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Viral diseases

What is a disease

Disease is an impairment of the normal state of the plant or of any of its components that interupts or modifies the performance of the vital function, being a response to environmental factors, to specific infective agents, to inherent defects of the plant, or to combinations of these factors.

What is a virus

Virus is a strand of DNA or RNA, consisting of nucleic acid wrapped in a thin coat of protein. It is very infectious that multiplies itself only within the cells of the living hosts.

Signs and symptoms of viral disease

Leaf curl causes the leaf margin to roll either inward or upward and is rather stiff with yellowish margin. The leaves become thicker than normal, with leathery texture.

nMosaic causes the normal green color of leaves to become mottled with light green, yellow, yellow-orange, or white irregularly shaped patches. If often results in the yellowing of the plants (chlorosis).

Ring spot causes ring of pale or yellow spots on the leaves.

Rosetting causes short and bushy growth. The leaves and the side branches grow in a crowded circles from a common center or crown, that they grow in a rosette (rose-liked form), hence the name.

Stunted growth causes the plant to be dwarfed and of inferior size and quality.

Prevention and control

  1. Always practice proper field sanitation.
  2. Use of resistant cultivars.
  3. During transplanting, refrain from smoking and must wash hands thoroughly with soap and water.
  4. Control insect pests that are normally the carriers of viral disease; like aphids, leafhoppers, and whiteflies
  5. Protect your seedlings with row covers to prevent them from early attack of the abovementioned pests.
  6. Uproot the heavily infected plants. Never transplant where the diseased plant was removed. Wash hands with soap and water before tending the healthy plants.
  7. Control the weeds.
  8. Always remember not to work on your plants when they are wet.
  9. After a heavy viral infection, plow the field and fallow the area.
  10. Ask for assistance from your local agricultural office for proper advice.


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