How to Manage Pests

Pests in Gardens and Landscapes


Most flowers are susceptible to infection by one or more plant viruses. Viruses can slow plant growth and change the appearance of foliage, flowers, and fruits. Virus-infected leaves can become spotted, streaked, mottled, distorted, or stunted. Veins may lose their color or develop outgrowths. Flowers can be dwarfed, deformed, streaked, or faded, or they can remain green or develop into leaflike structures. Viruses usually infect through a wound. Many are transmitted by invertebrates, such as aphids and thrips, that feed on plant juices. Mites, nematodes and fungi can also transmit viruses. Viruses can spread in vegetative plant parts, such as cuttings from infected stock plants and in bulbs, corms, and rhizomes.


Viruses rarely kill woody plants, but can dramatically alter plant appearance, reducing the value. Herbaceous ornamentals and certain vegetables are generally more susceptible to serious injury or death from viruses, especially when plants are young. Most plants infected with a virus cannot be cured. Dig out and destroy virus-infected plants. Prevent spreading viruses by using good sanitation and cultural practices. Control nearby weeds that serve as reservoirs for viruses and insects. Use only virus-free plant material and consider growing virus-resistant cultivars if available.

Clorotic mottling and necrosis on Begonia
Virus-induced chlorotic mottling and necrosis on Begonia

Virus-infected alstroemeria plant
Virus-infected alstroemeria plant

Concentric ring spots caused by TSWV
Concentric ring spots caused by Tomato spotted wilt virus on impatiens

Statewide IPM Program, Agriculture and Natural Resources, University of California
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