Fahrenheit
• Drought stress
• Poor or sandy soil

IMPORTANT FACTS

• Pathogen is seedborne, soilborne and survives on infected residue as microsclerotia
• Resistant cultivars are available
• Survives in soil for more than 12 months
• Fungicide seed treatment or preventative foliar fungicides help manage disease
• Pathogen has a broad host range of over 500 plant species, including many legumes
• May be confused with Fusarium wilt and other root rots

Fusarium species

AUTHOR: Lyndon D. Porter

SYMPTOMS

• Yellowing and necrosis of foliage at plant base and moving upwards
• Dark black, reddish or brown root rot beginning at seed attachment point and spreading to roots
• Stunting
• Symptoms can develop early but are most pronounced at flowering

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash

Figure 1: Black discoloration of infected roots and progressive yellowing of foliage from base upwards

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash.

Figure 2: Loss of secondary roots (middle plant)

FACTORS FAVORING DEVELOPMENT

• Compacted soil and plant stress
• Short chickpea crop rotations (two-year rotations)
• Warm, moist soil (68 to 82 degrees Fahrenheit)

IMPORTANT FACTS

• Pathogen survives in soil and on seed
• Often associated with other root rots
• No known cultivars with complete resistance
• Alternate hosts include peas and lentils
• Commonly confused with Rhizoctonia and Black streak root rots

Fusarium oxysporum f. sp. ciceri

AUTHOR: Lyndon D. Porter

SYMPTOMS

• Symptoms typically appear at flowering
• Drooping, wilted, dull-green leaves
• Leaf symptoms may be more severe on one side of the plant than the other

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash

Figure 1: Scattered distribution of infected plants dying in the field

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash.

Figure 2: Leaf yellowing, wilting and death progresses from lower canopy upward

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash.

Figure 3: Dark brown to black vascular stem tissue near plant base

FACTORS FAVORING DEVELOPMENT

• Warm soil temperatures (77 to 86 degrees Fahrenheit), especially during early growth stages
• Short chickpea crop rotations (two-year or less)
• Planting infected seed and susceptible cultivars

IMPORTANT FACTS

• Races 0, 1A, 1B/C, 5 and 6 are found in the U.S.
• Cultivars vary in resistance to different races
• Pathogen has two pathotypes, one causes slow yellowing, the other wilt
• Commonly confused with Fusarium root rot and abiotic stresses such as waterlogging

Verticillium dahliae and Verticillium albo-atrum

AUTHORS: Dimitri Fonseka, Julie Pasche and Malaika Ebert

SYMPTOMS

• Leaves turn yellow, wilt and eventually die
• Light brown discoloration of vascular tissue in the stem

Photo Credit:

M. Ebert, NDSU

Figure 1: Yellowing of leaves and dead leaf tissue

Photo Credit:

M. Ebert, NDSU

Figure 2: Uneven necrosis of leaflets moving up stem

Photo Credit:

M. Ebert, NDSU

Figure 3: Light-brown discoloration of the vascular tissue (arrow)

FACTORS FAVORING DEVELOPMENT

• Warm, moist soils (61 to 68 degrees Fahrenheit)
• Warm air temperatures (72 to 82 degrees Fahrenheit)
• Planting susceptible cultivars

IMPORTANT FACTS

• The pathogen is spread in irrigation water, on farm machinery and via infested seed
• Verticillium can survive in the soil for up to 10 years
• Verticillium has a broad host range which includes woody and herbaceous plants. Rotation to non-host crops (small grains) is recommended
• Sanitation of farm equipment between fields reduces spread
• Commonly confused with Fusarium wilt and drought stress

Ascochyta rabiei

AUTHOR: Weidong Chen

SYMPTOMS

• Leaf lesions are initially water-soaked, irregular flecks and/or circular to oval lesions, with concentric ring pattern of small brown pycnidia
• Stem lesions develop at nodes, elongate and cause stem breakage
• Shriveled seed with brown discoloration

Photo Credit:

A. Kalil, NDSU and W. Chen, USDA-ARS, Pullman, Wash

Figure 1: Leaf lesion with pycnidia and watersoaked border

Photo Credit:

A. Kalil, NDSU

Figure 2: Ascochyta blight lesion girdling the stem

Photo Credit:

A. Kalil, NDSU

Figure 3: Pod lesion with concentric rings of pycnidia

FACTORS FAVORING DEVELOPMENT

• Moderate temperatures (60 to 77 degrees Fahrenheit) and frequent rainfall
• Short rotation interval between chickpea crops
• Planting chickpea adjacent to where chickpea was planted the previous year

IMPORTANT FACTS

• Pathogen survives in crop residue and is seed-borne
• Pathogen host range is limited to chickpeas
• Strobilurin (QoI) fungicide resistance has been documented
• Plant disease-free seed with fungicide seed treatment
• Managed with minimum three-year crop rotation, less susceptible cultivars and timely application of foliar fungicides

