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White spots on papaya

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Powdery Mildew of Papaya

In a Nutshell

  • Speckled water soaked spots on leaf underside.
  • Later become powdery patches.
  • Spots enlarge, covering leaf.
  • Chlorotic and distorted leaves.
  • Premature leaf fall.

Symptoms

Water-soaked spots covered with whitish powdery fungal mats appear first on the underside of leaves, often adjacent to the leaf veins, on leaf petioles and and at the base of flowers. Occasionally, pale green to yellow spots arise on the upper side of the leaves, sometimes covered with white mold. These spots may turn necrotic brown and be surrounded by a yellow halo later. Heavily infected leaves later whither and curl inwards. The fruits might show mats of whitish mold of variable sizes. The infection generally causes little damage to old bearing trees. However, in young plants it can lead to the death of growing tissues, defoliation, stem and fruit lesions and important yield losses.

Hosts

Trigger

The disease is caused by the fungus Oidium caricae-papayae. The fungus survives and reproduces on papaya plants only. The spores are dispersed from plant to plant and between fields by wind. Leaves at all growth stages can be affected, but older leaves are more susceptible. The fungus colonizes the epidermal plant cells, which is what causes the symptoms. The development of the disease and the severity of the symptoms are promoted by low light levels, a high degree of humidity, moderate temperatures (18 to 32В°C), and rainfall ranging from 1500 to 2500 mm per year.

Biological Control

Wettable sulfur, sulfur dust, or lime sulfur as well as potassium bicarbonate have proved helpful in controlling this disease. However, these treatments can be toxic to the plants if applied during hot weather. In some cases, baking powder, neem oil extracts and soap solutions can be useful. In all cases, these treatments are not very effective if the disease is severe.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatments if available. Fungicides such as azoxystrobin, mancozeb can be applied to control powdery mildew on papaya.

Speckled water soaked spots on leaf underside. Later become powdery patches. Spots enlarge, covering leaf. Chlorotic and distorted leaves. Premature leaf fall. Hosts Papaya.

Papaya Disease & White Growth Anomaly Photographs
Photos of stringy sinuous white growth in the fruit of the Papaya (pawpaw) (Carica papaya L.)

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Photographs of white sinuous or filamentous growth through the fruit or ovary of a papaya:

What is the probable cause and what may be the significance of the white growths throughout the fruit of this papaya? Is this a plant disease, a fungus, or a genetic anomaly? Is this papaya safe to eat?

Included in this article series are photographs of plants and matching pollen from other areas in the U.S., Canada, Spain, France, and Mexico, and from other countries. Included are pollen and plants include the New York Hudson Valley. We include links to detailed articles about individual pollen and plant species.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Papaya (Carica papaya L.) White Growth or “Disease” Photographs

[Click to enlarge any image]

Shown here are photographs of a white fibrous growth throughout the normally-edible portion of the fruit of a papaya plant.

We have asked for opinions from experts on the papaya plant to address the following six questions. Readers and papaya experts are invited to CONTACT US with comments or suggestions.

  1. What is this white growth?
  2. Is it fungal, is it a plant disease, or is it a genetic disorder or aberration?

Above we see fairly typical papaya seeds in the center of this fruit, and in our second photo we see rather obvious indication that the white fibrous growth that permeates the normally pure orange fruit of the papaya ovary wall is emanating from the white liner or lactifer (latex ducts) to which seeds are attached and from which they are formed.

  1. What are the causes of this papaya “disease”?
  2. Is this papaya safe to eat?
  3. Are there external symptoms on a papaya fruit that might indicate the presence of this papaya disorder?
  4. Is there something else we should ask about this papaya and its edibiltiy?

Other observations about this specific papaya shown above included a sticky surface on the fruit’s exterior and a bit of (rather typical) mould growing at the fruit’s base.

I could but did not bother to identify this fungus as it is entirely common on other papayas in the marketplace and from its location and compared with the internal growths we document above, I did not see an obvious connection between the fungus and the problem under discussion.

