Seasonal development
and life cycle—Viruses
Viruses can be transmitted by insects, such as aphids or whiteflies feeding on plant sap, or mechanically
in sap that is spread by hand or grafting tools. Viruses also commonly spread in seed, pollen, or in vegetative
parts of plants used for propagation through budding and grafting. Once a plant becomes infected with
virus, it usually remains infected throughout its life.
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Green
peach aphid colony
Hand
tools can help spread viruses
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