Alternaria alternata

AUTHOR: Malaika Ebert

SYMPTOMS

• Symptoms occur on all above-ground plant parts
• Small, water-soaked, circular lesions turn reddish brown to purple
• Infected flowers and leaves may turn straw-colored before falling off
• Infected seed is shriveled and blackened
• In moist conditions, infected plants appear black from fungal sporulation

Photo Credit:

M. Wunsch, NDSU

Figure 1: Reddish-brown lesions on stems and leaves with yellowing and dead tissue

Photo Credit:

M. Wunsch, NDSU

Figure 2: Foliar symptoms of Alternaria blight

FACTORS FAVORING DEVELOPMENT

• Planting infected seed and susceptible cultivars
• Warm temperatures (75 to 82 degrees Fahrenheit) and high humidity (above 85%)
• Older plants are more susceptible

IMPORTANT FACTS

• Pathogen has broad host range including lentil, pea, mungbean and cowpea
• Pathogen survives in seed for up to 20 months
• Infected seed may be unfit for human or livestock consumption
• Manage with disease-free seed, resistant cultivars and seed and foliar applied fungicides
• May be confused with Ascochyta or Stemphylium blight

Stemphylium species

AUTHOR: Uta McKelvy

SYMPTOMS

• Develops as large irregular patches in the field
• Older leaf lesions may develop yellow or gray borders
• Leaf loss may occur
• Small, elongated, brown spots on the stems

Photo Credit:

M. Burrows, MSU

Figure 1: Initial lesions are small, roughly circular and brown

Photo Credit:

M. Burrows, MSU

Figure 2: Leaf lesions merge, develop irregular shapes and cover large areas

FACTORS FAVORING DEVELOPMENT

• Cool temperatures (59 to 68 degrees Fahrenheit) and high humidity
• Excessive vegetative growth
• Disease usually develops at and after flowering

IMPORTANT FACTS

• Disease is present in the U.S. but is of minor importance
• Pathogen is transmitted on/in residue, soil and seed
• No fungicides are registered for disease control
• May be confused with Alternaria blight and Ascochyta blight

Sclerotinia sclerotiorum, S. minor and S. trifoliorum

AUTHOR: 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

Photo Credit:

M. Wunsch, NDSU

Figure 1: Premature senescence of plant caused by a lesion girdling the stem

Photo Credit:

M. Wunsch, NDSU

Figure 2: Sclerotinia stem rot lesions typically exhibit a bleached coloration

Photo Credit:

M. Wunsch, NDSU

Figure 3: Round sclerotia

FACTO FAVORING DEVELOPMENT

• Cool, wet weather particularly after canopy closure
• Dense canopy
• Tight crop rotations with other susceptible crops including other legumes, sunflower and canola

IMPORTANT FACTS

• The pathogen persists in the soil as sclerotia for many years
• Sclerotinia stem rot often develops concurrently with Ascochyta blight and Botrytis gray mold
• Fungicides must be applied preventatively for successful Sclerotinia stem rot management Fungicides have no efficacy against Sclerotinia crown rot

Botrytis cinerea

AUTHORS: Michael Wunsch and Audrey Kalil

SYMPTOMS

• Water-soaked lesions on leaves, stems, flowers and pods that turn gray to dark brown
• Fluffy, gray mold produced under humid conditions
• Flower drop and seed abortion

Photo Credit:

M. Wunsch, NDSU

Figure 1: High humidity promotes abundant gray sporulation on lesions

Photo Credit:

M. Wunsch, NDSU

Figure 2: Stem symptoms include brown speckling and lesions that girdle the stem

Photo Credit:

M. Wunsch, NDSU

Figure 3: Diseased pods are initially brown and become gray from sporulation when humid

FACTORS FAVORING DEVELOPMENT

• Planting infested seed
• Dense crop canopy
• High humidity (above 95%) and moderate temperatures (68 to 77 degrees Fahrenheit)

IMPORTANT FACTS

• Pathogen has a wide host range of more than 100 plant species
• Pathogen is seedborne, survives in the soil and on infected plant residue
• Disease progresses rapidly
• Foliar fungicides have poor efficacy due to difficulty achieving good coverage inside the canopy
• Seed treatment with effective fungicides reduces seed to seedling transmission

Pea enation mosaic virus (PEMV)

AUTHOR: Lyndon D. Porter

SYMPTOMS

• Small spots or flecks on leaves
• Severe stunting
• Leaves and pods are malformed

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash.

Figure 1: “Windows” of yellow spots and streaks on distorted and curled leaves and close-up of “windows” on leaflets

Photo Credit:

L. Porter, USDA-ARS, Prosser, Wash.

Figure 2: Close-up of distorted leaflets with PEMV (see arrows)

FACTORS FAVORING DEVELOPMENT

• Virus-carrying aphids, such as the pea aphid, present and feeding on plants
• Warm spring temperatures favoring early aphid development and migration
• Infections at early growth stages are more severe

IMPORTANT FACTS

• All currently available commercial cultivars are susceptible to PEMV
• PEMV is not seed-transmitted
• Insecticides to manage aphids may reduce secondary spread of PEMV
• Pea, lentil, faba bean and vetch are also susceptible
• Commonly confused with thrips, herbicide or other virus damage