Papaya Diseases A

Lecture To ToT trainees ( FFS)

By Mr. Allah Dad Khan

Provincial Coordinator IPM KPK

MINFAL Pakistan

Anthracnose Colletotrichum gleosporoides

Symptoms Anthracnose lesions on papaya fruit

Small water-soaked lesions of fruit during ripening; circular sunken lesions with light brown margins

Cause Fungus Comments Fungi spread by wind and rain;

disease emergence favored by high temperature and humidity; disease can have a serious impact on refrigerated fruit for export

Management Appropriate protective fungicides

should be applied; dipping fruits in hot water at 48°C for 20 minutes reduces the incidence of the disease

Anthracnose

Anthracnose lesions on papaya fruit

Anthracnose lesions on papaya fruit

Anthracnose

Anthracnose symptoms on papaya

Anthracnose lesions on papaya fruit

Anthracnose

Anthracnose lesions on papaya fruit

Anthracnose lesions on papaya fruit

Black spot Asperisporium caricae

Symptoms Symptoms of black spot on papaya fruit

Circular water-soaked or brown lesions on older leaves; centers of lesions become bleached as they mature; leaves curling and turning brown; raised lesions on trunks; sunken circular lesions on fruit

Cause Fungus Comments Disease spread by wind and rain;

disease emergence favored by cool weather interspersed with moisture from dew or rain

Management Disease may require applications of

appropriate fungicides for adequate control

Black Spot

Symptoms of black spot on papaya leaf

Symptoms of black spot on papaya leaf

Black Rot

Symptoms Black rot symptoms Black sunken rot on young fruits

originating from stem end or contact with a leaf; young fruit withering and dropping from plant; small, brown sunken lesions with light brown margins on ripening fruit

Cause Fungus Comments Fungi enters fruit through wounds Management Appropriate protective fungicides

should be applied; dipping fruits in hot water at 48°C for 20 minutes reduces the incidence of the disease

Phytophthora fruit rot (Stem rot) Phytophthora palmivora

Symptom Symptoms of Phytophthora infection on papaya fruits

s Water-soaked lesions on unripe fruit that

oozes latex; withering fruit; water-soaked lesions on leaf scars of fruit bearing stem; mature fruit covered in white mycelium

Cause Oomycete Comments Fungi survive in soil and enter through

wounds in stem; disease often emerges after hurricane damage

Management Disease can be controlled through the use of

appropriate protective fungicides such as mancozeb or copper sulfate; root rot in seedlings can be prevented by planting in holes filled with soil in which papaya has never been grown - by the time the roots extend out of the added soil the plant is no longer susceptible to the disease

Phytophthora

Symptoms of Phytophthora infection on papaya fruit

Symptoms of Phytophthora infection on papaya fruit

Phytophthora

Symptoms of Phytophthora infection on papaya fruit

Phytophthora on papaya fruit (after experimental inoculation with pathogen)

Bacterial canker and decline Erwinia spp.

Symptom s Angular water-soaked lesions on

leaves; lesions coalesce and spread along leaf veins; witling leaves, particularly at top of canopy; water-soaked lesion and cankers on stem; cankers girdle stem and cause plant to collapse; small water-soaked lesions on green fruit

Cause Bacteria Comments Bacteria survive in lesions and

cankers

Bunchy top Likely caused by Rickettsia bacteria

SymptomsChlorosis of young leaves; water-soaked spots on

petioles and stems; petioles rigid, horizontal and shortened; thickened leaf blades that cup downward; internodes shorten and growth stops resulting in a bunchy appearance to the plants

CauseBacteriaCommentsTransmitted by leaf hoppersManagementUse of tolerant varieties of papaya is currently the

only method of control 

Cercospora black spot Cercospora papayae

Symptoms Symptoms of Cercospora black spot on papaya

Tiny black dots on fruit which enlarge to 3 mm across; spots are slightly raised and although indistinct on unripe green fruit, become visible on ripening to yellow; lesions on leaves are irregular in shape and gray-white in color; if infestation is severe, leaves may turn yellow and necrotic and drop from plant

Cause Fungus Comments Disease usually enters orchard from

infected papaya leaves in adjacent orchards

Management Applications of appropriate protective

fungicides at intervals of 14 to 28 days provide satisfactory control of the disease

Papaya ringspot Papaya ringspot virus (PRV)

Symptoms Papaya ringspot symptoms on fruit

Dark green rings on fruit which may be slightly sunken and become less distinct as the fruit ripens; fruits may have uneven bumps; leaves often exhibit a bright yellow mosaic pattern and new leaves are small and plant growth is stunted

Cause Virus Comments Virus is transmitted by several aphid species Management Infected plants should be removed and

destroyed to prevent spread of the virus; new planting materials should be free of the virus; intercropping papaya with a non-host such as corn can help to reduce the incidence of the disease in papaya orchards by providing aphid vectors with an alternative feeding site

Papaya ringspot

Papaya ringspot symptoms on unripe fruit

Papaya ringspot symptoms on unripe fruit

Papaya ringspot

Foliar symptoms of papaya ringspot

Papaya ringspot symptoms on fruit

Papaya ring spot

Foliar symptoms of papaya ringspot

Foliar symptoms of papaya ringspot

Papaya ringspot

Papaya ringspot symptoms on fruit

Papaya ringspot symptoms on unripe fruit