General plantation of citronella cv. Java 2 was maintained following recommended agricultural practices at the Experimental Farm of Central Institute of Medicinal and Aromatic Plants, Field Station, Hyderabad, India. The experimental station has a semi-arid tropical climate. The experiment was conducted in the same plantation for 2 consecutive years during the summer month of June 1996 and 1997, when the incidence of the disease was higher. In each year, 12 each of healthy and diseased plants were selected at random and harvested. The occurrence of the disease is generally observed during the hot summer season months, when the temperatures are in the range 36-43 ℃. Initial symptoms of the pest attack appear as yellow specks or blotches, mostly along leaf margins, that in later stages develop into yellow streaks running along the length of the affected leaves. Emerging young leaves are pale green to yellow coloured, twisted, crinkled, developed into whip-like structures and in severe cases of infection fail to open. Even if they do open, these leaves fail to exhibit a smooth leaf surface. Severely affected older leaves turn brown, dry and die. The overall growth and development of the infected plant is severely affected, giving it a dwarfed and unhealthy appearance.

The essential oil examined by GC and GC-MS from cultivated healthy plants contained citronellal (28.4%), geraniol (24.8%), citronellol (11.8%) and elemol (10.2%). The major components from diseased plants were geraniol (19.0-25.5%), elemol (15.3-20.4%), citronellal (13.4-19.1%) and citronellol (12.9-15.1%). Caryophyllene oxide (3.5-6.0%) was an important minor component.