Differences Between Bacterial & Viral Diseases of Plants

Bacteria Basics

• Bacteria are single-cell microorganisms; they are often rod-, sphere- or spiral-shaped. They are prokaryotic cells with an undefined nucleus. Bacteria are commonly found on the exterior of plant leaves, stems and other plant parts. They cause problems when they enter the plant through wounds and pores. Bacteria multiply rapidly under favorable conditions. One bacterium may multiple into millions within 12 hours. Insects, birds and garden tools transmit many bacterial diseases. Bacterial diseases cause leaf tip burns, leaf spots, blights, rots, scabs, cankers and wilts.

Virus Basics

• Viruses are extremely small, infectious particles that live and multiply inside living cells. Some are rod-shaped. Viruses usually enter plants through wounds. Once inside the plant, viruses move from cell to cell. Vectors carry them from plant to plant. A variety of insects including aphids and leafhoppers serve as vectors. Garden tools, seeds and pollen also carry viral diseases. Viral diseases may cause leaf mottling, curled or deformed leaves, and abnormal flowers and fruit.

Preventing Bacterial Diseases

• It is often easier to prevent rather than treat bacterial diseases. Bacteria multiply rapidly under crowded conditions with high humidity and poor air circulation. Preventing those conditions decreases the chance of spreading bacterial diseases. Water the plants regularly, plant the plants in suitable-size containers and provide adequate fertilizer. Use sterilized and well-drained soil in pots. Isolate sick plants and prune infected leaves with disinfected scissors. If the disease involves the entire plant, destroy the plant to stop the spread of the disease to healthy plants. Grow disease resistant varieties and cultivars.

Preventing Viral Diseases

• Viral diseases usually spread by contaminated equipment and insects. Sanitize tools, wash hands and wear disposable outerwear to help prevent the transmission of viral diseases. Use certified virus-free plants for planting and grafting. Remove diseased plants and control insects. Plant genetically resistant varieties.