Infection of perennial delphiniums by California-aster-yellows virus
AuthorHenry H. P. Severin
Author AffiliationsHenry H. P. Severin was Associate Entomologist in the Experiment Station.
Hilgardia 14(8):411-440. DOI:10.3733/hilg.v14n08p411. June 1942.
Abstract does not appear. First page follows.
Several obscure diseases attack garden varieties of perennial delphiniums (hybrids and horticultural varieties of several species of Delphinium) and cause losses to seed companies, nurserymen, and growers. One of these diseases is particularly troublesome, sometimes causing delphiniums grown from seed to fail totally the second year. Some of the choicest seeds, requiring hand-pollination and bagging, are grown in California; and often these hybrid seeds, also selected for mildew resistance, are lost owing to this disease. Because the symptoms resemble those of California aster yellows on other host plants, an investigation was undertaken to determine whether this disease is caused by the virus of California aster yellows.
In the course of the work on this disease, several other delphinium virus diseases and troubles resembling viroses were investigated. The reports of these investigations have been divided into six papers. The present paper is confined to the work with California aster yellows on perennial delphiniums. Experiments with two other naturally occurring viroses of perennial delphiniums are reported in the other papers of this issue (18), (22).3 The attempts to infect perennial delphiniums experimentally with other viruses are reported in a fourth paper (20). Two leaf variegations of perennial delphiniums resembling viroses but not infectious were encountered; these are reported in a fifth paper (19). Several of the virus diseases attacking perennial delphiniums affect also annual delphiniums, or larkspur (Delphinium Ajacis); the experiments with this host plant are published in a sixth paper (21).
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