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Chickpea Diseases

Disease prevention

There are only a few diseases that significantly reduce yield and quality in chickpeas. These diseases can be minimized through preventative management. 

Disease prevention recommendations include:

  1. Crop Rotation: It is important to keep at least three years between the same type of pulse crop to allow for breakdown of crop residue on which disease pathogens survive. Longer rotations may be required for some pathogen, due to long-lived resting spores in the soil. Since there are diseases that affect more than one type of pulse crop, it is important to maintain at least two years between different pulse crops.  (Saskatchewan Government 2020 Guide to Crop Protection, page 421)
  2. Field Choice: Avoid planting chickpeas adjacent to previous year’s chickpea fields to reduce spread of residue and wind-borne spores and use non-host strips at field edges. Field selection should be at least 500 metres away from fields that had a chickpea crop the previous season.
  3. Type of Chickpea: Choose class based on risk of Ascochyta. Kabuli chickpeas are much more susceptible to Ascochyta Blight compared to Desi chickpeas. Unifoliate Kabuli varieties appear to be much more susceptible to severe Ascochyta Blight, compared to fern leaf Kabuli. 
  4. Variety Choice: Choose varieties that are as disease resistant as possible. Refer to provincial seed guides for varieties adapted to your region. When available, choose varieties with disease resistance.
  5. Seed Quality: Use of high quality seed is extremely important for successful chickpea production. It is important to have the seed tested by a seed-testing laboratory for germination, purity, and seed-borne disease. Seed-borne Ascochyta easily transmits to seedling in the field and only seed with close to 0% seed-borne Ascochyta, or levels below 0.3% Ascochyta infection. Even though a seed test may indicate 0% infection, the seed lot may contain infect seed and thus seed treatment is recommended.
  6. Seeding Rate: Target optimum plant densities (Kabuli 38 to 44 plants/m2, 3 to 3.3 plants/ft2, Desi 44 to 50 plants/m2 or 3.3 to 4.5 plants/ft2). Increasing plant density above the recommended range with highly susceptible varieties may increase disease severity.
  7. Fungicide Use: First application at early seedling stage (use earliest label staging) is critical to prevent or slow early development. Follow-up field scouting and additional fungicide applications may be necessary.
  8. Scout Often: Begin at the seedling stage, two to three weeks after seeding. Scout every three to seven days during the seedling stage. Rain and/or high humidity means scouting frequency should be increased. If conditions are drier and the chickpea plant gets past the seedling stage, scouting frequency can be decreased to every seven to 10 days.

Scouting your field for diseases

Scouting is one of the most powerful practices to effectively manage crops.  It allows early detection of disease symptoms, provides opportunity for mitigation of spread and minimizes the impact on yield.

  • Develop a systematic approach beginning soon after crop emergence.
  • ALWAYS bring along a shovel to dig up plants, pulling plants will not work when assessing root and nodule health.
  • Scout weekly beginning after the crop emerges until maturity, first looking at plant stand, then root/seedling diseases, and as the crop develops for foliar diseases.
  • Take photos, mark problem areas in the field, collect whole plants (leaves, stems and roots) for identification of the disease (put in plastic Ziploc, label with date and location and keep cool until sent to lab).
  • Check in a ‘W’ shaped pattern in the field stopping at 5-10 locations,
  • Take note of yellowing patches, and problem areas in the field. These are often the source of disease spread and if recurring problems are noted these areas may benefit from a separate management strategy.

Scouting, Government of Alberta

Plant Disease Scouting 101, Government of Saskatchewan Fact Sheet.  

Fungicide Application

Keeping crops healthy and disease free is a priority for producers and one practice that can help achieve these goals is applying fungicide. Producers need to consider both disease risk and economics when deciding whether to apply a fungicide.

Disease risk is influenced by the field history (crop rotation, levels of disease in previous susceptible crops; the environmental conditions such as temperature and precipitation levels that may favour disease development; and the level of variety resistance to the disease. A fungicide should only be applied if the risk of disease is high and an economic return is expected. 

Once a decision has been made to apply fungicide, the two most important considerations are timing and coverage. Plant growth and disease progress can be very rapid so it’s essential to be ready to apply the fungicide when it’s needed. Missing the ideal window is very costly and a fungicide applied at the wrong time can lose much of its effectiveness.

Good coverage is also critical for a fungicide to be effective. To achieve this, target the plant part that needs protection, be it the leaves, stems, or leafstalks, and do so with adequate droplet density. This is because most fungicides do not move from one part of the plant to another very well. That is why it is important to understand the disease, including which plant parts must be covered by spray and where – top, middle, or bottom – they are in the canopy. Then assess how easy it will be for a spray to reach the target zone.

