Effects of simulated psyllid herbivory on the root development of Japanese knotweed.

Japanese knotweed (Reynoutria japonica) is a notoriously invasive riparian plant species which spreads primarily through detachment and dispersal of rhizomes. Currently management options are limited, there no biological counters to its spread across the country besides one species. Aphalara itadori, psyllid native East Asia has recently been approved by USDA be released in United States control knotweed. This feeds piercing aboveground tissues sucking phloem from stems leaves. We investigated potential role herbivory A. itdori on root system development rhizome mass simulated experiment. hypothesized that would induce plants allocate more resources for defense or regrowth, potentially limiting reducing mass. conducted an experiment with 84 young divided into two treatment groups: herbivory. The was applied weekly, were harvested weekly assess changes via high resolution scanning using WinRhizo software. found does affect system, though results inconsistent between weeks. Simulated decreased length week 5 reduced weeks 3 6. While idiosyncratic, they highlight may negatively impact knotweed, benefits invasion.