Single-cell microorganisms that reproduce by simple cell division. Rots cause decay of leaves, stems, branches, and tubers. Vascular system blockage causes wilting. Galls result from an overgrowth of the affected cells. Bacterial problems are encouraged by poor drainage, wet soil, high humidity and high temperatures. Feeding plants with slow-release natural organic fertilizers will help prevent bacterial infection. Use disease-free seed and resistant varieties. Remove infected plants promptly and compost. You need a microscope to see the actual bacteria, but the symptoms they cause are easy to see with the naked eye. Most bacteria break down dead organic matter and are beneficial. A few, however, cause plant diseases. Bacteria usually reproduce by splitting in half. Wind, water, insects, garden tools and gardeners’ hands spread the spores. Bacterial diseases are more difficult to control than fungal diseases but the hydrogen peroxide products are effective.