Introduction
The cowpea chlorotic mottle virus (CCMV) has been identified in the United States, Cuba, and Nigeria. All strains of CCMV can infect soybean and may cause locally significant yield losses. It is only occasionally observed in North and South Carolina as well as Georgia, and does not cause significant impacts to soybean producers in the region.
Pathogen
Cowpea chlorotic mottle virus (CCMV) is a member of the genus Bromovirus.
Symptoms
Symptoms of infected plants can vary based on the level of cultivar susceptibility. Susceptible cultivars can show severe stunting and mosaic. Leaves may appear distorted with irregular chlorosis. Intermediate cultivars infected with CCMV produce interveinal chlorosis. Infection in resistant cultivars may only develop local lesions. Infected plants may produce fewer seed. Some changes to seed oil and protein composition can occur; however, not usually enough to affect their value.
Figure 1. Leaf mottling caused by cowpea chlorotic mottle virus (CCMV).
Photo courtesy of Steve Koenning
Disease Cycle
CCMV is sap transmissible and may also be transmitted by certain leaf-feeding beetles depending on the strain of virus. There is no evidence of seed transmission. Once a plant is infected, symptoms of leaf distortion and discoloration may be observed. Bean leaf beetle and cucumber beetle may vector the virus in this area. The virus may infect cowpeas and soybeans, but other legumes may allow the virus to overwinter.
Management
Management for this virus is typically unnecessary in North Carolina soybeans. While some leaf-feeding beetles are capable of transmitting CCMV, they do so with low efficiency and do not typically pose a large threat of spreading this virus within a field. Insecticides to manage the vector are not recommended.
Useful Resources
The NC State University Plant Disease and Insect Clinic provides diagnostics and control recommendations.
The NC State Extension Plant Pathology portal provides information on crop disease management.
The North Carolina Agricultural Chemicals Manual provides pesticide information for common diseases of North Carolina. The manual recommendations do not replace those described on the pesticide label, and the label must be followed.
Acknowledgments
This factsheet was prepared by the NC State University Field Crops and Tobacco Pathology Lab in 2020.
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Publication date: Sept. 10, 2020
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