| Abstrakt: |
1. An account is given of a disease of roses known as "Rose Wilt" or Dieback," occurring in Australia. 2. The symptoms of the disease may he summarized as follows : (a) Leaves recurved on petioles, giving a wilted appearance to the plant. (Rose Wilt stage.) (b) The leaves become very brittle and defoliation soon occurs. The twigs and branches rapidly die hack, due to the progress of the disease. (Dieback stage.) 3. In the early stage of the disease (a) bacteria were not seen in sections of the diseased tissues. In the later stage (b) they were, present. 4. The disease has been shown to be due to a filterable organism or particle, thus placing it in the class of virus diseases. Transmission of the disease has been accomplished by inoculation of filtered juice. Experiments to test whether the rose aphis was an insect vector in connection with the disease yielded inconclusive results. Further work on this disease has been interrupted by the writer's departure for England. [ABSTRACT FROM AUTHOR] |
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