Abstract
Transmission studies were made by using 29 different species of leafhoppers collected from the sugarcane field where the white leaf disease was very prevalent for the past several years. The resultant data so far revealed the Epitettix hiroglyphicus Matsumura could transmit the disease, but the remainders were incapable of transmitting the disease except for a single case in which 2 plants out of the 58 tested by use of Cicadulina bipunctella were infected. Although further transmission trials must be made, it is inferred that this may be accidental. Therefore, at present E. hiroglyphicus is considered to be the principal vector of our white leaf disease. The incubation period in the vector was about 4-5 weeks so far as the present experiment is concerned, and the same in the host plant was 2.5-3 months when tested during the period from spring to early summer, whereas it was longer, mostly 3-4 months, if the experiment was made in autumn or early winter. Young seedlings appear to be more susceptible than the older, first showing a pale greenish or yellowish stripe(s) on upper young unfolding leaves, then pale yellowish or whitish discoloration on newly unfolding or rolled spindle leaves starting from the base, finally the typical white leaf symptom on the uppermost spindle. These symptoms are occasionally masked, particularly when temperature is relatively low.
