What are the common diseases of bitter melon?

ByMehedi Hasan Hours
common diseases of bitter melon

Bitter melon (Momordica charantia), also known as bitter gourd, is a popular vegetable in many Asian countries and is known for its various health benefits. However, like other crops, it is susceptible to several diseases that can significantly impact yield and quality. Understanding these diseases and their management is crucial for successful cultivation.

1. Powdery Mildew (Sphaerotheca fuliginea)

Symptoms:

  • Favored by high humidity and initially affects older leaves.
  • Appears as white powdery residue primarily on the upper leaf surface.
  • Circular patches or spots on the lower leaf surface.
  • In severe cases, both surfaces of leaves, petioles, and stems are covered.
  • Leaves turn brown, shrivel, and may fall off.
  • Fruits remain small and underdeveloped.

Control:

  • Spray Carbendazim (1 ml/litre of water) or Karathane (0.5 ml/litre of water) immediately after the disease appears.
  • Repeat 2-3 sprays at 15-day intervals.

2. Fusarium Wilt (Fusarium oxysporum f. sp. niveum)

Symptoms:

  • Initial temporary wilting, which becomes permanent and progressive.
  • Leaves show yellowing, loss of turgidity, and drooping symptoms.
  • Plants eventually die, though roots remain unaffected.
  • Older plants exhibit sudden leaf wilting and yellow or brown vascular bundles in the collar region.

Control:

  • Apply three sprays of Karathane (6 g in 10 litres of water) or Bavistin (1 g/litre of water) at 5-6 day intervals.
  • Ensure thorough drenching of leaves during spraying.

3. Downy Mildew (Pseudoperonospora cubensis)

Symptoms:

  • Common in high-humidity areas, especially with regular summer rains.
  • Yellow angular spots appear on the upper leaf surface.
  • Under high humidity, a whitish powdery growth is seen on the lower leaf surface.
  • Rapid spread leads to quick defoliation and plant death.

Control:

  • Use Ridomil (1.5 g/litre of water) and a protectant fungicide like Mancozeb (0.2%) to prevent resistant strains.

4. Bitter Gourd Mosaic

Symptoms:

  • Virus disease mainly affects leaves.
  • Irregular yellowish patches on the leaves of secondary branches.
  • Vein clearing in one or two leaf lobes; severe cases show reduced leaf size and malformed development.
  • Young leaves appear distorted and malformed.
  • Aphids spread the virus.

Control:

  • Spray Monocrotophos (0.05%) or Phosphamidon (0.05%) at 10-day intervals post-germination to prevent aphid vectors.

5. Bitter Gourd Witches’ Broom

Symptoms:

  • Infected plants do not bear fruit if infected early, leading to 100% loss.
  • Proliferation and malformation of axillary buds.
  • Abnormally small leaves, increased flower production, and early blossoming.
  • Infected flowers show green, phyllody symptoms.
  • Fruits are small, cylindrical, deformed, smooth, and seedless.

Control:

  • Apply Carbofuran (1.5 kg a.i./ha) during seed sowing.
  • Follow up with 5-6 foliar sprays of Phosphamidon (0.05%), Monocrotophos (0.05%), or Oxydematon Methyl (0.05%) at 10-day intervals to control vectors.
  • Weekly sprays of Oxytetracycline hydrochloride solution (500 ppm) can suppress disease symptoms.