Ppt on Major Diseases Of Papaya And Their Management Strategies

This presentation covers the major diseases of papaya, including their causal organisms, symptoms, disease cycles, and management strategies. Emphasis is placed on fungal, viral, and post-harvest diseases, with integrated management approaches. Key concepts include pathogen identification, symptomatology, disease management, and post-harvest handling. Important academic keywords: pathogen, symptoms, management, fungal diseases, viral diseases.
Introduction to Papaya Diseases
  • Papaya is susceptible to various fungal, viral, and post-harvest diseases.
  • Diseases affect yield, fruit quality, and marketability.
  • Effective management requires accurate diagnosis and integrated approaches.
Major Fungal Diseases of Papaya
  • Powdery Mildew: Oidium indicum, Oidium caricae, Leveillula taurica
  • Leaf Blight: Corynespora cassiicola
  • Damping-Off: Pythium aphanidermatum, Rhizoctonia solani
  • Foot Rot: Pythium aphanidermatum
  • Anthracnose: Colletotrichum gloeosporioides
Powdery Mildew
Pathogen: Oidium indicum, Oidium caricae, Leveillula taurica
Nature: Obligate parasite, hyaline ectophytic mycelium, conidia in chains.
Symptoms:
  • Speckled, water-soaked spots on leaf underside.
  • Powdery patches enlarge, covering leaves.
  • Leaves become chlorotic, distorted, and fall prematurely.
Management:
  • Clean cultivation and balanced fertilization (increase K, reduce N).
  • Dusting sulfur (30 g/10 L water) at symptom onset.
  • Spray Triadimefon (0.1%) or systemic fungicides (Bayleton, carbendazim) at intervals.
Foot Rot / Stem Rot
Pathogen: Pythium aphanidermatum
Nature: Sporangia produce zoospores; oospores are thick-walled sexual spores.
Symptoms:
  • Water-soaked patches at stem base, girdling stem.
  • Tissues turn brown/black and rot; terminal leaves yellow and wilt.
  • Fruits shrivel and drop; plant may topple and die.
  • Roots deteriorate; bark appears dry, honeycomb-like.
Management:
  • Use well-drained nursery beds; remove and destroy diseased seedlings.
  • Apply Trichoderma viride (15 g/plant) with FYM at planting.
  • Seed treatment with captan (4 g/kg) or chlorothalonil (2 g/kg).
  • Drench stem base with COC (0.25%), metalaxyl (0.1%), or Bordeaux mixture (1.2%).
Anthracnose
Pathogen: Colletotrichum gloeosporioides
Nature: Ascomycete fungus; produces conidia and ascospores.
Symptoms:
  • Gray to brown spots with dark margins and yellow halo on leaves.
  • Necrotic areas form as spots coalesce.
  • Fruits develop light spots that enlarge, become dark brown, and may show concentric rings.
  • Premature fruit drop common.
Management:
  • Remove and destroy affected fruits.
  • Harvest fruits at maturity.
  • Spray copper oxychloride (0.3%), carbendazim (0.1%), or thiophanate-methyl (0.1%) every 15 days.
  • Hot water or fungicidal wax treatment for export fruits.
Major Viral Diseases of Papaya
  • Papaya Mosaic Virus (transmitted by Aphis gossypii)
  • Papaya Leaf Curl Virus (transmitted by Bemisia tabaci)
  • Papaya Ring Spot Virus (PRSV; transmitted by aphids)
Papaya Mosaic Virus
Pathogen: Papaya mosaic virus
Transmission: By aphid (Aphis gossypii)
Symptoms:
  • Mild mosaic pattern and deformation in young leaves.
  • Dark green blister-like patches on yellowish-green leaves.
  • Leaf vein clearing, downward curling, and shortened petioles.
Papaya Leaf Curl Virus
Pathogen: Papaya leaf curl virus
Transmission: By whitefly (Bemisia tabaci)
Symptoms:
  • Severe curling, crinkling, and deformation of young leaves.
  • Vein clearing and thickening; twisted petioles.
  • Stunted growth, reduced yield, and possible defoliation.
Papaya Ring Spot Virus (PRSV)
Pathogen: Papaya ring spot virus
Transmission: By aphids (non-persistent manner)
Symptoms:
  • Prominent mosaic and chlorosis on leaves.
  • Oily streaks on petioles and trunk.
  • Distorted young leaves; concentric rings and C-shaped markings on fruits.
Viral Disease Management
  • Use disease-free seedlings for planting.
  • Rogue and destroy infected plants promptly.
  • Control vectors with insecticides (monocrotophos 0.05%, dimethoate 0.2%, metasystox 0.1%).
Post-Harvest Diseases of Papaya
  • Macrophomina Rot: Macrophomina phaseolina
  • Rhizopus Rot (Soft Rot): Rhizopus stolonifer
  • Phomopsis Rot: Phomopsis caricae
  • Anthracnose: Colletotrichum gloeosporioides
Macrophomina Rot
Pathogen: Macrophomina phaseolina
Symptoms:
  • Small water-soaked spots on fruit surface.
  • Spots deepen, causing internal rot and sclerotia formation.
  • Inner tissues turn brownish-black with dark mycelial growth.
Rhizopus Rot (Soft Rot)
Pathogen: Rhizopus stolonifer
Symptoms:
  • Irregular water-soaked lesions on injured fruits.
  • Lesions covered with whitish fungal growth, turning dark brown.
  • Fruit becomes watery, emits foul odor, and infection spreads rapidly.
Phomopsis Rot
Pathogen: Phomopsis caricae
Symptoms:
  • Initial water-soaked spots become sunken and dark brown to black.
  • Spots may be surrounded by white, raised tissue.
  • Infected area becomes soft and pulpy.
Post-Harvest Disease Management
  • Harvest fruits at proper maturity and during cool hours.
  • Dipping fruits in TBZ (1000 ppm) or benomyl (20 ppm) reduces storage decay.
  • Dusting fruits with benzoic acid (0.1%) in kaolin reduces rotting.
Summary: Integrated Disease Management in Papaya
  • Adopt clean cultivation and use disease-free planting material.
  • Monitor and manage vectors for viral diseases.
  • Apply recommended fungicides and biological agents for fungal diseases.
  • Practice proper post-harvest handling to minimize losses.