Since man first grew crops on calcareous soils he has probably been troubled with what we today call lime-induced chlorosis. This chlorosis has determined whether he grew certain desirable ornamentals or crops or whether he had to substitute others which were less desirable. Lime-induced chlorosis is spread world wide. It has been reported in the vine and fruit growing regions of Europe, in the chernozem soils of Russia, and many other areas where the rainfall is relatively low and the soil is relatively high in calcium carbonate. In the United States it most frequently occurs where the average annual rainfall is less than 30 inches. The conditions causing chlorosis are not stable, for it varies from year to year and even from week to week with changing conditions in climate and soil. An estimated 500,000 acres of crops grown in the western United States on calcareous soils are subject to moderate to severe chlorosis. This physiological malady has challenged the technical ingenuity of outstanding plant and soil scientists. The exact cause or causes have never been isolated; consequently no permanent preventative measures or cures can, as yet, be recommended.