Determine if more than one application should be done by scouting. If applying more than one application, make sure to rotate fungicide groups and do not use a single mode of action more than once. Consult the product’s label. (Forsythe, Trudy K. “Timing and Coverage are Important Factors in Fungicide Application”

Management of Fungicide Resistance

Management of fungicide resistance is extremely important for Ascochyta in chickpeas due to the genetic diversity of the pathogen. Some isolates with resistance to strobilurin fungicides have been confirmed in Western Canada. If a pathogen is resistant to one fungicide in the strobilurin group, it will be resistant to other fungicides in that group.

To delay fungicide resistance/insensitivity

The following guidelines, adopted from the North American Fungicide Resistance Action Committee, are recommended to prevent the increase of fungicide-resistant fungi:

  • Do not use a fungicide that contains only a strobilurin active unless it is tank mixed with a non-strobilurin fungicide.
  • Rotate the use of a fungicide with a strobilurin product in the mix (or tank mixed) with a non-strobilurin product.
  • Do not use more than two applications per year of any fungicide containing a strobilurin on the same field.
  • Do not apply more than two applications of the same group in a single growing season (except for chlorothalonil, which can be applied three times).

Top Diseases Impacting Chickpeas

  • Ascochyta/Mycosphaerella Blight
  • Root Rot Diseases
  • Botrytis Grey Mould
  • Sclerotinia White Mould (Sclerotinia Rot)

 

Ascochyta Mycosphaerella Blight

Ascochyta Blight on Chickpea Leaf, Photo Credit: Bugwood.org

Ascochyta Blight on Chickpea Leaf close up, Photo Credit: Bugwood.org

CAUSED BY
  • Ascochyta in chickpeas is caused by the Ascochyta complex containing three fungi: Mycosphaerella pinodes, which causes leaf, stem, and pod spot and foot rot; Ascochyta pisi Lib., which causes leaf, stem, and pod spot; and Phoma medicaginis var. pinodella, which causes leaf spot, stem lesions and foot rot.
  • The pathogen for this chickpea disease can survive on stubble for many years.
  • This pathogen prefers cool temperatures and high humidity in the canopy.
  • This pathogen is spread by both rain-splashed spores, and air-borne spores.
  • The pathogen overwinters on chickpea residue and seed. Both asexual spores and sexual spores can be produced on the residue. The sexual stage produces ascospores, which can spread several miles in the wind and are believed to be responsible for early season lesions.

SYMPTOMS
  • Symptoms of Ascochyta Blight include tan or brown lesions surrounded by a dark margin on stem, leafs, and pods. Tiny black specks known as pycnidia occur in the centre of the spot. Dark fruiting bodies, called pycnidia, are formed in the lesions. The pycnidia ooze spores in wet and humid conditions. Spores are spread by rain and thus infection is aided by weather with frequent showers.
  • Plants will show lesions approximately four to seven days following infection.
  • The lesions may girdle entire stems, causing them to wilt and die. Branch tips wilt, turn brown, and often die; premature drop occurs from infected leaflets. Ascochyta in chickpeas can also cause flower and pod abortions.
  • Infected seeds turn purplish-brown and are often shrivelled and smaller in size.
  • Plants will show lesions approximately four to seven days following infection.
  • Under drier conditions, the concentric ring pattern of the symptoms is less pronounced and may show up only as a uniform yellowing of lower leaves. Infected plants may survive, but will be delayed in maturity and produce lower yields.

PREVENTION AND CONTROL
  • Ascochyta Blight is also seed-borne, so the use of disease-free seed is critical. Ascochyta Blight is also capable of surviving for several years on crop residues in the soil.
  • A minimum four-year crop rotation will reduce the risk and will allow for the breakdown of chickpea residue on which the disease survives.
  • Use disease-free, treated seed. The seed can also be treated with various fungicides. New seed treatments are continually being registered. Avoid seeding next to the previous year’s pulse fields.
  • Post-emergent fungicides can be applied prior to flowering and can be repeated up to three times if conditions favour disease development.
  • Selection of a mostly weed-free field is essential, as few herbicides are registered for use on chickpea. Perennial weeds should be controlled in the years prior to chickpea production. It is important to record herbicide use each year and to avoid seeding chickpea in fields with soil residual herbicides. 
  • The breakdown of Ascochyta-blight-infected residue can be accelerated by incorporation into the soil. 
  • For more assistance in managing Ascochyta Blight in chickpeas see the resource below.

IMPACT
  • Ascochyta Blight is the number one disease impacting chickpeas.
  • The disease is very aggressive and can spread quickly in a field once established.
  • Ascochyta Blight can impact a chickpea crop with up to 90% yield loss in Kabuli and 50% yield loss in Desi chickpeas.
  • Ascochyta Blight can also affect seed quality resulting in lower grades. In chickpeas, Ascochyta Blight is much more aggressive than in lentils or peas and is caused by a different Ascochyta species.

