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Chickpea Diseases

Ascochyta

Description

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 is seed-borne, air-borne, spread by rain splash, and can survive on stubble for many years.

Causes

  • Cool temperatures
  • High humidity in the canopy
  • Rain-splashed spores
  • Air-borne spores

Symptoms

Symptoms of this chickpea disease appear as stem, pod, and leaf spots that are tan surrounded by a dark margin. Tiny black specks known as pycnidia occur in the centre of the spot. 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. 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.

Treatment & Prevention

  • Seed can be treated with various fungicides.
  • Post-emergent fungicides can be applied prior to flowering and can be repeated up to three times if conditions favour disease development.
  • Use disease-free, treated seed.
  • Bury all crop residues.
  • Avoid seeding next to the previous year’s pulse fields.

Grey Mold

Description

Caused by Botrytis cinerea Pers. ex Fr., Grey Mold can be seed-, stubble- , air- 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 mold is observed, which quickly spreads under moist conditions.

Causes

  • Cool temperatures
  • High humidity
  • Wet soils
  • Dense canopies

Symptoms

On young plants that emerge, the Grey Mold appears as a grey moldy growth visible at the soil surface. On older plants, it appears as a fuzzy grey or dirty white moldy 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.

Treatment & Prevention

  • 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 Mold.

White Mold

Description

Often called White Mold or pod rot, Sclerotinia rot is caused by Sclerotinia sclerotiorum. The critical infection period is during the flowering stage. While White Mold 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.

Causes

  • Cool temperatures
  • High humidity
  • Dense canopies
  • Growing pea and canola in the same rotation

Symptoms

The first sign of White Mold is the appearance of a light brown, water-soaked discolouration on the stem, leaves, or pods and a cottony threadlike growth in the collar region if the temperature and humidity levels remain high. A water-soaked area appears that spreads both upwards and downwards. Dark brown spots then develop on the stem, and the entire plant eventually turns brown. Affected plants often appear wilted and ripen prematurely due to rotting stems; lodging is common in affected areas. Stems, when split open, exhibit characteristic white fungus growth – numerous, black, hard resting bodies (sclerotia) may be present in the pith. Affected plants yield poorly and often die prematurely.

Treatment & Prevention

  • 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.