Papaya ring spot disease is caused by a virus called Papaya Ring Spot Virus-Type P (PRSV-P). It is an RNA virus. This virus is rod-shaped, unenveloped, 760-800 nanometers long and 12 nanometers wide. This virus causes mosaic disease in cucurbits.

Papaya stem, leaf and fruit are affected by ring spot disease. Bangladesh, India, Taiwan, China, Thailand, Caribbean Islands, South America, Florida, Hawaiian Islands, Texas and Philippines have high prevalence of this disease. In 1949, plant pathologist Jenson named the disease ring spot. Dr. Siddiq Publications
Causes of papaya ring spot disease
Papaya ring spot disease is caused by a virus called Papaya Ring Spot Virus-Type P (PRSV-P). It is an RNA virus. This virus is rod-shaped, unenveloped, 760-800 nanometers long and 12 nanometers wide. This virus causes mosaic disease in cucurbits.

Infection of papaya ring spot disease
Papaya ring spot virus is transmitted by whitefly (Myzus persicae) and jab beetle (Aphis gossypii). The virus infects the insect’s body within 15 seconds after the jab beetle feeds on a diseased plant. The insect becomes infected when it comes in contact with healthy plants. If the plant is dense, the disease spreads very quickly.

Symptoms of papaya ring spot disease
1. Stem disease symptoms
(i) The symptoms of the disease appear within 30-40 weeks
(ii) Diseased plants are stunted.
(iii) Dark green scaly spots appear on the stem.
(iv) Growth is stunted when young plants become diseased.
(v) Cracks are seen in the tree when disease incidence is high.
(vi) In the extreme stage of the disease the plant rots and dies.
2. Leaf disease symptoms
(i) Disease symptoms first appear on relatively young leaves.
(ii) Chlorosis occurs in leaves. The leaves are yellow in color.
(iii) Leaves are shriveled, small and deformed.
(iv) Diseased leaves show a greenish-yellow pattern.
(v) Round water-soaked spots are seen at the base of petioles.
(vi) Ring spots and distortion ring spots (mosaic) are seen on leaves.
(vii) Volume of diseased leaves decreases.
(viii) If the attack is severe, some small, deformed leaves can be observed on the plant head. Sometimes leaves have only veins.
3. As a result, the symptoms of the disease
(i) Resulting in circular spots or rings of dark green colour.
(ii) Water-soaked spherical spots form on the fruit and the space between the spots becomes hard.
(iii) Swollen areas are seen in diseased fruits.
(iv) When the fruit matures or turns yellow, the spots become indistinct.
(v) Sweetness and papain decrease in papaya.
(vi) Diseased fruits become smaller and drop off.
(vii) Young plants never bear fruit if diseased.
(viii) The tree does not bear fruit and the yield is reduced by 90%.
Cure/Control of Papaya Ring Spot Disease
1. Diseased trees should be removed and buried or burned.
2. Pesticides should be used on diseased land.
3. Cover the entire land with netting to prevent Aphids.
4. To kill aphids, pesticides like Ragor, Roxin, Perfection 40 EC, Metasystox 25 EC etc. should be sprayed.
5. Regular spraying of pesticides from the beginning of planting prevents disease spread by aphids.
6. Pruning of diseased plants should be stopped. Because the virus can spread from the cut.
7. Jab beetle population must be controlled.
8. Other species should be planted around the papaya plantation and between the rows of trees. It will reduce the infection.
Prevention of papaya ring spot disease
1. Healthy, vigorous and disease free varieties should be used as seeds.
2. Aphids must use nets to prevent insects.
3. Papaya cultivation should be stopped in diseased areas.
4. In the process of cross protection, a weak strain of the virus should be introduced into the papaya plant to make it resistant to the disease. Dr. Siddique Publications
5. Transgenic papaya varieties should be cultivated. Tunsgenic papayas are Rainbow, Sunup etc.
6. New seedlings should not be planted around or within diseased gardens.
7. Mixed farming system should be introduced. Dr. Siddiq Publications
8. Quarantine procedures should be adopted.

Virus that cause disease in new host species from the original host are called emerging virus. For example, birds are the primary host of bird flu and influenza virus and monkeys are the host of HIV. They later cause disease in human body. Emerging virus like HIV, SARS, Nile, Ebola etc. Dr. Siddiq Publications

A satellite is a nucleic acid entity that can replicate with other viruses. When the satellite is coated with a protein coat, it is called a satellite virus.

A kind of infectious entity made up of only protein which is about 100 times smaller than virus and causes disease in the host body is called prion. They are different from viruses. It is Kuru and Creutzfeldt disease of human central nervous system; Responsible for scrapie disease and mad cow disease in sheep and goats. Stanley Prusiner first observed this disease in 1982. He was awarded the Nobel Prize in 1997 for the discovery of this bacterium.

