Leaf chlorophyll deficiency. Healthy leaf (left) and a leaf suffering from chlorosis (right). This is a condition where lack of chlorophyll (a green pigment found in leaves) causes a leaf to turn a pale green or yellow colour. Chlorophyll is needed by plants to produce food. Causes of chlorosis can include mineral deficiency (usually iron), damage to the plant's roots, or an alkaline soil. The last two causes prevent or reduce iron uptake from the soil. Iron is not found in chlorophyll, but is essential for its formation. Chlorosis treatment may involve adding nutrients to the plant directly or through the soil.