Typically I find species of Aspergillus sp. or sometimes Penicillium sp. in these white mould deposits and on occasion one finds one of the mildews present. For example

And under the microscope we see the fibrous growth and no obvious fungal material in the papaya flesh.

Note: reviewing lists of diseases of papaya we did not find a description that included white streaks or striations within the fruit of the papaya itself.

The only papaya disease involving the term “streaks” was of “streaks of an oily appearance” along the main stem of papaya plants describe by Hine, Gonsalves and others, in discussion of payaya ringspot disease a viral infection that does not appear related to the white streaks or striations shown on this page. (Hine 1965)

The first symptoms are the appearance of oily streaks on the younger leaves and the younger leaves show clearing along the veins that gives an appearance of flecks.

These early symptoms are used to detect infected plants when rogueing is used for managing the disease. – (Gonsalves 2010)

White Fibrous Papaya Growth / Streaks / Veins: Diagnosis & Comments

Thanks for your query regarding the flesh disorder of papaya which was forwarded to our pathology group in North Queensland, Australia.

The group has seen and is not aware of similar symptoms occurring in Australian produced fruit.

After looking at all the images we agree with Daniel that the disorder is not related to any disease.

It appears that something has affected the laticifers (latex ducts) or the vascular material resulting in an aberration of the tissue.

It is difficult to determine the actual cause without having knowledge of the growing conditions, variety, field and postharvest treatments, incidence and severity (eg. one fruit on one plant).

One way to determine if it is specifically the laticifers that are affected would be touch the surface of freshly cut fruit and feel if it is sticky. – Kathy Grice, Senior Experimentalist, Horticulture and Forestry Science, Department of Agriculture and Fisheries, Mareeba, Queensland Australia [by private email] 2016/06/22

List of Diseases of the Papaya Plant & Fruit

List of Common Diseases of Papaya

Ilustrations above and below: Hawaiian payaya infected with Phytophtora parasitica, a fungal disease, discussed by Hine et als in Diseases of Papaya, cited below. The first photo is of Phytophtora parasitica on papaya in the field and the second is a payaya infected with Phytophtora parasitica after having been inoculated in the lab.

[Click to enlarge any image]

We include these payaya fungal infection photos to help distinguish between the white streaky striations found in the papaya fruit discussed above on this page from common payaya diseases.

Various authors including Hine cite the predominant diseases infecting papaya (Carica payaya L.) to include the following conditions. These are discussed by the authors cited below, beginning with Hine (1965).

Non-Parasitic Diseases of Papayas

  • Over-watering or water-saturated soil exposure for 24-hours or more
  • Nutritional diseases such as nitrogen deficiency
  • Defective plants, females, lacking stamens, don’t produce fruit

Parasitic Diseases of Papayas

Virus Diseases of Payaya
  • Papaya Mosaic
  • Papaya Ringspot
Fungus Diseases of Payaya
  • Anthracnose
  • Black Spot of Papaya
  • Damping-off of Seedlings
  • Dry Rot and Stem-end Rot
  • Internal Blight
  • Phytophthora Blight – shown in the photo (Hines 1965)
  • Powdery Mildew .
  • Replant Problem
  • Rhizopus Fruit Rot
Nematode Diseases of Papaya
  • Root-knot Nematode
  • Reniform Nematode
Papaya Diseases of Unknown Cause
  • Freckles
  • Lumpy Fruit

Research References on Payaya Diseases

Illustration: a photograph of healthy flesh and seeds of a payaya – Plantvillage (2020) cited in detail below.

