Phytophthora palmivora causes root and basal stem rot disease on macaw palm (Acrocomia aculeata) in Brazil

Abstract

Macaw palm (Acrocomia aculeata Jacq.) is an oleaginous palm native to the American continent. It produces oil and has other important characteristics for the industry. In 2022, a severe disease causing basal stem rot, root rot, and plant mortality in a nursery and the field was detected on macaw palm plants in a farm, in João Pinheiro, Minas Gerais state, Brazil. From the rot symptomatic tissue of affected palms, two Phytophthora isolates were obtained by indirect isolation and were grown on PDA. Based on the morphological characteristics, particularly the coenocytic hyphae and papillate sporangia, the isolates were identified as Phytophthora palmivora. For phylogenetic analyses, the internal transcribed spacer (ITS) regions, β-tubulin gene (TUB), translation elongation factor 1-alpha gene (EF1-α), and two mitochondrial genes: cytochrome c oxidase subunit I (COXI) and cytochrome c oxidase subunit II (COXII), were amplified. Phylogenetic analyses confirmed that it is the species P. palmivora. Fulfillment of the Koch's postulates through pathogenicity test confirmed that P. palmivora was the causal agent of root rot and basal stem rot disease in macaw palm. This is the first report of this pathogen causing disease in macaw palms in Brazil.