Citrus tristeza virus

Citrus tristeza virus (CTV) is a viral species of the genus Closterovirus that is primarily known for causing disease in citrus trees. The virus is transmitted by several species of aphids and is considered one of the most damaging citrus pathogens.

History

The Citrus tristeza virus was first identified in the 1930s in Brazil where it caused a severe epidemic of quick decline of sweet orange trees grafted on sour orange rootstock. The name "tristeza" is derived from the Portuguese word for sadness, reflecting the devastating impact of the disease on the citrus industry.

Symptoms

The symptoms of Citrus tristeza virus infection can vary greatly depending on the citrus variety and rootstock combination, as well as the strain of the virus. Symptoms can range from mild leaf curling and vein clearing to severe stem pitting, decline, and death. In some cases, infected trees may remain symptomless for several years.

Transmission

CTV is primarily transmitted by several species of aphids in a semi-persistent manner. The virus can also be spread through infected budwood used in propagation.

Management

Management of Citrus tristeza virus involves the use of virus-free propagation material, removal of infected trees, and control of aphid vectors. In some regions, resistant or tolerant rootstocks are used to mitigate the impact of the disease.

Economic Impact

The economic impact of Citrus tristeza virus is significant, particularly in regions where citrus is a major agricultural commodity. The virus has caused extensive losses in many citrus-growing regions around the world, including the United States, Brazil, and Spain.

Research

Research on Citrus tristeza virus is focused on understanding the virus's biology and epidemiology, developing effective management strategies, and breeding for resistance.