Chlorosis is a symptom that arises when leaves of a plant cannot produce enough chlorophyll. The leaves lose their typical green color and turn yellow, pale green, or yellowish-white.
Inability to make chlorophyll directly affects the plant's ability to produce carbohydrates. The plant could die unless it is treated.
Unfortunately, chlorosis is a symptom for many plant disorders and diseases, and an expert should be consulted when chlorosis is present.
Causes could be, but are not confined to, high pH in the soil, a nutrient deficiency, pesticidal damage, or herbicidal damage.