Plant Diseases

Like human beings and other animals, plants are subject to diseases. In order to maintain a sufficient food supply for the world's population, it is necessary for those involved in plant growth and management to find ways to combat plant diseases that are capable of destroying crops on a large scale. There are many branches of science that participate in the control of plant diseases. Among them are biochemistry, biotechnology, soil science, genetics and plant breeding, meteorology, mycology (fungi), nematology (nematodes), virology (viruses), and weed science. Chemistry, physics, and statistics also play a role in the scientific maintenance of plant health. The study of plant diseases is called plant pathology.

The most common diseases of cultivated plants are bacterial wilt, chestnut blight, potato late blight, rice blast, coffee rust, stem rust, downy mildew, ergot, root knot, and tobacco mosaic. This is a small list of the more than 50,000 diseases that attack plants. Diseases can be categorized as annihilating, devastating, limiting, or debilitating. As the term suggests, annihilating diseases can totally wipe out a crop, whereas a devastating plant disease may be severe for a time and then subside. Debilitating diseases weaken crops when they attack them successively over time and limiting diseases reduce the viability of growing the target crop, thereby reducing its economic value. Plant diseases are identified by both common and scientific names. The scientific name identifies both the genus and the species of the disease-causing agent.

For the past 50 years, the ability to combat plant diseases through the use of modern farm management methods, fertilization of crops, irrigation techniques, and pest control have made it possible for the United States to produce enough food to feed its population and to have surpluses for export. However, the use of pesticides, fungicides, herbicides, fertilizers and other chemicals to control plant diseases and increase crop yields also poses significant environmental risks. Air, water, and soil can become saturated with chemicals that can be harmful to human and ecosystem health.