1Central Potato Research Institute, Simla-1, (H.P.).
The agent of witch's broom (WB) disease of potato is transmitted througb tubers, dodder (Cuscuta hyalina) and leafhoppers (Alebroides dravidanus Ram. et Menon and Orosius albicinctus Dist). WB symptoms are masked at very low and high temperatures. Depending on the degree of variability of the WB symptoms in potato and tomato plants various isolates have been grouped. On the basis of the reactions of a large number of distinct symptomatic isolates on a set of solanaceous differentials, viz. potato van. Kufri Jyoti, Kufri Kuber; tree-tomato, brinjal and tomato vars, Bonny Best &, Local Gola, five strains of WB were identified. Tree-tomato, tomato var. Bonny Best and brinjal proved to be good differentials. Complex infections of WB strains in the hosts were observed but diagnostic symptoms of strain complexes were apparent on tomato plants only.
