Investigations in the cause of the phloem necrosis disease of Coffea liberica in Surinam, South America
The presence of the flagellate Phytomonas leptovasorum Stahel in the phloem vessels of Coffea liberica Bull. ex Hiern., suffering from phloem necrosis, was once more demonstrated. The association of the organism with the multiple division of sieve tubes in affected trees was confirmed. The differente nature of a wilting disease caused by the fungus Ceratocystis fimbriata Ellis et Hals. has again been established. No viruses, bacteria, and nematodes could be detected as pathogens of phloem necrosis. Although phloem necrosis in found almost exclusively in mature trees, it was possible to infect young ones by root grafting; the symptoms were, however, less acute here than in older trees. Other species of Coffee can be affected, either by natural infection or by artificial inoculation, but there too, the symptoms - internal as well as external - are less severe than in mature trees of C. liberica. The way of natural infection is still unknown. Hemipteran insects are suspected to transmit the disease, since such insects ara known to be vectors of Phytomonas (= Leptomonas) davidi Lafont in Euphorbia spp. Attemptes to grow the organism in pure culture have failed and hence its pathogenicity could not be established. However, the absence of any evidence towards fungi, viruses, nematodes or bacteria supports the hypothesis that Phytomonas leptovasorum Stahel is the causal agent of the phloem necrosis disease of Coffea liverica in Surinam
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| Format: | biblioteca |
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1968
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| Subjects: | COFFEA LIBERICA, BACTERIOSIS, SINTOMAS DE ENFERMEDADES (PLANTAS), FLOEMA, ANATOMIA DE LA PLANTA, INFECCIONES, SURINAM, AMERICA DEL SUR, HISTOPATOLOGIA, PHYTOMONAS LEPTOVASORUM, |
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