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Black crust on rubber tree: causal agent, environmental influence on pre-penetration in different rubber tree clones, selection of resistant clones and biological control in susceptible clones

Abstract

The rubber tree (Hevea brasiliensis Müell. Arg.) Is a species from the Amazon region, widely cultivated in Brazil. Over the past few years, with climate changes added to factors such as the expansion of rubber plantations to different locations with different environmental conditions, the occurrence of a disease that has always been treated as secondary, the black crust, has become a concern due to the early fall of rubber tree leaves This disease has been associated with the fungi Phyllachora huberi and Rosenscheldiella heveae, which can occur in isolation together. Because this disease has been treated as of low importance in rubber trees, studies related to it are scarce. Thus, updated information to determine which species of Phyllachora and Rosenscheldiella occur and which are prevalent in the main rubber-producing regions and which characterize the populations of the pathogen are important for the country. Thus, this work aims to identify and characterize species of associated fungi associated with the black rubber crust in different Brazilian states. For that, phylogenetic analyzes will be performed, using partial sequences of the partial rDNA subunit (28S, LSU), ribosomal rDNA region (18S, SSU) and the ITS-5.8S rDNA region of the collected isolates. The isolates will also be characterized pathogenically through inoculation in different clones of rubber trees. Allied to the clone differential reaction experiment, disease control tests will be carried out with commercially available biological agents and isolated from the microfauna of rubber tree leaves. Finally, isolates representative of the main species found will be evaluated for the percentage of conidia germinated during the pre-penetration phase and their penetration in rubber tree leaflets, under the influence of different temperatures and wetting periods. The results obtained will allow a better understanding of the etiological and epidemiological aspects of the disease, providing subsidies for the development and the adoption of adequate control methods for this rubber tree in Brazil. (AU)

Articles published in Agência FAPESP Newsletter about the research grant: