Diseases


Disease Pathogen Pathogenic part
Anthracnose and chocolate spot Colletotrichum gloeosporioides fruits, petioles
Phytophthora Phytophthora palmivora fruit, stem, roots
Powdery mildew Oidium caricae leaves
Black spot Cercospora papayae fruit
Damping off Pythium, Phytophthora, Rhizoctonia seedlings
Wet rot Phomopsis sp. fruit
Dry rot Mycosphaerella sp. fruit
Watery fruit rot Rhizopus stolonifer /
Stem-end rot Botryodiplodia theobromae, Rhizopus stolonifer, Phomopsis sp. , Mycosphaerella sp. mature fruit
nematode disease Reniform nematodes, Rotylenchulus reniformis,Root-knot nematodes, Meloidogyne spp. root

Papaya ringspot virus(PRSV)


Papaya ringspot virus (PRSV) is an aphid-transmitted plant virus belonging to the genus Potyvirus, family Potyviridae, with a positive sense RNA genome.There are two main types of this virus that are serologically indistinguishable and are so closely genetically related that they are now considered the same virus species. Type P isolates (PRSV-P) infects papaya and several members of the melon family (Cucurbitaceae). The other type, Type W isolates (PRSV-W) infects only cucurbits such as watermelon, cucumber, and squash and were originally known as Watermelon mosaic virus (Tripathi et al. 2008).

Distribution

Both pathotypes are distributed worldwide. PRSV-P is found in places where papaya mainly grow (Tripathi et al. 2008).

Physical property

Virions are filamentous, non-enveloped and flexuous with the length of 760-800nm and the width of 12 nm. Virus particles comprise of 94.5% protein, containing the virus coat protein (CP) with a molecular weight of about 36kDa and 5.5% nucleic acid (Tripathi et al. 2008).

Transmission

The virus is usually transmitted through aphids in a non-persistent way. But the virus can also be not seed-transmitted (Tripathi et al. 2008).

Hosts

PRSV has a limited number of hosts which belong to the families Caricaceae, Chenopodiaceae and Cucurbitaceae. Propagation hosts are: Carica papaya, Cucurbita pepo and Cucumis metuliferus cv. accession 2459. Local lesion assay hosts are: Chenopodium quinoa and Chenopodium amaranticolor (Tripathi et al. 2008).

Control

Two transgenic papaya varieties, Rainbow and SunUp, with engineered resistance to PRSV have been commercially planted in Hawaii since 1998. A lot of practices have implanted to manage the disease like transgenic resistance, tolerant cultivar, cross-protection and so on (Tripathi et al. 2008).


Insects


Common name Scientific name
Stevens leafhopper Empoasca stevensi
Mediterranean fruit fly Ceratitis capitata
Melon fly Bactrocera cucurbitae
Oriental fruit fly Bactrocera dorsalis

Mites


Common Name Scientific name Pathogenic part
Broad mite Polyphagotarsonemus latus seedlings, young plants, lower surface of young leaves
Red and black flat mite Brevipalpus phoenicis fruit
Tuckerellid mites Tuckerella ornata, T. pavoniformis trunks of old plants
Carmine spider mite Tetranychus cinnabarinus lower surface of mature leaves
Citrus red mite Panonychus citri upper surface of mature leaves
Texas citrus mite Eutetranychus banksi upper surface of mature leaves