    Abreu, Paolla, Tathiana FS Antunes, Anuar MagaГ±a-ГЃlvarez, Daisy PГ©rez-Brito, RaГєl Tapia-Tussell, JosГ© A. Ventura, Antonio AR Fernandes, and Patricia Fernandes. A current overview of the PAPAYA MELEIRA VIRUS, an unusual plant virus [PDF] Viruses 7, no. 4 (2015): 1853-1870. Retrieved 2020/05/20 original source: https://biblioteca.incaper.es.gov.br/digital/bitstream/item/748/1/CurrentOverviewofthePapayameleiravirusVentura.pdf
    Abstract excerpt:

Papaya meleira virus (PMeV) is the causal agent of papaya sticky disease, which is characterized by a spontaneous exudation of fluid and aqueous latex from the papaya fruit and leaves. T

The latex oxidizes after atmospheric exposure, resulting in a sticky feature on the fruit from which the name of the disease originates.

Note: This article offers an additional 71 research citations on diseases of papaya – Ed.

  • Andersen, M. T., J. Longmore, L. W. Liefting, G. A. Wood, P. W. Sutherland, D. L. Beck, and R. L. S. Forster. “Phormium yellow leaf phytoplasma is associated with strawberry lethal yellows disease in New Zealand.” Plant Disease 82, no. 6 (1998): 606-609.
  • Ayoola, P. B., and A. Adeyeye. “Phytochemical and nutrient evaluation of Carica papaya (pawpaw) leaves.” IJRRAS 5, no. 3 (2010): 325-328.
  • Chukwuka, K. S., I. O. Okonko, and A. A. Adekunle. “Microbial ecology of organisms causing pawpaw (Carica papaya L.) fruit decay in Oyo State, Nigeria.” American-Eurasian Journal of Toxicological Sciences 2, no. 1 (2010): 43-50.
  • Crane, J. H. Papaya growing in the Florida home landscape. University of Florida IFAS Extension. https://edis.ifas.ufl.edu/pdffiles/MG/MG05400.pdf
  • Da Silva, JA Teixeira, Zinia Rashid, Duong Tan Nhut, Dharini Sivakumar, Abed Gera, Manoel Teixeira Souza Jr, and Paula F. Tennant. “Papaya (Carica papaya L.) biology and biotechnology.” Tree and Forestry Science and Biotechnology 1, no. 1 (2007): 47-73.
  • Firrao, G., K. Gibb, and C. Streten. “Short taxonomic guide to the genus’Candidatus Phytoplasma’.” Journal of Plant pathology (2005): 249-263.Maktar, N. H., S. Kamis, F. Z. Mohd Yusof, and N. H. Hussain. “Erwinia papayae causing papaya dieback in Malaysia.” Plant Pathology 57, no. 4 (2008): 774-774.
  • Hine, R.B., O.V. Holtmann, R.D. Raabe, DISEASES of PAPAYA [PDF], University of Hawaii, Hawaii Agricultura Experiment Station, Bulletin 136 (JUly 1965), retrieved 2020/05/20 original source: https://www.ctahr.hawaii.edu/oc/freepubs/pdf/B-136.pdf
  • Gonsalves, Dennis, Savarni Tripathi, James B. Carr, and Jon Y. Suzuki. PAPAYA RINGSPOT VIRUS [PDF] The Plant Health Instructor 10 (2010): 1094. retrieved 2020/05/20 original source: http://sipco.ica.gov.co:8080/bitstream/123456789/17511/2/Gonsalves_etal_2010.pdf

    Abstract excerpt:
    The term papaya ringspot (PRS) was first coined by Jensen in 1949 to describe a papaya disease in Hawaii.

    Previously described diseases such as papaya mosaic (caused by Papaya mosaic virus) and watermelon mosaic (caused by Watermelon mosaic virusВ­1) were shown recently to be caused by Papaya ringspot virus (PRSV).

    The virus (PRSV) causes a major disease of papaya and cucurbits and is found in all areas of the world where papaya and cucurbits are cultivated.

  • Kumar, Vinod, PAPAYA DISEASES & . CONTROL [PDF] Agropedia, retrieved 2020/05/20 original source: http://agropedia.iitk.ac.in/content/papaya-diseases-its-control
  • Macalood, J. S., H. J. Vicente, J. G. Gorospe, R. D. Boniao, and E. C. Roa. “Revisiting Carica papaya L. latex potentials may resolve agricultural infestation problems.” International Journal of Scientific & Technology Research 3, no. 1 (2014): 95-8.
    Abstract:

    Infestation problems are among the top concerns of many farmers worldwide. The use of synthetic pesticides as one of the pest control methods had been employed which caused many negative impacts both in the environment and human health.

