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Identidade entre o mosaico comum do algodoeiro e a clorose infecciosa das malváceas

Identity between ordinary cotton mosaic and abutilon mosaic

Identidade entre o mosaico comum do algodoeiro e a clorose infecciosa das malváceas

Identity between ordinary cotton mosaic and abutilon mosaic

A. S. Costa

SUMMARY

Ordinary cotton mosaic has been known to be present in cotton plantings in the state of São Paulo for many years. Since studies on the disease were begun, it was suspected that cotton mosaic could be related to Abutilon mosaic, a disease quite widespread among native species of Sida in São Paulo.

Attempts made in the past to transmit Abutilon mosaic virus from infected Sida plants to cotton plants, by grafting, failed. Also negative results were obtained in attempts to transmit cotton mosaic from cotton to cotton by means of the white fly, Bemisia costalimai Bondar (probably the same white fly as B. tabaci (Genn.).

Other attempts were made more recently to transmit cotton mosaic from cotton to cotton by means of a white fly of the genus Bemisia. These tests gave negative results again. However, ordinary cotton mosaic was induced in cotton plants inoculated by the same species of white fly when the insects were fed on Sida micrantha plants infected with the Abutilon mosaic virus. Mosaic was also induced in various other Malvacex, such as Hibiscus esculentus, Althea rosse, and Sida rhombifolia, when these plants were inoculated with white flies from the same source. Of great interest was the fact that the Abutilon mosaic virus from S. micrantha was transmitted to plants outside Malvacex. Nicandra physaloides was very susceptible to the virus, showing strong mosaic, crinkling and malformation of leaves, and necrosis. The bean plant (Phaseolus vulgaris) was also very susceptible, and when infected showed severe stunting, mosaic, and curling of leaves, which also became very small in size. Pods were not formed by diseased plants in most cases, but occasionally two or three malformed pods were noticed on them. Other legume plants such as guar (Cyamopsis'tetragonalobus) and Cannavalia ensijormis were also affected.

The disease caused by Abutilon mosaic virus in bean plants has been recorded in the field. Its incidence and economic importance have not been determined yet.

Ordinary cotton mosaic is of little economic importance in most plantings. The number of diseased plants very seldom exceeds two or three per cent. In a few situations where incidence of the disease is high, it might be advisable to erradicate native species of Sida from the planting and its vicinities, as an attempt to reduce the incidence of the disease among the cotton plants.

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Recebida para publicação em 10 de julho de 1954.

Datas de Publicação

  • Publicação nesta coleção
    18 Maio 2010
  • Data do Fascículo
    1954
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