Studies on Aster Yellows

Abstract

An infectious chlorosis known as " aster yellows," because it attacks the China aster, Callistephus chinensis Nees, is prevalent throughout the United States. The aster is grown extensively in other parts of the world, especially in Europe and the Orient, but the disease is known to be prevalent only in North America. Although it has been present here for many years and is a serious hindrance to aster growing, it has been given little attention by plant pathologists. This is partly, no doubt, because it belongs to that group of obscure plant maladies known as virus diseases. Another probable reason why pathologists have neglected aster yellows is that it is not known to attack any plant of great economic importance. Smith (26) gave a good description of the disease in 1902 and suggested that it might go to other plants in the Compositae closely related to the China aster. He was unable to find any parasitic organism associated with yellows and suspected its relationship to the virus disease group. Whether the incidence of aster yellows has changed during the past twenty-five years is not known. Smith speaks of it as "widespread and destructive." At the present time it is so serious in many sections of the country that the planting of asters is being greatly restricted or even abandoned. Aster plots showing 90 to 95 percent of yellowed plants are not uncommon throughout the eastern United States. One hundred percent infection has occasionally been observed in fields containing several hundred plants. In certain localities, however, the disease is not yet serious, and small plantings sometimes remain disease-free to the end of the season.At the suggestion of Doctor William Crocker, the writer undertook a study of aster yellows in the spring of 1923. The work, started at that time, has been continued during the past three years. Special attention was given to the means by which the disease is transmitted to healthy plants, to its relationship to similar well known diseases of other plants, to its overwintering in wild host plants, to the life and habits of its insect carrier, to its incubation period in both plant and insect host, to its host range, to possible methods for its control, and to its etiology. Several brief reports covering certain phases of the work have already been published (12,14, IS). The object of the present paper is to record in more detail observa-

‘Candidatus Phytoplasma asteris’, a novel phytoplasma taxon associated with aster yellows and related diseases

“…The 'Candidatus P. asteris' concept encompasses all known subgroups within group 16SrI. Strains that belong to subgroups 16SrI-A, 16SrI-B and 16SrI-C are distributed worldwide, are associated with more than 80 plant species and can be transmitted by more than 30 species of insect vectors (Kunkel, 1926;Brcák, 1979;Tsai, 1979). Subgroup 16SrI-B represents the largest and most diverse strain cluster in the group.…”

“…Aster yellows, which attacks the China aster, Callistephus chinensis Nees, was widespread throughout the eastern United States at the turn of the 20th century (Kunkel, 1926). It was transmitted primarily by the aster leafhopper Macrosteles quadrilineatus Forbes (formerly Macrosteles fascifrons Stal.)…”

Effectiveness of Antibiotics Applied as Postinoculation Sprays Against Clover Phyllody and Aster Yellows

“…Plant Sci, (Jan. 1973) ir.rvestigated by other workers in the search for a causal agent control. Effects of several antibiotics on aster yellows and clover phyllody diseases have been reported (Davis et al 1968;Freitag and Smith 1969;Davis and Whitcomb 1970;Chiykowski 1972;Sinha and Peterson 1972 Kunkel (1926) For personal use only. LITERATURE CITED…”

Polymerase Chain Reaction for Phytoplasmas Detection

“…1). Phytoplasma-type diseases of plants for long time were believed to be caused by viruses considering their infective spreading, symptomatology, and transmission by insects (84,85,86,119,90). Etiology of these pathogens was explored accidentally by group of Japanese sciences (45).…”