Podridão do caule em pitaias (Hylocereus megalanthus e H. polyrhizus), causadas por Diaporthe no Ceará

Abstract

Brazil stands out among the largest fruit producers in the world, due to its variety and production capacity. Exotic fruits such as pitaya have been gaining prominence in the national and international market and, therefore, their cultivation has been growing in the country, requiring more information about the phytosanitary management of the culture. Knowing the pathogens present in the crop is essential for the adequate control of the disease and thus favoring the maximum productive potential of the plant. This work aims to report as an etiological agent the fungi of the genus Diaporthe causing stem rot in two pitaya species in the state of Ceará, highlighting their symptoms in the laboratory and development between cladodes with shoot development and cladodes with early development of propagation organs. , with a difference of months between the two types of cladodes identified. The material under study was collected from plants with signs of the disease in an orchard of pitayas of the species Hylocereus polyrhizus and H. megalanthus in Experimental Area I of the Federal University of Ceará, Campus of Pici, Fortaleza - CE. The samples were taken to the UFC Mycology Laboratory where three Diaporthe fungi were isolated. The isolates were inoculated by wound in young and old, cultivated in a forest house, of the two pitaya species. In the pathogenicity test, the isolates were inoculated by wound in cladodes with shoot development and cladodes with early propagation organ development, cultivated in a greenhouse, of the two pitaya species. Pathogenicity was confirmed for all isolates obtained in this study. The difference between the cladodes inoculated with shoot development and cladodes with the beginning of propagation organ development don't interfere with the development of the fungus. The isolate UFCM-0709 showed the highest level of virulence in the species H. megalanthus. This is the first report of Diaporthe causing stem rot in H. megalanthus in the world and the first report of the three phytopathogenic isolates in pitaya in the Americas