Submitted to: Soybean Disease Compendium
Publication Type: Book / Chapter
Publication Acceptance Date: 8/10/1999
Publication Date: N/A
Technical Abstract: Most plant diseases are caused by eumycota fungi. Of the nearly 70,000 described species of fungi, more than 8,000 are known plant pathogens. The fungi are a diverse group of organisms that lack chlorophyll and cannot carry out photosynthesis. Instead they obtain sustenance from organic matter produced by other organisms. Fungi are adapted for survival in air, soil, and water and typically are in close association with other organisms. Many fungi enter soybean plants indirectly through natural openings, such as stomata, hydothodes, nectaries, and lenticels. In other cases they infect plants through wounds made by blowing sand, wind, hail, people, insects, equipment, nematodes, or other agents. Hyphae or specialized structures such as penetration pegs generally directly penetrate plant tissue through a combination of enzyme action and pressure. Fungi can overseason on or in living or dead plants, seeds, soil, and occasionally insects. Some fungi, in addition to growing in soybean plants, infect and reproduce in weeds or other hosts, where they can overseason.