Diseases of fruit plantation medicinal and aromatic crops (2+1)

Powdery mildew

Causal organism: Erysiphe cichoracearum
Symptoms

• Small chloratic spots appear on the upper surface of leaves.
• The corresponding lower surface showing brownish discolouration prior to the appearance of powdery patches.
• Later appearance of white /grey colour powdery growth on both upper &lower surface of leaves It leads to heavy defoliation
TAXONOMY

Kingdom:Fungi
Division: Ascomycota
Class: Ascomycetes
Order: Erysiphales
Family: Erysiphaceae
Genus: Erysiphe

Species: cichoracearum

Etiology

• External septate mycelia, Haustoria sub epidermal. Septate mycelia produces conidiophore on which barrel shaped conidia are borne in chains
• Asexual spores : Barrel shaped conidia borne on Oidium.
• Sexual spores : Ascospores borne in Ascus. Asci are situated in Cleistothecium
• Asexual fruiting body: Oidium
• Sexual fruiting body: Cleistothecium.
• Primary Sources of Inoculum: Dormant mycelia and Short period cleistothecium.
• Secondary Sources of Inoculum: Air borne barrel shaped conidia.
Epidemiology

• Warm weather:
• Temp: 28-32°C.
• R.H: 85-86%.
• Cloudy weather.
• Susceptible Host
Life cycle of powdery mildew life cycle

• Affected plant parts having cliestothium as primary source of inoculum during favourable climate this will produce ascus in that ascospores are present because of lack of pressure inside the ascus they burst open and fly on to air and land on to the host, causes infection and causes powdery mildew of mint.
• In the affected host conidia are present , they produces oidium and cause infection by flight asexually.
• During adverse climatic conditions the fungi switched on to sexual reproduction where gametangial contact followed by plasmogamy, karyogamy, mitosis and meiosis takes place by this inoculum is reproduced .
Management

• Crop rotation with non host crops
• Altering the date of sowing
• Proper nutrient management.
• Avoid dense planting.
• Chemical :
• Prophylactic aerial spray- Wettable Sulphur 0.3% or Carbendazim 0.1% or Calyxin 0.15% at 10-15 days interval