Phyllosticta zingiberi

Fungal Disease

Phyllosticta zingiberi

Fungal Disease

Introduction

Leaf spot disease of ginger, caused by Phyllosticta zingiberi, is a serious fungal disease affecting ginger crops, leading to significant yield losses. The disease is prevalent during wet weather conditions, particularly from July to October.

Symptoms

• The disease starts as water-soaked spots on leaves.
• Spots develop into white lesions with dark brown margins and a yellow halo.
• The lesions enlarge, and adjacent spots merge to form necrotic areas.
• In severe cases, the infection leads to leaf blight, causing leaves to dry up.
• Reduction in photosynthetic area results in 13% to 66% yield loss due to a decrease in rhizome size and number.

Disease Spread and Favorable Conditions

• The pathogen spreads through rain splashes during intermittent showers.
• The disease is more severe in exposed conditions where ginger is grown without shade.
• Heavy rainfall and temperatures between 22-28°C during July-August favor disease development.
• Increased relative humidity and leaf wetness are crucial for the rapid spread of the disease.
• Studies indicate that 85.48% of disease severity is influenced by air temperature, humidity, and cumulative rainfall.

Management Strategies

• Cultural Practices:

  • Ensure proper spacing and good air circulation to reduce humidity around plants.
  • Avoid planting in low-lying areas where waterlogging occurs.
  • Remove and destroy infected leaves to prevent the spread.

• Chemical Control:

  • Spraying Mancozeb (0.25%) or Copper oxychloride (0.3%) at the first appearance of symptoms can help control the disease.
  • A second spray may be required after 10-15 days if weather conditions remain favorable.

• Biological Control:

  • Application of Trichoderma-based biocontrol agents can help in reducing disease incidence.
  • Use of neem-based formulations may also provide some protection.

Conclusion

Leaf spot disease is a major threat to ginger cultivation, particularly in high-humidity regions. Timely identification, proper field management, and appropriate chemical or biological treatments can help minimize yield losses and ensure a healthy crop.