Diseases of Papaya

a) Stem rot / Foot rot – Pythium aphanidermatum

• Water-soaked spot in the stem at the ground level which enlarge and griddle the stem. The diseased area turns brown or black and rot.
• Terminal leaves turn yellow droop off.
• The entire plant topples over and dies. Forward by rain. solani is favoured by dry and hit weather.
• Common in 2–3-year-old trees.
• Seed treatment with Thiram or Captan 4 g/kg or Chlorothalonil can control this disease.
• Drenching with Copper oxychloride 0.25 % or Bordeaux mixture 1% or Metalaxyl 0.1%.

b) Powdery mildew – Oidium caricae

• Seven attack causes yellowing and defoliation of leaves.
• The pathogen spread through wind borne conidia
• Spray Wettable Sulphur 0.25% or Dinocap 0.05% or Chinomethionate 0.1% or Tridemorph 0.1% to control the disease.

c) Papaya ring spot – Papaya ring spot virus

• Vein clearing, puckering and chlorophyll leaf tissues lobbing in. Margin and distal parts of leaves roll downward and inwards, mosaic mottling, dark green blisters, leaf distortion which result in shoe string system and stunting of plants.
• On fruits circular concentric rings are produced.
• Vectored by aphids Aphis gossypii, A. craccivora and also spreads to cucurbits not through seeds.

d) Leaf curl – Papaya leaf curl virus

• Curling, crinkling and distortion of leaves, reduction of leaf lamina, rolling of leaf margins inward and downward, thickening of veins.
• Leaves become leathery, brittle and distorted. Plants stunted. Affected plants does not produce flowers and fruits.
• Spread by whitefly Bemisia tabaci.
• Spraying with systemic insecticides to control the vector.

e) Anthracnose – Colletotrichum gloeosporioides

• It affects leaf and stem on erotic spots are produced.
• On fruit initially brown superficial discoloration of the skin develops which are circular and slightly sunken.
• Then they coalesce in which sparse mycelial growth appear on the margins of a spot.
• Under humid condition salmon pink spores are released. Fruits mummified and deformed.
• Infection is caused by fruit from field. Secondary spread by conidia by rain splashes
• Spray with Carbendazim 0.1% (or) Chlorothalonil 0.2% or Mancozeb 0.2% to control the disease.