- Virus symptoms often include color changes in the leaves such as a mosaic or mottled pattern of light and dark green. Other color changes could appear as ring patterns of light green or necrotic or bleached areas.
- Additional symptoms include stunted or malformed new growth, unusual flower colors, and dieback of terminal growth.
- These disease symptoms in many plants can be confused with nutritional deficiencies or environmental effects such as air pollution.
- Most plant viruses cause systemic infections and there is no cure for infected plants.
- Plant viruses are commonly spread from plant to plant by insects that feed on sap such as aphids, thrips, and white flies.
- Other common modes of virus dissemination include infected seeds, sap, divisions, grafted plant varieties, bulbs, and pollen.
- Viruses can also be spread by horticultural activities such as vegetative propagation and pruning.
- Many viruses can survive in weeds adjacent to the horticultural plants that become infected in our gardens.
Ringspot virus on mountain laurel. Photo: Penn State Department of Plant Pathology & Environmental Microbiology Archives , Penn State University, Bugwood.org
- The management of virus diseases often involves removal of the infected plant to prevent spread to adjacent healthy plants.
- Insect management is critical since viruses can also move through the garden in insects feeding on infected plants before feeding on near by healthy plants.
- Weed removal is also very important since they can be the primary source of infected plants where insects breed or overwinter before moving onto healthy plants in the garden.
- Never knowingly plant virus infected varieties into your garden. Purchase certified virus clean stock and be alert to remove plants that exhibit disease symptoms.