Stay Vigilant About Virus Threat

By Ozgur Batuman and Amit Levy

Citrus yellow vein clearing virus (CYVCV) was first reported on lemon and sour orange trees in Pakistan in 1988. Since then, the disease has been primarily restricted to Asian countries. However, CYVCV was more recently detected in dooryard citrus in California in 2022. While there is no indication that the virus is present in Florida citrus yet, it is important for growers to be familiar with the disease symptoms so they can stay vigilant about CYVCV’s threat to Florida should the virus be introduced.

CYVCV is an RNA virus (like citrus tristeza virus) that infects systemically and causes vein clearing (yellow veins) on young citrus leaves, especially on lemon and sour orange. It is transmitted through grafting, work equipment and phloem-feeding insects such as aphids and whiteflies. Severe infections lead to tree decline and reduced fruit yield and quality.

KNOW THE SYMPTOMS

CYVCV symptoms can vary depending on numerous factors, such as the viral isolate, citrus variety and environmental conditions like temperature. The symptoms can be reduced or disappear after the leaves mature or in high temperatures. Some leaves are crinkled and warped, with wavy edges that persist.

The typical symptoms in lemon or sour orange trees are yellow, clear veins and a water-soaked appearance in leaves (Figure 1). Symptoms of CYVCV on satsuma include slightly curled spring leaves, cracked and deformed leaf edges and malformed young fruits with groovelike depressions around the calix that resemble a pumpkin.

CYVCV is spreading rapidly and without symptoms in most citrus cultivars, causing a considerable loss to the lemon industry in many countries.

PREVENTION AND CONTROL

Climatic conditions are highly suited for establishing CYVCV, which is predicted to have an economic impact on citrus production in Florida if introduced. Preventing CYVCV from entering Florida is much easier than trying to eradicate or control it. Therefore, avoiding propagation materials from areas infected with the virus is essential.

CYVCV is mainly controlled by managing the insect vectors and disinfecting equipment. If you suspect CYVCV in your grove, contact the Florida Department of Agriculture and Consumer Services, your Extension specialist or the authors (obatuman@ufl.edu or amitlevy@ufl.edu) as soon as possible for diagnosis.

Ozgur Batuman and Amit Levy are associate professors at the University of Florida Institute of Food and Agricultural Sciences Southwest Florida Research and Education Center and Citrus Research and Education Center, respectively.

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