The period of greatest activity of the psyllid corresponds with the periods of new growth of citrus. Citrus trees in advanced stages of decline are somewhat similar to those affected by tristeza. Field recognition of greening in Asia from symptoms alone is often difficult. Very similar leaf symptoms may be caused by a wide variety of factors varying from nutritional disorders to the presence of other diseases such as root rots and gummosis, tristeza, and exocortis. Capoor et al.
Young leaves are chlorotic, with green banding along the major veins.
Mature leaves have yellowish-green patches between veins, and midribs are yellow. In severe cases, leaves become chlorotic and have scattered spots of green. Fruits on greened trees are small, generally lopsided, underdeveloped, unevenly colored, hard, and poor in juice. The columella was found to be almost always curved in sweet orange fruits and apparently the most reliable diagnostic symptom of greening. Most seeds in diseased fruits are small and dark colored.