Symptoms

• Water-soaked black lesions on leaves and stems
• Lesions expand rapidly and the entire leaf becomes necrotic.
• White sporulation (sporangia and sporangiophores) on leaves.

Fruit

• Dark brown lesions on fruit
• Soft rot and disintegration of fruits.

Symptoms on leaves	Fruit infection	Sporangiophores and sporangium	Oospore

Causal organism

• Phytophthora infestans (Mont.) de Bary

Asexual spores :

• Indeterminate sporangiophores, Zoospores: Biflagellate with one tinsel flagellum directed anteriorly and one whiplash flagellum directed posteriorly

Pathogen:

• Hyaline and coenocytic

Sexual spores :

• Thick-walled oospore

Survival and Mode of Spread

Survival :

• Infected Debris

Primary spread:

• Infected debris

Secondary spread:

• Wind

Favourable conditions :

• Cool nights, warm days and extended wet conditions from rain and fog
• Sporangia formed when RH is < 90%
• Optimum temp for sporulation is 18 - 22^oC

Integrated Disease Management:

• Proper drainage
• Crop rotation
• Soil application of Trichoderma asperellum (viride) @ 1.0 kg/ac
• Spray Cyazofamid 34.5% SC @ 80 ml/ac or Azoxystrobin 23% SC @ 200 ml/ac or Mancozeb 35% SC @ 1000 g/ac or Zineb 75% WP @ 800 g/ac or Azoxystrobin 18.2%+ Difenoconazole 11.4% SC @ 200 ml/ac

Source of Information

Acknowledgement