Abstract
Aeonium, or tree houseleek (Aeonium arboreum), is a bushy, perennial succulent and a popular ornamental plant in regions such as California, New Zealand, Australia, Sicily, Gibraltar, and Chile. It features rosettes of soft, waxy leaves at the tips of sparsely branched or occasionally single, bare stems. It is drought-tolerant and has a variety of colors and forms, making it a popular ornamental plant. In July 2024, a diseased Aeonium plant was submitted by a home gardener from Los Angeles County, California, to the Department of Nematology at the University of California, Riverside (UCR), for diagnosis. Root galls were observed on the plant, and further examination revealed high numbers of root-knot nematodes (Meloidogyne sp.). Molecular species identification was conducted using ribosomal DNA, mitochondrial haplotyping, and species-specific primer techniques, including the TRNAH/MHR106 and MORF/MTHIS primer sets, along with Meloidogyne incognita-specific primers (MIF/MIR). Amplification and sequencing of the marker genes identified the root-knot nematode infecting Aeonium as M. incognita. To our knowledge, this study presents the first report of M. incognita infecting Aeonium worldwide.