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SYMPTOMS OF VIRAL DISEASES

In the previous example, ringspot symptoms were simply a discoloration of the plant tissue. No real tissue NECROSIS (death) occurred. In other viral infections, such as infection by impatiens necrotic spot virus or INSV (shown in this photo), both ringspotting and necrosis result (see arrow).

INSV is a very important virus in production of ornamental plants. It can infect a wide range of ornamentals. Once infected with INSV, plants should be destroyed. INSV is transmitted by thrips, a very common insect pest in greenhouses. If thrips are not kept under control, an entire greenhouse full of plants can very rapidly become infected with INSV.