What is Papaya Ringspot disease ? 

The Papaya Ringspot disease caused by Papaya Ringspot Virus (PRSV) is one of the most significant viral diseases affecting papaya (Carica papaya) crop worldwide leading to severe yield losses and is a threat to the papaya industry in many tropical and subtropical regions.

What is Papaya Ringspot Virus (PRSV)?

Papaya Ringspot Virus (PRSV) is a member of the genus: Potyvirus; Family: Potyviridae, and it primarily infects papaya plants, although it can also affect other members of the Caricaceae family and certain Cucurbitaceae plants. The virus is known for causing distinct ring-shaped lesions on the fruits, which is where its name originates. 

Category: Viral disease

Main affected plant part: Leaves and fruits  

Symptoms of disease infection 

Symptoms of Papaya Ringspot Virus (PRSV) on Papaya Leaves

1. Initial Chlorosis and Vein Clearing

In the early stages of papaya ringspot virus (PRSV) infection, papaya leaves exhibit light green to yellowish chlorotic patches, typically starting near the veins. These patches are irregular and diffuse. Simultaneously, there is vein clearing, where the veins lose their green pigmentation and appear translucent. These subtle signs are often mistaken for nutrient deficiency but are key early indicators of viral activity.

2. Mosaic Pattern Development

As the virus progresses, the chlorotic patches become more defined, leading to a mosaic pattern — alternating light and dark green zones across the leaf surface. This symptom is most prominent on young, developing leaves, indicating active viral replication and systemic spread within the plant. The affected leaves may remain functional but are often weaker and more susceptible to other stresses.

3. Puckering and Leaf Deformation

With continued infection, the leaves begin to pucker and curl. This puckering is due to uneven growth of leaf tissues, caused by disrupted cellular function and nutrient imbalance. The leaf surface becomes rough, wrinkled, and sometimes blistered. These symptoms reflect the internal stress the plant endures due to viral interference in protein synthesis and hormonal signaling.

4. Shoestring Symptoms (Severe Infection)

In advanced cases, especially when infection occurs at an early vegetative stage, the leaf blades fail to expand properly. They become narrow, string-like, and elongated, a condition known as “shoestring symptoms.” These malformed leaves resemble ribbons and severely limit photosynthesis, leading to stunted growth and poor yield potential. This symptom is a hallmark of early-stage systemic viral infection.

5. Rosette Appearance and Stunting

As infection persists, the newly formed leaves become progressively smaller and more clustered, creating a rosette-like appearance at the plant’s apex. The leaves also tend to turn pale yellow or become distorted. The entire plant often becomes stunted, with shortened internodes and reduced canopy volume. This stage indicates systemic failure in nutrient transport and growth regulation.

 Symptoms of Papaya Ringspot Virus (PRSV) on Papaya Fruits

1. Early Fruit Stage – Oil Spots

Infected papaya fruits begin to show small, dark green oily spots during the early development stages. These spots are superficial and may not always be noticed immediately. They indicate initial virus replication near the fruit surface. These oil spots resemble scale insect damage but are viral in origin and usually remain fixed in shape and size.

2. Classic Ring Spot Formation

As fruits enlarge, the most recognizable symptom — ring spots — begin to appear. These are circular or concentric green rings with clear centers, often resembling a target board. These spots are either slightly sunken or rough to the touch. They do not disappear with ripening and remain a permanent visual marker of viral infection, severely impacting the fruit’s marketability.

3. Fruit Deformities and Quality Loss

In advanced infections, affected fruits may become misshapen, underdeveloped, or unevenly ripened. Internal tissue quality is compromised, with lower sugar content (low BRIX) and a mealy or watery texture. The flavor is often diminished, and such fruits fail to meet market standards. These deformities result from the virus interfering with carbohydrate transport and hormonal balance during fruit development. In severe cases, infected papayas may fall prematurely (Premature Fruit Drop) from the tree.

Symptoms of Papaya Ringspot Virus (PRSV) on Papaya Stem Region

The stem symptoms of Papaya Ringspot Virus (PRSV) are visually distinctive and play a key role in early disease identification, especially in combination with leaf and fruit signs. One of the most characteristic symptoms is the appearance of elongated dark green streaks or bands along the length of the main stem and petioles (leaf stalks). These streaks are usually linear, run parallel to the stem, and are sometimes slightly sunken. In younger plants, these may initially appear as faint or oily lines but become more prominent as the infection advances.