A microscopic microorganism made up of small RNA that spreads like a virus and causes various diseases in the body is called a viroid. It is composed of single-stranded and several hundred nucleotides. It is much smaller than a virus. Viroids cause a variety of plant diseases. It causes spindle tuber of potato, cadang cadang of coconut and sunbeach disease of avocado. Hepatitis-D is caused by a virus. Theodore Diener and Rainer (1967) discovered this.

Nucleocapsid is a non-infectious virus composed of nucleic acid and capsid.

An infectious virus composed of nucleic acid and capsid is called virion. It contains 2000-2130 capsomeres.

1. Vaccination or vaccine Vaccines are made from virus to prevent some diseases caused by viruses. Vaccines for smallpox, polio, dropsy, jaundice, cholera, plague, blood dysentery, typhoid etc. are made from virus.
2. Some phage virus are used as medicine in bacterial diseases like cholera, typhoid, dysentery and plague. Dr. Siddiq Publications

1. Human Diseases: Virus cause serious diseases like human measles, polio, rabies, influenza, jaundice, herpes, dengue, hepatitis, Ebola, AIDS, SARS, swine flu, cancer etc. Virus that cause cancer in the human body are called oncogenic virus. DNA viruses that cause cancer are called simian and RNA viruses are called retroviruses. Human papillary virus (HPV) causes tumors, Kaposi sarcoma herpes virus (KSHV) causes skin cancer and hepatitis-C virus causes liver cirrhosis.
2. Plant Diseases: Diseases like plant mosaic, leafroll, tomato bushistant, rice tungro, papaya ring spot, banana bunchy top etc. are caused by virus. About 300 plant diseases are caused by virus and reduce yields.
3. Cattle Diseases: Bovine Spring Disease; Foot and mouth disease in cattle, buffalo, sheep, goats, pigs, etc. and rabies in dogs and cats are caused by virus.
4. Poultry Diseases: Poultry diseases such as avian, influenza, bird flu, swine flu etc. are caused by virus.
5. Silkworm disease: Nuclear polyhedrosis virus (NPV) causes silkworm disease. This resulted in a disaster in the silk industry. Dr. Siddiq Publications
6. Death disease AIDS: AIDS is the most discussed viral disease in the world today. This disease is caused by HIV. Due to this disease, the immune system of the body decreases and people die.
7. Hepatitis or Jaundice: Jaundice is caused by hepatitis-A, B, C, D and E virus. This virus causes cirrhosis of the liver. The level of bilirubin in the blood increases. The skin of the body, face, eyes and saliva are yellow in color. The color of urine is dark yellow. Head, muscle and bone pain. Water accumulates in the stomach and legs. Dr. Siddiq Publications
8. Ebola Virus: The Ebola virus causes various cells in the body to burst. Bleeding from the eyes, nose, ears and throat. The body aches and the patient feels restless.
9. Bird Flu: Bird flu is caused by Avian Influenza Virus. Due to this virus, the body is infected. Body aches. Ga massas massas. Cold, sneezing and coughing. Headache and muscle pain. Nausea and vomiting. Diarrhea occurs.
10. Swine flu: Swine flu is caused by Swine Influenza Virus. This virus causes chills and irritation. Runny nose, itchy throat and cough. Eyes sting and water. Body aches. Shortness of breath. Diarrhea occurs. The body becomes weak, tired and hungry.
11. Zika virus: The Zika virus is spread by mosquitoes. This virus causes red spots or rashes on the body. Headache and lethargy occur. Muscle aches. Body aches. The eyes become red, the eyes hurt and it is called conjunctivitis. Chills and fever in the body. Arthritis and joint pain in the body.
12. SARS virus: SARS (Severe Acute Respiratory Syndrome) is a deadly virus. This virus causes headaches. Muscle aches. Cough. Dyspnea and pneumonia occur.
13. Sars Corona Virus: Severe Acute Respiratory Syndrome The disease caused by coronavirus is called SARS. The disease is transmitted from bats to humans. In 2003, about 800 people died in China, Taiwan, Canada and other countries due to Sars disease.
14. MERS Corona Virus: The disease caused by Middle East Respiratory Syndrome Coronavirus is called MERS. The disease is transmitted from bats to humans. In 2003, Mars disease killed many people in the Middle East.
15. Sars Corona Virus-2: Severe Acute Respiratory Syndrome The disease caused by Coronavirus-2 is called SARS-2. The disease is globally known as COVID-19. Humans have been infected from bats in Yunnan, China. Six million people died from the disease from 2019-2023. Dr. Siddiq Publications
16. Nipah virus: Nipah is an RNA virus. Bats are carriers of this virus. The human body is infected through the juice of raw dates. This virus causes dizziness and headaches. Muscle and throat pain. Trincha occurs, the patient becomes unconscious. Pneumonia occurs and acute respiratory distress occurs.
17. Chikungunya: Chikungunya is an α-virus (RNA). The attack of this virus causes severe headache. Rash on the body. The body becomes weak. Joint pain in body joints. Body feels cold and has high fever. Nausea and vomiting. Red rash can be seen on the skin