Stem Gall of Coriander

Causal Organism: Protomyces macrospores
Sub-division: Ascomycotina

Symptoms:

• Galls Formation:
  • Galls appear on the leaves and stems of affected coriander plants.
  • Infected stems become swollen and distorted.
  • The shape of coriander seeds changes due to the disease.

Etiology:

• Primary Inoculum: Chlamydospores present in the soil or infected plant debris.
• Secondary Inoculum: Conidia spread through wind and rain splash.
• Favorable Conditions:
  • Variations in minimum and maximum atmospheric temperatures.
  • Relative humidity influences disease initiation and development.
  • Potassium and nitrogen fertilizers reduce stem gall incidence, while phosphorus fertilizers increase it.
  • Soil pH of 7.5 is most suitable for infection; lower pH levels show minimal infection.

Disease Cycle:

• Primary Infection: Occurs from chlamydospores present in infected plant debris or soil.
• Secondary Infection: Conidia spread by wind and rain cause new infections.
• The pathogen persists in the soil, leading to recurring infections in subsequent crops.

Management:

• Cultural Practices:
  • Use clean and healthy seeds.
  • Follow proper crop rotation to minimize inoculum buildup.
  • Early or late sowing reduces disease incidence:
    • Sowing around October 16 and November 16 minimizes yield losses.
• Seed Treatment: Treat seeds with Carboxin + Thiram @ 2g/kg of seeds.
• Foliar Sprays: Follow-up with foliar sprays of the same fungicides for effective disease management.
• Resistant Varieties: Use resistant cultivars such as JD 1, G-5365-91, Pant Haritma, UD 20, Rcr41, Pant1, and CIMAP-2053.