Abstract
Tulip plants of the variety William Pitt were inoculated at different growing stages with tulip mosaic virus. The inoculum used was pressed leaf sap of naturally infected William Pitt showing typical flower breaking.
(1) Inoculation at post emergence stage: When the plants emerged above the ground, and attained 5-10cm in height, outer two leaves were rubbed with the inoculum added with carborandum. After about 40 days, when flowers bloomed, they were partly dark red and partly white (partial “break”). In the following year, flowers of the plants from these bulbs exclusively showed typical breaking.
(2) Inoculation at flower bud appearance stage; When three leaves were inoculated with the inoculum, all flowers showed dark streaks on the pink petal (self “break”). In the following year, all the flowers of the plants grown from these bulbs showed typical breaking.
(3) When tulip plants were twice inoulated until flower bud appearance stage, all flowers showed typical breaking in the current season.
(4) Inoculation at blooming time: No current season symptoms appeared in the plants inoculated at this stage. All the flowers of plants grown from these bulbs, however, showed typical breaking in the following season.
(5) Inoulation at blasting stage: About 20 days after the blooming time, partly blasted leaves were inoculated. In the following season, flower breaking of various types above stated appeared in plants grown from produced on each inoculated plant.
(6) It has been established that inoculation of pink tulip plants (vrieties William Pitt and Clara Butt) in an early developmental stage is most useful for detecting virus.
(7) It has also been established that color changes that take place in tulip flowers are mostly determined by the age of the plant when infected.
