Work done at: Botany Department, University of Gorakhpur, Gorakhpur.
White clover was more suitable source and test plant than potato and Datura stramonium L. for transmission of the potato purple top roll pathogen by Orosius albicinctus Dist. Adaxial surface of leaf was best site for acquisition and transmission by leaf hopper vector. Individual insects were consistent, intermittent and poor transmitters. Female insects survived longer and were also more consistent transmitters than males. Transmission became erratic as the insect aged but most of them retained inoculativity until death. The insects recovered the pathogen, from infected plants, only one day before the appearance of disease symptoms.
Transmission of the potato purple top roll (PTR) pathogen (mycolasmalike organisms) by the leaf hopper vector Orosius albicinctus Dist. was first demonstrated in 1973 (5). Several factor, such as sex and age of insects, length of acquisition, incubation and transmission feeding periods and number of insects per plant were shown to effect transmission (6, 7). This study was conducted to determine the effect of source host and test plant species their parts. Transmission behaviour of insects during their life span and recovory of the pathogen from infected plants after inoculation were also investigated.
