Virus diseases are spread to healthy blueberry plants by vectors that include primarily aphids, nematodes, leafhoppers, and occasionally honeybees, which can spread virus-infected pollen. Virus diseases also are spread by diseased plants from infected nursery stock. Once a bush is infected with a virus, it remains infected for the life of the plant.
Virus diseases cannot be controlled like a fungal or bacterial disease with chemicals. Prevention and sanitation measures are the best control for virus diseases. Suggested control practices include planting virus-free clean stock plants in clean soil, destroying alternate hosts such as wild blueberries that may harbor viruses, removing and destroying plants that are diseased or suspected of having virus infections, and controlling insect and nematode vectors.
Blueberry scorch virus can cause severe flower and leaf browning in highbush blueberries. All varieties of highbush blueberry are considered susceptible.
The blueberry aphid spreads shoestring virus. There is a latent period of 4 years between infection of the plant and expression of symptoms. Shoestring-infected wild blueberries also have been found in the wooded areas.
Tomato ringspot virus is vectored by the dagger nematode. This virus can infect many different species of plants, including other fruit crops such as apples, peaches, and raspberries, and weeds such as chickweed and dandelion. Infection spreads slowly.
The cause of red ringspot virus is unknown. Mealybugs, however, may be involved in transmitting this virus.
Stunt is caused by a phytoplasma not a virus. Viruses and phytoplasmas are quite different, but they are often grouped together in discussions of plant pathogens.
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