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What is Anthracnose Disease and how to prevent your crops

Term ‘anthracnose’ is used to describe fungal diseases that cause symptoms like distortion, defoliation, blotching, leaf spot, shoot blight, dieback and twig cankers.

Causative Agent

Colletotrichum species, Diplocarpon (affecting roses), Elsinoe (affecting grapes)

List of Crops Affected by Anthracnose

  • Cotton
  • Cucurbits
  • Melons
  • Tomato
  • Mango
  • Onion
  • Chilli
  • Beans
  • Banana
  • Pepper
  • Passion Fruit
  • Cereals like rice, wheat
  • Honeydew
  • Citrus
  • Cashew
  • Avocado
  • Rockmelon

Symptoms

  • Lesions, sunken spots that are dark in color are the initial symptoms.
  • They often have a slightly raised rim.
  • The initial spores are pink colored and later they develop black-colored fruiting bodies.
  • Infection cannot be detected on green, immature fruits until they ripen since the fungus remains dormant on the unripe fruits.
  • If the fruits develop infection after harvest, it is because they were infected before harvest.
  • Pink colored spores develop en-mass on the leaves when weather is humid and they enlarge gradually to form dark brown margins.
  • The skin of the fruits shows large, circular, brown colored spots with puncture marks.

Spread of Disease

  • They spread mostly through water droplets.
  • Warm, humid conditions are favorable for the spread of the disease.
  • The disease also spreads through the previous crop debris if it is not properly disposed before the next plantation cycle.

Control of Disease (Conventional Farming)

  • The disease is controlled by spraying fungicides like mancozeb (2.5 grams per liter) or carbendazim (1.5 grams per liter).
  • The previous crop debris must be burnt and disposed properly.
  • While watering the plants care must be taken to dispense water only at the base of the plant or near the roots. Watering the leaves risk spread of the fungi.
  • Liquid copper spray and Sulphur powder can be used.

Control of Disease (Organic Farming)

  • Prune the diseased part of the plant.
  • Use disease free plant material.
  • Infected plants and plant parts must be destroyed immediately.
  • Disinfect the garden tools using bleach before and after use.
  • It is advisable to not walk around the field when it is wet.
  • Use neem oil spray right at the first symptom and use it every week after that.