RESOURCES

 

 

Seed Rot, Seedling Blight, Root Rot, Rhizoctonia Root Rot, Fusarium Root Rot, Aphanomyces Root Rot

CAUSED BY
  • These diseases are caused by a complex of pathogens including species of Pythium, Rhizoctonia, Botrytis, and Fusarium species.
  • These soil-borne fungi are seed or soil-borne and can infect the plant at any stage between germination and maturity, and any part of the root system up to a short distance above the soil surface.
  • These fungi are common in the soil, and infection is more likely if the soil around the seed is excessively wet. Warm and moist conditions generally favour these diseases, but cold and wet is also detrimental because the cool temperatures slow plant development and add additional stress.
  • Seed Rot and Seedling Blights are most severe when the soil is cool or saturated, and seedling emergence is delayed.

SYMPTOMS
  • Infected seed may fail to germinate. Infected seedlings will usually turn yellow, wilt, and then die. Stems may be girdled and discoloured at or just below the soil surface and roots may be rotten, allowing the plants to be pulled easily from the soil.
  • Kabuli chickpea is especially susceptible to rots due to its thin, zero-tannin seed coat.

PREVENTION AND CONTROL
  • Research has shown chickpeas to be partially resistant to Aphanomyces. If Aphanomyces has been confirmed in a field, chickpeas are a pulse option that can be used in rotation instead of peas or lentils, which are susceptible hosts.

IMPACT
  • This group of pathogens has the second highest impact in causing harm to chickpea yields and stunting of plants.

Botrytis Grey Mould

CAUSED BY
  • Caused by Botrytis cinerea Pers.ex Fr.
  • Grey Mould can be seed-borne, stubble-borne, air-borne and soil-borne and can attack at various stages of plant growth.
  • Infected seed produces infected seedlings, which die before emergence or soon after. On older plants, a greyish mould is observed, which quickly spreads under moist conditions.
  • This pathogen prefers cool temperatures, high humidity, wet soils, and dense canopies.

SYMPTOMS
  • On young plants that emerge, the grey mould appears as a grey mouldy growth visible at the soil surface. On older plants, it appears as a fuzzy grey or dirty white mouldy growth on flowers, pods, or lower areas of the stem.
  • The infected sites first develop small water-soaked lesions that expand to form large brown lesions with concentric zones. Under humid conditions, massive greyish-brown spores are produced to cover the infected tissues.
  • Sometimes, black sclerotia may be formed on old infected tissues. These lesions spread to the entire lower foliage. As the disease progresses, wilting, premature ripening, failure of pods to fill, and dead infected crop areas occur.

PREVENTION AND CONTROL
  • Treat seed or plant disease free seed.
  • Widen row spacing or lower seeding rates to improve air circulation in the crop.
  • No fungicides are registered for control in many of the pulse crops.
  • Potassium fertilizer in potassium deficient soils reduces the severity of Grey Mould.

Sclerotinia White Mould (Sclerotinia Rot)

CAUSED BY

Often called White Mould or Pod Rot, Sclerotinia Rot is caused by Sclerotinia sclerotiorum. The critical infection period is during the flowering stage. While White Mould is of minor importance in most pulse crops, it can cause severe losses in bean, where the infection can spread quickly. Sclerotinia overwinters in infected crop debris and soil.

This disease attacks chickpea grown in conditions of high rainfall, cool temperatures, and dense crop canopies. 

Sclerotinia White Mould is more common in crop rotations that include other susceptible broadleaf crops such as canola, mustard, lentils, or peas.   

SYMPTOMS

Symptoms usually occur in patches, typically in heavier crop areas.

Infected plants are initially paler green and the diseased tissue may be covered by a white, cottony, fungal growth.

The plant later becomes bleached in colour and the infected area will easily shred apart, revealing small black fungal resting structures called sclerotia bodies.

PREVENTION AND CONTROL

Bury all crop residues.

Avoid irrigating after the rows close over, and use wider row spacing and decreased seeding rates.

Fungicide use for control of Sclerotinia Stem Rot in the majority of pulse crops is not cost-effective because, once the canopy closes, the fungicides cannot reach their target.

Fungicides are available to control Sclerotinia.  However, they must be applied prior to the onset of symptoms.

IMPACT

Affected plants yield poorly and often die prematurely.

Sclerotinia becomes evident later in the growing season and if found, may have minimal impact on the crop. In most years it is not common through a lot of the chickpea growing area.

Resources

Related Links

Special thanks to Saskatchewan Pulse Growers.