Yellow dwarf virus on onion leaves

Disease name: Onion yellow dwarf virus

The scientific name: Onion yellow dwarf virus (OYDV)

Type of disease: viral

Disease family: Potyviridae

(The appearance of initial symptoms as a result of infection with the OYDV virus)

• The causes of disease:

The yellow dwarf virus targets onion plants and is transmitted mainly by aphids, which transmit it quickly to the plant and do not retain it for a long time. Therefore, controlling aphids does not prevent the infection from occurring, but it reduces the severity of the spread of the disease.

• Symptoms of the disease:

The initial symptoms of infection appear on the leaves, ranging from the appearance of yellow lines to complete yellowing of the leaf. The leaves become flat, wrinkled, and bend downward, and leaves close to the soil fall. Over time, the plants wither and become stunted, and the fruits usually remain firm but do not reach their full size.

(Development of OYDV infection on onion leaves)

• Disease development cycle:

The yellow dwarf virus is transmitted during vegetative propagation or through insects such as the green peach aphid in addition to other aphids, where it spreads the virus from one plant to another in a non-continuous manner.

• Conditions suitable for the spread of the disease:

The disease affects the plant throughout the season, but it may increase at the beginning of summer with the spread of aphids.

(Onion leaves curl and turn yellow as a result of infection with the OYDV virus)

• Losses resulting from the spread of the disease:

The virus stimulates the vegetative growth of onions during storage, and seeds taken from infected plants are of poor quality.

• Control:

1. Organic control: Getting rid of plant remains and weeds in the field and eradicating infected plants limits the spread of the virus, and using neem oil to combat aphids helps limit the spread of the disease.
2. Chemical control: There is no chemical pesticide that fights the virus.

• preventive measures:

1. Use disease-resistant varieties.
2. Planting in virus-free soil.
3. Sterilize agricultural tools before use.
4. Monitor the crop constantly for early detection of infection.

(Onion plants dwarf and wilt as a result of infection with the OYDV virus)

• Sources:
• https://ipm.ucanr.edu/agriculture/onion-and-garlic/onion-yellow-dwarf/
• https://www.vegetables.bayer.com/za/en-za/resources/disease-guides/onions/onion-yellow-dwarf.html