Disease symptoms may vary in expression on foliage, stems, roots and fruit, and may not in all cases resemble those illustrated in various publications. Symptoms can vary considerably from mild to severe depending upon infection period, climatic conditions, and age of tissue when infection occurred. When in doubt about disease identification, seek advice before committing to costly and perhaps inappropriate corrective measures. Infection by greasy spot produces a swelling on the lower leaf surface. A yellow mottle appears at the corresponding point on the upper leaf surface.
Infection causes premature leaf drop which occurs mostly in winter and early spring.
Pinpoint black specks occur between the oil glands with infection on grapefruit. The living cells adjacent to the specks often retain a green color for much longer than normal or even when the fruit is degreened by ethylene. Small, pale orange, somewhat circular, elevated spots on leaves and fruit are the first evidence of the disease. The crests of the wart-like growths usually become covered with a corky pale tissue and become somewhat flattened as the fruit matures especially on grapefruit. Badly infected leaves become very crinkled, distorted, and stunted.