Vector: Aphids

Viral Disease

Vector: Aphids

Viral Disease

Cucumber Mosaic Virus (CMV) in Bananas – Symptoms, Transmission, and Management

Introduction

Cucumber Mosaic Virus (CMV) is a serious viral disease affecting banana plants, leading to stunted growth, distorted leaves, and reduced fruit quality. The virus has a broad host range and can infect over 800 plant species, making its control challenging.

1. Symptoms of CMV in Bananas

• Leaf Symptoms:

  • Black or purple lines with necrosis on older leaves
  • Leaf distortion and stunted growth

• Fruit Symptoms:

  • Chlorotic lines or necrosis on banana fruits
  • Smaller and deformed fruits
  • Infected plants may fail to mature or produce bunches

2. Transmission of CMV

• Aphid Vectors:

  • CMV is transmitted in a non-persistent manner by at least 75 aphid species.
  • Pentalonia nigronervosa (banana aphid) is not a major vector, but other aphids can spread the virus rapidly.

• Infected Planting Material:

  • Root suckers and tissue-cultured plantlets from infected mother plants can spread CMV.

• Weather Conditions:

  • Frequent rainfall and specific weather conditions increase the risk of virus transmission.

• Alternative Hosts:

  • Weeds like Commelina diffusa and intercropped vegetables (e.g., cucumbers, tomatoes, peppers) act as reservoirs for the virus.

3. CMV Management Strategies

• Use Virus-Free Planting Material:

  • Tissue-cultured plantlets and suckers should be sourced from virus-free mother plants.
  • Heat treatment and apical meristem culture can eliminate CMV from infected plants.

• Field Sanitation:

  • Remove infected banana plants to prevent further spread.
  • Eliminate alternative host plants (weeds and susceptible vegetable crops) around banana fields.

• Planting Strategies:

  • Avoid intercropping bananas with susceptible vegetables.
  • Growing bananas next to non-host crops like rice reduces virus incidence.

• Aphid Control:

  • Insecticides are not highly effective as aphids transmit CMV within seconds of feeding.
  • However, a combination of roguing infected plants and insecticide use may help in commercial plantations.

4. CMV and Banana Mosaic Disease

• CMV belongs to the genus Cucumovirus (Family Bromoviridae).
• It has a tripartite RNA genome enclosed in isometric virions (28–30 nm in diameter).
• CMV isolates are classified into Subgroups I and II, with Subgroup I being more common in tropical regions.

Conclusion

Since CMV spreads quickly through aphids and infected planting material, preventive measures such as using virus-free plants, removing infected plants, and managing alternative hosts are crucial for controlling the disease in banana plantations. 

Source: Diseases of Banana and PlantainRandy C. Ploetz 1, John E. Thomas 2 and Walter R. Slabaugh 31University of Florida, Tropical Research and Education Center, Homestead,Florida, USA; 2Queensland Department of Primary Industries, QueenslandHorticulture Institute, Indooroopilly, Queensland, Australia; 3Agraquest Inc.,1050 Echo Avenue, Parma, Idaho, USA