    Effectivity of synthetic pesticides is only short-term which cannot compel for its undesirable impacts. Researches investigating plant potentials as an alternate pesticide for pest control were suggested as a promising solution without sacrificing the environment and its components.

    Carica papaya L. latex is known to contain a lot of phytochemicals including papain, a cysteine proteinase thought to effectively involved in plant defense against herviborous insects, mollusc, fungi and other farm pests.

    Hence, this review summarizes the C. papaya L. latex potentials as pesticide, molluscicide and fungicide in order to pave the way for an alternate pests control without damaging the components of the ecosystem and environment.

  • Maktar, N. H., S. Kamis, F. Z. Mohd Yusof, and N. H. Hussain. “Erwinia papayae causing papaya dieback in Malaysia.” Plant Pathology 57, no. 4 (2008): 774-774.
  • Ortega, Monica Moralma Garces, “Effect of proteolytic enzyme and fiber of papaya fruit on human digestive health.” PhD diss., University of Illinois at Urbana-Champaign, 2011.
  • Pernezny, Ken, R.E. Litz, SOME COMMON DISEASES of PAPAYA in FLORIDA [PDF] University of Florida IFAS Extension, retrieved 2020/05/20, original source: https://ufdcimages.uflib.ufl.edu/IR/00/00/28/59/00001/VH05000.pdf

    Excerpt: Diseases are the most important limiting production problems of papaya. Although the plant is classified botanically as perennial, virus diseases have reduced the effective crop life to 1-2 years. This fact sheet describes the symptoms of several important Florida papaya diseases and recommendations for control.

    Since few pesticides are registered by the Environmental Protection Agency for use on papaya, and the plant is prone to damage by some chemical sprays, consult the University of Florida extension service or the Plant Disease Control Guide for current fungicide recommendations.

  • Persley, Denis M., and Randy C. Ploetzz. “1 7 Diseases of Papaya.” Diseases of Tropical Fruit Crops (2003): 373.
  • Plantvillage, Papaya (pawpaw) Description, photos, diseases,[web page] Website: https://plantvillage.psu.edu/ Email: [email protected] retrieved 2020/05/20 original source: https://plantvillage.psu.edu/topics/papaya-pawpaw/infos

    Website excerpt: PlantVillage is built on the premise that all knowledge that helps people grow food should be openly accessible to anyone on the planet. PlantVillage is a user moderated Q & A forum dedicated to the goal of helping people grow their own food. It is an open, freely available resource that helps you solve all your plant related questions.

  • Rampersad, Sephra N. “Molecular and phenotypic characterization of Colletotrichum species associated with anthracnose disease of papaya in Trinidad.” Plant Disease 95, no. 10 (2011): 1244-1254.
  • Singh, S. K., P. K. Jha, and P. K. Ray. “Papaya diseases in Bihar: an overview.” In II International Symposium on Papaya 851, pp. 481-486. 2008.
  • Streten, C., and K. S. Gibb. “Phytoplasma diseases in sub-tropical and tropical Australia.” Australasian Plant Pathology 35, no. 2 (2006): 129-146.
  • Vawdrey, L. L., K. R. E. Grice, and D. Westerhuis. “Field and laboratory evaluations of fungicides for the control of brown spot (Corynespora cassiicola) and black spot (Asperisporium caricae) of papaya in far north Queensland, Australia.” Australasian Plant Pathology 37, no. 6 (2008): 552-558.
  • Vawdrey, L. L., K. E. Grice, R. A. Peterson, and J. De Faveri. “The use of metalaxyl and potassium phosphonate, mounds, and organic and plastic mulches, for the management of Phytophthora root rot of papaya in far northern Queensland.” Australasian Plant Pathology 33, no. 1 (2004): 103-107.
  • Vawdrey, L. L., K. E. Grice, and R. A. Peterson. “7.3 The Use of Mounds and Organic and Plastic Mulches for the Management of Phytophthora Root Rot of Papaya in Northern Queensland.” [PDF] Diversity and Management of Phytophthora in Southeast Asia: 167. Retrieved 2016/07/04, original source https://core.ac.uk/download/files/153/6693118.pdf#page=166
    Abstract:

