1. Stem rot or foot rot (Phytophthora spp., Phythium aphanidrmatum Rhizoctonia solani) : Water-soaked patches on the stem at ground level, which enlarge and girdle base of the developed stem. The affected tissues turn brown than black and rot. The terminal leaves turn yellow, wilt and drop. Fruits if formed also shrivel and drop off. The entire plant topples and dies because of the disintegration of parenchymatous tissue. For its management, Seed dressing with Captaf (Captan) or Chlorothalonil (Kavach) should be done before sowing the seeds. Soil at the orchard should be well drained. Before planting application of Neem cake + Trichoderma harzianum should be provided. Healthy nursery plants should be planted and crop rotation with non host crop should be followed. Soil drenching with tridemorph (Calixin 0.1%) or metalaxyl + mancozeb (Ridomil MZ 0.2%) or chlorothalonil (Kavach 0.2%) at bimonthly interval provide effective control for the standing crop.

2. Damping off (Pythium, Phytophthora, Rhictonia and Fusarium spp.)
Pre emergence damping off: Characterized as toppling of the growing tip before it comes out of the soil.
Post emergence damping off: Seedlings show pale withering and bending symptoms near the ground level with the severe girdling of the stem tissue. In case of Phytophthora and Fusarium, root rot is also observed. Such effected seedlings suddenly topple down.
Seeds for raising nursery should be obtained from healthy fruits. Water stagnation and low lying areas should be avoided for nursery. Seeds should be treated with oxycarboxin (Vitavax), carbendazim SD, captaf (Captan), Thiram @ 2 g/Kg seeds. Soil amendments with solarization, application of neem cake + Trichoderma harzianum, Dazomet, Formaldehyde should be practiced. Drenching of Nursery with chlorothalonil (Kavach 0.2%) or oxycarboxin (Vitavax 0.1%) or carbendazim (Bavistin 0.1%) should be done.

3. Anthracnose (Colletotrichum gloeosporioides (Penz.) Penz. & Sacc.)
Disease can attack fruits petioles, leaves, floral parts, etc. Water soaked spots first appear as brown superficial discoloration of the skin and then develop into circular, slightly sunken areas 1-3 cm diameter. Gradually the lesions coalesce and sparse mycelial growth often appears on the margins. Under humid conditions, encrustations of salmon pink spores often arranged in a concentric pattern develop on the surface of older spots. Fruits later turn dirty brown and rot. Infection at early stages results in mummification and deformation of fruits whereas at mature stage soft rot develops. Sometimes Chocolate colored unsunken lesions appear on the ripening fruits. The petioles of the lower leaves dry and shed off.
To control it, infected leaves should be removed and destroyed. Spraying of mancozeb (Dithane M 45 0.2%) or chlorothalonil (Kavach 0.2%) or carbendazim (Bavistin 0.1%) at 15 days interval provides effective control. Dipping fruits in water at 46 to 49°C for 20 minutes shortly after harvest provides control of disease under storage.

4. Powdery mildew (Oidium caricae (Noack.)
Small circular powdery patches develop on both the sides of leaves and on stem of young seedlings. These patches gradually extend, coalesce and cover the entire leaf surface. Badly infected leaves curl, dry, hang down and ultimately fall off. Young seedlings may die under severe disease attack. Sometimes in severe cases the pathogen attack fruits also. The disease is effectively controlled through the spraying of wettable sulphur (Sulfex 0.3%) when atmospheric temperature is below 30°C. Application of systemic fungicides namely tridemifon (Bayleton 0.1%) or carbendazim (Bavistin 0.1%) or thiophanate methyl (Topsin M or Roko 0.1%) at monthly interval is much more effective.

5. Ring spot virus (PSRV): Papaya ring spot disease is also known as papaya mosaic, papaya distortion mosaic, mild mosaic, papaya ring spot, papaya leaf reduction, thin leaf and distortion as all the above symptoms are caused due to Papaya ring spot virus. The typical mosaic caused by potex virus is so far not found in India.
PRSV-P strain naturally infects papaya and cucurbits. Plants of all ages are susceptible and symptoms are generally more severe during cooler weather. The disease derives its name from the characteristic dark green sunken rings that develop on fruit of affected plants. These rings often present as dark orange to brown markings as the fruit matures. Dark green, water-soaked streaks develop on petioles and stems. Mottle and mosaic patterns of varying severity develop on leaves that often have a ruffled appearance. One or more leaf lobes may become stunted and fruit set is markedly reduced or absent. Fruit from affected plants have poor flavour, a leathery appearance and are predisposed to fungal fruit rots. Growing of border crops viz., two rows of Sesbania or castor 15 days before planting of papaya, rouging and removal of early infected plants as and when noticed, helps to control the disease incidence. Several cultural practices have proven useful in slowing epidemics and reducing crop damage. Establishing plantations with seedling plants free of PRSV-P is essential, and new planting should be situated as far as possible away from affected plantations. Plantations can be surrounded by non host crops or interplant with other tree crops. Growing tolerant or resistant varieties is the best option. Genetically engineered resistance against PRSV has been achieved in Hawaii using Kapoho, Sunup and Rainbow cultivars. However, in India so far PRSV resistant cultivar is not been developed yet. Efforts are underway to develop PRSV resistant/tolerant types by crossing the commercially grown papaya varieties with wild species of Vasconcellea.