Citrus blight, a disease of unknown etiology, is one of the most important citrus diseases in Florida, causing estimated yearly losses of $60 million, and speculated to be one of the oldest. Diseases similar or identical to blight occur in Brazil, Argentina, Australia, South Africa, Cuba, and Uruguay. The disease has been called declinio in Brazil, declinamiento in Argentina, and such things as young tree decline, sandhill decline, and rough lemon decline in Florida. Symptoms of the disease include a permanent wilt and decline of the tree canopy from which the trees never recover. Prior to canopy decline, leaves may show zinc deficiency symptoms. These zinc deficiency symptoms may vanish as the tree declines or may occur on any new flushes after initiation of decline. Leaves on affected trees are usually small in size as compared to those of healthy trees and have an off-green to gray color.