Etiology of Severe Mosaic and Its Effect on Safflower. J. M. Klisiewicz, Research Plant Pathologist, USDA, ARS, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 67:112-114. Accepted for publication 14 September 1982. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1983. DOI: 10.1094/PD-67-112.

Severe mosaic, leaf distortion, and stunted growth were characteristic symptoms caused by turnip mosaic virus (TuMV) in safflower growing in the Sacramento Valley of California. Symptoms were reproduced in safflower plants inoculated with juice extracted from diseased plants. Rotting of seed ovules resulted in severe reduction of seed yield in TuMV-infected plants. Some cultivars developed similar necrotic local lesions and systemic necrosis reactions to both TuMV and lettuce mosaic virus. Spread of the virus from weed hosts to safflower by aphids in nature was indicated by transmission of TuMV from the commonly occurring weeds Brassica geniculata and B. campestris to safflower by Myzus persicae. The virus was identified on the basis of host range, physical and morphological properties, and serology.