    Options for the control of root rot of papaya caused by Phytophthora palmivora were evaluated in a field experiment in northerly parts of Queensland, Australia. In the experiment, growing papaya on 0.75 m mounds reduced the incidence of root rot by 38.4% and significantly increased fruit yield.

    Soil covers of 2 m wide plastic mulch and organic mulch, in combination with 0.75 m mounds, further reduced plant losses by 20 and 10%, respectively.

    Plastic mulch on flat ground was as effective as the mounded treatments in reducing the incidence of root rot and increasing yield.

  • Zentmyer, G. A., Nishijima, W. T., Rohrbach, K. G. & Ohr, H. D. (eds) (1994). Compendium of Tropical Fruit Diseases. American Phytopathological Society Press
  • Reader Comments & Q&A

    On 2020-05-20 – by (mod) – white veins in papaya not actual “plant disease”

    Gracias por el foto y su comentario.

    I also live in Mexico and have opened a papaya to find the same white striations – though not often.

    I don’t think it’s an insect nor a plant disease but rather a growth abnormality, because having reviewed quite a few articles on payapa “disease” I have not found a photo nor descriptions of quite what you and I are seeing in these Mexican papayas; I agree that the papaya taste was the same.

    [Click to enlarge any image]

    I just found the fruit so unappealing that I threw it out. I’m researching further to see if I can put a name to this symptom and will post that here.

    As we wrote above,

    It appears that something has affected the laticifers (latex ducts) or the vascular material resulting in an aberration of the tissue.

    It is difficult to determine the actual cause without having knowledge of the growing conditions, variety, field and postharvest treatments, incidence and severity (eg. one fruit on one plant).

    My request to a papaya expert in Austraila expressed that view, as you’ll see in the article above.

    On 2020-05-20 by Melissa Saravia

    I live in Mexico and yesterday I opened a papaya that had this exact characteristic. [photo above]

    I did not find the taste was different, I did not find any insects, thinking it could make those burrows.

    On 2018-04-03 – by (mod) – white streaks in papaya ok to eat?

    Thanks for asking, Bree.

    In the papaya disease article above I quoted from experts who agreed that the white streaks are not associated with any disease.

    They were, of course referring to plant disease. It’s reasonable to infer that if the streaky papaya is not suffering a plant disease it’s also not a health hazard.

    I would prefer not to eat Papaya that has a lot of those white streaks because it’s its texture not so nice as its sisters, but on researching I have not found any expert who claimed that there was any health hazard.

    On 2018-04-03 – by (mod) – streaky papaya problem – ok to eat

    Thanks for asking, Bree.

    In the papaya disease article above I quoted from experts who agreed that the white streaks are not associated with any disease. They were, of course referring to plant disease. It’s reasonable to infer that if the streaky papaya is not suffering a plant disease it’s also not a health hazard.

    On 2018-04-03 by Bree

    Sorry, maybe I’m stupid or blind but I don’t see where the answer is. Is a papaya with these white spots/streaks ok to eat?

    I opened one today with these white spots. It smells good and seems normal besides the white spots. Just wondering if its safe to eat or if I should throw it away.

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    Technical Reviewers & References

    • Adkins and Adkins Dictionary of Roman Religion discusses Robigus, the Roman god of crop protection and the legendary progenitor of wheat rust fungus.
    • Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
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  • Papaya Disease & White Growth Anomaly Photographs Photos of stringy sinuous white growth in the fruit of the Papaya (pawpaw) ( Carica papaya L.) InspectAPedia tolerates no conflicts of