Tristeza virus

Disease name: Tristeza virus

The scientific name: tristeza

Type of disease: viral

Disease family: Closterovirus

(Attacking a virus tristezalemon plant)

• The causes of disease:

Virus strains are transmitted tristeza Through the black aphid, by sucking the juice of the infected plant and transferring it to the healthy plant, and it can be transmitted through vaccination with materials contaminated with the virus. The disease can be detected in the laboratory by conducting an ELISA or PCR test.

• Symptoms of the disease:

Symptoms usually appear within 2-6 months. Leaves infected with Tristeza appear light green, yellowing of seedlings and the appearance of holes in the trunk and stem due to a lack of chlorophyll, and as the virus spreads, the leaves fall.

• Disease development cycle:

The Tristeza virus may spread rapidly and show its effect within days, or it may spread slowly and the tree remains infected for months to years. This is due to the severity of the infection and the availability of suitable conditions for the spread of the virus, as the black aphid loses its ability to transmit the disease within 24-48 hours.

• Conditions suitable for the spread of the disease:

Tristeza symptoms appear most clearly during the hot summer months, as it needs (20-25) degrees Celsius to reproduce and spread rapidly.

(Image showing Tristeza virus)

• Losses resulting from the spread of the disease:

A severe and rapid infection with the disease may lead to the death of the plant, while in the case of a minor infection, losses are less, as the virus may affect the quality and quantity of the fruits and the health of the plant in general.

• Control:

1. Replace trees severely diseased by the virus with healthy, disease-resistant trees.
2. Controlling aphids in nurseries to protect trees used as buds.
3. Controlling aphids through pyritium and agricultural soap.
4. Wash the plant with water to remove aphids.

(Lemon leaves infected with Tristeza virus)

• preventive measures:

1. Use virus-free and resistant seedlings.
2. Quarantine the plant infected with the virus from the rest of the field.
3. Use virus-free buds.
4. Monitor the field to avoid black aphid infestation.
5. Sterilization of agricultural tools used in the field.

• Sources:
• https://ipm.ucanr.edu/agriculture/citrus/tristeza-disease-complex/
• https://apps.lucidcentral.org/pppw_v10/text/web_full/entities/citrus_tristeza_disease_250.htm
• https://plantix.net/ar/library/plant-diseases/200025/citrus-tristeza-virus/