Magnesium deficiency in cut-flower chrysanthemums
A severe leaf yellowing, or chlorosis problem, has occurred in chrysanthemums at several commercial greenhouses in the San Francisco Bay Area. The disorder was found to be magnesium deficiency caused by high annual applications of potassium. Magnesium fertilization, even at high rates, was not effective in correcting the problem. Elimination of potassium fertilization gave immediate control.