As the disease progresses, the dark green streaks may merge, forming irregular blotches or mosaic-like bands along the stem. These discolorations are caused by viral disruption of normal pigment distribution in the epidermal and cortical layers of the plant. Unlike fungal or bacterial infections, these marks are not soft, raised, or sunken lesions — they remain flat and pigmented, making them easy to distinguish from other stem diseases.

Infected petioles (the stalks that attach leaves to the stem) also develop similar green streaks, often twisting slightly and becoming brittle. This can result in premature leaf drop or petiole breakage, especially under windy or dry conditions.

In severe cases, particularly in young papaya plants infected early, the entire stem becomes discolored and stunted, affecting nutrient transport and structural strength. These plants may fail to develop a proper trunk or exhibit crooked or compressed growth, with multiple bends and suppressed internode elongation. The vascular tissue inside the stem may remain unaffected initially, but prolonged infection can interfere with phloem function, leading to wilting and dieback.

Here are images showing different symptoms of Papaya Ringspot Virus (PRSV) – 

Favorable Conditions for Pathogen Multiplication 

PRSV thrives under certain environmental conditions:

• Warm Temperatures: PRSV is most prevalent in tropical and subtropical climates. The virus prefers warm temperatures ranging from 25°C to 35°C (77°F to 95°F). These conditions are optimal for both viral replication and the activity of aphid vectors.
• High Humidity: Papaya plants are often grown in areas with high humidity, which supports the proliferation of aphids and other vectors that transmit the virus. 
• Plant Stress: Stressed plants, particularly those with poor/ inadequate nutrition or inadequate irrigation, are more vulnerable to viral infections. This is why maintaining healthy plants and nutrient management is critical for reducing the impact of PRSV.

Mode of Infection & Spread 

Primary Mode of Infection:

• Infected Seedlings or Transplants: One of the primary ways papaya ringspot virus (PRSV) spreads initially is through infected seeds. The virus can be present in papaya seeds, which, when planted, lead to new infected plants. This is why it is essential to use virus-free seeds or certified healthy transplants to avoid introducing the virus into a new plantation.
• Perennial Hosts: In some regions, certain wild species and perennial plants that host the virus act as reservoirs for the pathogen. These reservoirs play a critical role in maintaining the virus in the field.

Secondary Mode of Infection:

• Mechanical Transmission: Another way the virus can spread is through mechanical means. Tools, hands, and other farm equipment contaminated with infected plant material can inadvertently spread the virus to healthy plants. 
• Insect Vectors (Aphids): The secondary mode of infection primarily involves aphids, particularly Aphis gossypii and Myzus persicae , which act as the main vector for PRSV transmission. Aphids acquire the virus when they feed on the sap of infected plants and then transmit it to healthy plants through their feeding activities. In this case, Aphid transmits virus in Non-persistent manner

Aphids Acquire the Virus: When aphids feed on an infected plant, they acquire the virus. The virus enters the aphid’s digestive system and remains there for a period of time.

Virus Transmission: Once the aphid has acquired the virus, it can transmit it to healthy plants when it feeds on them. The virus is spread through stylet-borne transmission, where the aphid’s feeding tube transmits the virus into the plant.

• Transmission- Aphid feeds on infected plants, picks up the virus 
• Entry- Virus enters a healthy plant through an aphid’s feeding wound
• Uncoating- Virus sheds its protein coat, releasing RNA genome
• Replication- Viral RNA hijacks the plant’s machinery to replicate
• Protein Synthesis- Virus produces structural and movement proteins 
• Assembly- New virus particles assemble in the cytoplasm 
• Cell-to-Cell Movement- Virus moves through plasmodesmata between cells
• Systemic Spread- Virus enters the phloem, spreading to other parts of the plant 
• Symptom Development- Leaves show mosaic patterns, and fruits develop ring spots 
• Cycle Repeats- Aphids feed on infected plants, spreading the virus to new plants

Papaya Ringspot Disease Management 

Papaya Ringspot Virus (PRV) causes a deadly disease of papaya that severely reduces production and kills the plants. Primarily it spreads by infected seedlings and secondary due to insect vectors. Early detection of infected plants and prompt removal can check the spread of the disease. So, it is necessary to control insect vectors as well as to use healthy disease free planting materials.  

