ABSTRACT
Abiotic or noninfectious diseases are caused by cultural practices (Chapter 32) or environmental factors on plants in nature and also on cultivated crops (contrast with Chapter 36 for disease diagnosis). Although not true plant diseases (actually plant stress factors), damage by abiotic extremes such as light, water, and temperature can be quite severe under certain circumstances. Most plants grow best at optimum levels of environmental conditions. If, for example, temperature drops below or exceeds the optimum for growth, damage may occur. Also, although water is necessary for normal plant function, excessive amounts of water or insufficient amounts may cause injury.
