Symptom Identification and Control Methods of Carnation Viral Diseases
Carnation viral disease is a worldwide disease, occurring in all cultivation regions. The common viral diseases are vein mottle disease, necrotic spot disease, etched ring disease, and latent disease. Viruses often cause carnations to grow weakly, with short flower stems, smaller flowers, mottled petals, and split calyces, severely affecting the quality and yield of cut flowers.
(1) Carnation necrotic spot disease: the middle leaves of infected plants turn grayish-white, showing pale yellow necrotic mottling, or irregularly shaped streaks or stripes. The lower leaves often show purplish-red streaks or stripes. As the plant grows, symptoms spread upward, and in severe cases, the leaves wither, yellow, and become necrotic. The pathogen causing this disease is Carnation Necrotic Fleck Virus (CaNFV). The virus is mainly transmitted by aphids. Under normal circumstances, it is difficult to inoculate with sap. However, inoculation on Sweet William (Dianthus barbatus) is easily successful, and it can serve as a diagnostic host for Carnation Necrotic Fleck Virus.
(2) Carnation vein mottle disease: this disease produces systemic mosaic and petal color-breaking on carnation, China pink (Dianthus chinensis), and Sweet William (Dianthus barbatus). At the seedling stage, symptoms are not obvious; as the plant grows, viral symptoms worsen. In winter, old leaves often show latent symptoms. The pathogen causing this disease is Carnation Vein Mottle Virus (CaVMV). This virus is mainly transmitted through sap, and the green peach aphid is also an important transmission vector. During horticultural operations such as pinching, bud removal, and flower harvesting, the virus can be transmitted through hands and tools.
(3) Carnation etched ring disease: when large-flowered carnation varieties are affected, infected plants develop ring-patterned, ring-shaped, or broad striped necrotic spots on the leaves, most obvious at the seedling stage. In severe cases, many grayish-white ring-patterned spots can merge into large lesions, causing leaves to curl and become deformed. This disease shows latent symptoms in high-temperature seasons. The pathogen of this disease is Carnation Etched Ring Virus (CaERV). This disease is mainly transmitted through sap and aphids. In addition, plant friction contact and horticultural tools can also transmit the virus.
(4) Carnation latent viral disease: this disease is also called carnation symptomless viral disease. It generally shows no symptoms, or produces mild mosaic symptoms. When co-infected with Carnation Vein Mottle Virus, it produces mosaic symptoms. The pathogen of this disease is Carnation Latent Virus (CaLV). This disease is mainly transmitted through sap and the green peach aphid.
Control: ① Strengthen quarantine: at present, almost all carnation varieties cultivated in China are introduced from abroad, and these imported seedlings carry some kind of virus to a certain extent, so quarantine work must be strictly controlled to prevent viral diseases from breaking out on a large scale in China. ② When production units propagate young plants, cuttings must be taken from healthy, disease-free mother plants. Establish virus-free mother plant gardens specifically for cutting collection. Through shoot-tip virus elimination tissue culture, propagate seedlings for production. ③ In the carnation cut flower production process, avoid human transmission, such as in field sanitation management, pruning, pinching, and bud removal, paying attention to disinfecting hands and tools. ④ Regularly spray insecticides to prevent insects, preventing insect transmission of viral diseases.