The noxious effects of saline irrigation waters on the growth and fruit production of citrus have been recognized for many years. Citrus trees are sensitive to relatively low concentrations of the salts of sodium, chlorine, and sulfur. Boron is toxic to citrus at concentrations of about 0.5 parts per million (ppm) and lithium at about 0.05 ppm. A number of interdependent factors determine the degree of success in the use of a given irrigation water. These include: total soluble salts and specific ion species, soil type and drainage characteristics, amounts of water used and method of application, cultural practices, climate, and the rootstock and associated scion variety.