They are most often spread by splashing water. Fungal spores are larger than bacterial cells but are not visible without a microscope. Fungi are like small plants. Most plant diseases caused by fungi are most severe during periods of moderate temperatures and when water is retained on the leaves or fruit for an extended period of time. Many fungi are spread by wind, splashing rain and equipment.
Nematodes are small, worm-like animals which live in the soil.
They feed on plant roots, causing stunted plants. Root knot is the most damaging nematode in the home garden. It causes galls or knots on susceptible plants such as tomatoes, cucumbers, squash, beans and many other vegetables. Plant diseases are worst when light rain showers or heavy dews have fallen and when temperatures are mild. During these times, watch your garden closely for signs of disease.