Amaranthus viridis is a weed host of Meloidogyne arenaria in Rio Grande do Sul State, Brazil.
During the summer of 2015, specimens of slender amaranth (Amaranthus viridis) with multiple root galls were detected in a soyabean production field from Novo Barreiro, Rio Grande do Sul, Brazil. Root and soil samples were processed. The causal organism was identified as Meloidogyne arenaria based on morphological, molecular and pathogenicity analyses. This is thought to be the first record of M. arenaria parasitizing A. viridis in Brazil.