Here are some tactics to manage Papaya Ringspot Virus

Healthy Planting Material:  Use disease-free seedlings or raise the seedlings in a nursery where there are insect-proof nets and structures are available. 

Cultural control: Raise sorghum/maize as a barrier crop before planting papaya. They will be acting as a physical barrier and a “sink” for virus infection. 

Proper Planting Practices: Ensuring proper field hygiene, including the removal of infected plant material, helps reduce the spread of the virus within the plantation. Do not raise cucurbits around the papaya field as they can serve as a reservoir for aphids.  

Proper Spacing: Adequate spacing between plants can reduce the chances of aphid transmission from plant to plant.

Avoid excess nitrogen fertilizer: Lush growth attracts more aphids.

Removal of Weeds and Infected Plants: Rough out cucurbit weeds if grown near papaya fields. Regular inspection of papaya plants for symptoms of PRSV is essential. Infected plants should be removed and destroyed promptly to reduce the risk of spreading the virus to other plants. 

Vector Control (Aphid Management): Regular use of Huntin’s Recommendation to control aphid population can help to reduce the spread of PRSV. Use of  Yellow Sticky trap.

Huntin’s Recommendation  

Spray of All-rounder @ 2 ml / L + Nanosulf @ 1 ml / L + Nanoreach @ 1 ml / L water on nursery plants to avoid aphid infestation. Growing papaya in a virus-free nursery with strict protocols for hygiene can minimize the risk of viral contamination before the plant. 

For Prevention:

Soil Application of – Seed Grow ++ @ 1 Litre per Acre at interval of every 10 – 15 days

First application immediately after TRANSPLANTING, during first irrigation so to avoid transplanting shock. And repeat this application at interval of every 10 – 15 days

Spray of – Disnil (Virus) @ 1.5 ml / L + Nanosulf @ 2 ml / L + Nanoreach @ 1ml / L water. Repeat this spray every 15 days to keep Virus under check on plant

For Cure:

Spray of – Disnil (Virus) @ 2.5 ml / L + Allrounder @ 2 ml / L  Nanosulf  @ 2 ml / L + Nanoreach @ 1 ml / L water at intervals of every 7 days.

Soil Application of – Seed Grow ++ @ 1 Litre per Acre at interval of every 7 days.

Repeat this above application every 7 days till the new shoots are free from virus infection and this may take upto 3 to 5 applications depending on severity of infection.

Once the new leaves and fruits are free from virus infection, no symptoms are visible; one can increase the time interval of spray from 7 days to 15 – 20 days. Same applicable for Seed Grow++. 

Before and After Treatment Result –

Explore step-by-step instructions to control the virus in our Papaya Treatment Plan on Huntin Organics.

A Brief Product Details :

Disnil (Virus) is an Organic product that triggers plant’s immunity system and signals plant to develop immunity against virus particle

Disnil – Huntinorganics 

Seed Grow ++ is a synergistic combination of highly effective 12 biological strains of Bacteria and Endo mycorrhizae that solubilize and mobilize the plant macro and micronutrients such as N, P, K, Ca, Mg, S, Si, Zn, etc that improves nutrient balance in plant, effective root development, stress management, improvement of soil structure.

Balanced nutrition is the most important factor in plants to fight against any disease. 

Seed Grow++ – Huntinorganics 

Nanosulf  is nano tech. based neem product containing sulphur and potash in nano forms

Nano Sulf – Huntinorganics 

Nanoreach is non-ionic based 100% pure silicone surfactant, spreader, adjuvant to  improve efficiency of every pesticide/weedicide/nutrients by high stomatal infiltration

Nano Reach – Huntinorganics 

All Rounder is neem based product having essential oil and several components of azadirachtin; product is having great emulsion and unique smell that makes it outstanding with unwavering stability during field application 

All Rounder – Huntinorganics  

Note: These products are safe for beneficial insect populations, including predatory beetles, ladybird beetles, lacewing larvae and parasitoid wasps

For more details on papaya diseases & insect pests, and their control, please visit- Papaya Crop